diff --git a/internal/checker/pseudotypenodebuilder.go b/internal/checker/pseudotypenodebuilder.go
index cf8046803f9..c4b3acedd03 100644
--- a/internal/checker/pseudotypenodebuilder.go
+++ b/internal/checker/pseudotypenodebuilder.go
@@ -174,6 +174,8 @@ func (b *NodeBuilderImpl) pseudoTypeToNode(t *pseudochecker.PseudoType) *ast.Nod
 		return b.f.NewLiteralTypeNode(b.f.NewKeywordExpression(ast.KindFalseKeyword))
 	case pseudochecker.PseudoTypeKindTrue:
 		return b.f.NewLiteralTypeNode(b.f.NewKeywordExpression(ast.KindTrueKeyword))
+	case pseudochecker.PseudoTypeKindVoid:
+		return b.f.NewKeywordTypeNode(ast.KindVoidKeyword)
 	case pseudochecker.PseudoTypeKindSingleCallSignature:
 		d := t.AsPseudoTypeSingleCallSignature()
 		signature := b.ch.getSignatureFromDeclaration(d.Signature)
@@ -753,6 +755,8 @@ func (b *NodeBuilderImpl) pseudoTypeToType(t *pseudochecker.PseudoType) *Type {
 		return b.ch.falseType
 	case pseudochecker.PseudoTypeKindTrue:
 		return b.ch.trueType
+	case pseudochecker.PseudoTypeKindVoid:
+		return b.ch.voidType
 	case pseudochecker.PseudoTypeKindStringLiteral, pseudochecker.PseudoTypeKindNumericLiteral, pseudochecker.PseudoTypeKindBigIntLiteral:
 		source := t.AsPseudoTypeLiteral().Node
 		return b.ch.getRegularTypeOfExpression(source) // big shortcut, uses cached expression types where possible
diff --git a/internal/fourslash/_scripts/failingTests.txt b/internal/fourslash/_scripts/failingTests.txt
index a4292fe50f3..f9f643f6e91 100644
--- a/internal/fourslash/_scripts/failingTests.txt
+++ b/internal/fourslash/_scripts/failingTests.txt
@@ -61,9 +61,12 @@ TestCodeFixInferFromUsageRestParam2
 TestCodeFixInferFromUsageRestParam3
 TestCodeFixInferFromUsageVariable3JS
 TestCodeFixMissingTypeAnnotationOnExports16
+TestCodeFixMissingTypeAnnotationOnExports22_formatting
 TestCodeFixMissingTypeAnnotationOnExports23_heritage_formatting
 TestCodeFixMissingTypeAnnotationOnExports25_heritage_formatting_3
 TestCodeFixMissingTypeAnnotationOnExports28_long_types
+TestCodeFixMissingTypeAnnotationOnExports33_methods
+TestCodeFixMissingTypeAnnotationOnExports43_expando_functions_2
 TestCodeFixSpelling4
 TestCodeFixSpelling5
 TestCodeFixSpellingCaseSensitive1
diff --git a/internal/fourslash/tests/manual/codeFixMissingTypeAnnotationOnExports46-decorators-experimental_test.go b/internal/fourslash/tests/manual/codeFixMissingTypeAnnotationOnExports46-decorators-experimental_test.go
index 59e717e5ee4..f1c136ff932 100644
--- a/internal/fourslash/tests/manual/codeFixMissingTypeAnnotationOnExports46-decorators-experimental_test.go
+++ b/internal/fourslash/tests/manual/codeFixMissingTypeAnnotationOnExports46-decorators-experimental_test.go
@@ -61,7 +61,7 @@ export class A {
   getSelf(): this {
     return this;
   }
-  passParameter(@parameterDecorator() param: number = foo()): void {}
+  passParameter(@parameterDecorator() param: number = foo()) {}
   @getterDecorator()
   get a(): number {
     return foo();
diff --git a/internal/pseudochecker/lookup.go b/internal/pseudochecker/lookup.go
index 015f88f313a..b658fa12c67 100644
--- a/internal/pseudochecker/lookup.go
+++ b/internal/pseudochecker/lookup.go
@@ -223,6 +223,9 @@ func (ch *PseudoChecker) typeFromSingleReturnExpression(fn *ast.Node) *PseudoTyp
 
 		body := fn.Body()
 		if ast.IsBlock(body) {
+			if len(body.Statements()) == 0 {
+				return PseudoTypeVoid
+			}
 			ast.ForEachReturnStatement(body, func(stmt *ast.Node) bool {
 				if stmt.Parent != body { // Why bail on nested return statements?
 					candidateExpr = nil
diff --git a/internal/pseudochecker/type.go b/internal/pseudochecker/type.go
index 6966ed811e1..425bd365c7b 100644
--- a/internal/pseudochecker/type.go
+++ b/internal/pseudochecker/type.go
@@ -33,6 +33,7 @@ const (
 	PseudoTypeKindBoolean
 	PseudoTypeKindFalse
 	PseudoTypeKindTrue
+	PseudoTypeKindVoid
 	PseudoTypeKindSingleCallSignature
 	PseudoTypeKindTuple
 	PseudoTypeKindObjectLiteral
@@ -77,6 +78,7 @@ var (
 	PseudoTypeBoolean   = newPseudoType(PseudoTypeKindBoolean, &PseudoTypeBase{})
 	PseudoTypeFalse     = newPseudoType(PseudoTypeKindFalse, &PseudoTypeBase{})
 	PseudoTypeTrue      = newPseudoType(PseudoTypeKindTrue, &PseudoTypeBase{})
+	PseudoTypeVoid      = newPseudoType(PseudoTypeKindVoid, &PseudoTypeBase{})
 )
 
 // PseudoTypeDirect directly encodes the type referred to by a given TypeNode
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt
index 2bc5caf198c..8671d84aa7c 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt
@@ -1,10 +1,9 @@
 isolatedDeclarationErrors.ts(2,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 isolatedDeclarationErrors.ts(5,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
-isolatedDeclarationErrors.ts(7,30): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrors.ts(8,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 
 
-==== isolatedDeclarationErrors.ts (4 errors) ====
+==== isolatedDeclarationErrors.ts (3 errors) ====
     function errorOnAssignmentBelowDecl(): void {}
     errorOnAssignmentBelowDecl.a = "";
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -16,10 +15,6 @@ isolatedDeclarationErrors.ts(8,1): error TS9023: Assigning properties to functio
 !!! error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
     
     const errorOnMissingReturn = () => {}
-                                 ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9027 isolatedDeclarationErrors.ts:7:7: Add a type annotation to the variable errorOnMissingReturn.
-!!! related TS9030 isolatedDeclarationErrors.ts:7:30: Add a return type to the function expression.
     errorOnMissingReturn.a = "";
     ~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt.diff
new file mode 100644
index 00000000000..2d6c3665ab2
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrors.errors.txt.diff
@@ -0,0 +1,25 @@
+--- old.isolatedDeclarationErrors.errors.txt
++++ new.isolatedDeclarationErrors.errors.txt
+@@= skipped -0, +0 lines =@@
+ isolatedDeclarationErrors.ts(2,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+ isolatedDeclarationErrors.ts(5,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+-isolatedDeclarationErrors.ts(7,30): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrors.ts(8,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+
+
+-==== isolatedDeclarationErrors.ts (4 errors) ====
++==== isolatedDeclarationErrors.ts (3 errors) ====
+     function errorOnAssignmentBelowDecl(): void {}
+     errorOnAssignmentBelowDecl.a = "";
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+@@= skipped -15, +14 lines =@@
+ !!! error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+     
+     const errorOnMissingReturn = () => {}
+-                                 ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9027 isolatedDeclarationErrors.ts:7:7: Add a type annotation to the variable errorOnMissingReturn.
+-!!! related TS9030 isolatedDeclarationErrors.ts:7:30: Add a return type to the function expression.
+     errorOnMissingReturn.a = "";
+     ~~~~~~~~~~~~~~~~~~~~~~
+ !!! error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt
index 7e9b2904f7a..416a41adb20 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt
@@ -1,5 +1,4 @@
 isolatedDeclarationErrorsClasses.ts(3,5): error TS9012: Property must have an explicit type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsClasses.ts(4,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(8,18): error TS7006: Parameter 'p' implicitly has an 'any' type.
 isolatedDeclarationErrorsClasses.ts(8,18): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(9,23): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
@@ -11,7 +10,6 @@ isolatedDeclarationErrorsClasses.ts(36,5): error TS9038: Computed property names
 isolatedDeclarationErrorsClasses.ts(36,6): error TS2304: Cannot find name 'missing'.
 isolatedDeclarationErrorsClasses.ts(38,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(40,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
-isolatedDeclarationErrorsClasses.ts(42,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(42,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(44,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
 isolatedDeclarationErrorsClasses.ts(44,35): error TS7006: Parameter 'v' implicitly has an 'any' type.
@@ -26,7 +24,7 @@ isolatedDeclarationErrorsClasses.ts(56,5): error TS7010: '[noAnnotationLiteralNa
 isolatedDeclarationErrorsClasses.ts(56,5): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
 
 
-==== isolatedDeclarationErrorsClasses.ts (26 errors) ====
+==== isolatedDeclarationErrorsClasses.ts (24 errors) ====
     export class Cls {
     
         field = 1 + 1;
@@ -34,9 +32,6 @@ isolatedDeclarationErrorsClasses.ts(56,5): error TS9013: Expression type can't b
 !!! error TS9012: Property must have an explicit type annotation with --isolatedDeclarations.
 !!! related TS9029 isolatedDeclarationErrorsClasses.ts:3:5: Add a type annotation to the property field.
         method() {}
-        ~~~~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9034 isolatedDeclarationErrorsClasses.ts:4:5: Add a return type to the method
     
         methodOk(): void {}
     
@@ -102,9 +97,6 @@ isolatedDeclarationErrorsClasses.ts(56,5): error TS9013: Expression type can't b
     
         [noAnnotationStringName]() { }
         ~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9034 isolatedDeclarationErrorsClasses.ts:42:5: Add a return type to the method
-        ~~~~~~~~~~~~~~~~~~~~~~~~
 !!! error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
     
         [noParamAnnotationStringName](v): void { }
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt.diff
new file mode 100644
index 00000000000..25abdeeb2d1
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsClasses.errors.txt.diff
@@ -0,0 +1,45 @@
+--- old.isolatedDeclarationErrorsClasses.errors.txt
++++ new.isolatedDeclarationErrorsClasses.errors.txt
+@@= skipped -0, +0 lines =@@
+ isolatedDeclarationErrorsClasses.ts(3,5): error TS9012: Property must have an explicit type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsClasses.ts(4,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(8,18): error TS7006: Parameter 'p' implicitly has an 'any' type.
+ isolatedDeclarationErrorsClasses.ts(8,18): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(9,23): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
+@@= skipped -10, +9 lines =@@
+ isolatedDeclarationErrorsClasses.ts(36,6): error TS2304: Cannot find name 'missing'.
+ isolatedDeclarationErrorsClasses.ts(38,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(40,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+-isolatedDeclarationErrorsClasses.ts(42,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(42,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(44,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+ isolatedDeclarationErrorsClasses.ts(44,35): error TS7006: Parameter 'v' implicitly has an 'any' type.
+@@= skipped -15, +14 lines =@@
+ isolatedDeclarationErrorsClasses.ts(56,5): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+
+
+-==== isolatedDeclarationErrorsClasses.ts (26 errors) ====
++==== isolatedDeclarationErrorsClasses.ts (24 errors) ====
+     export class Cls {
+     
+         field = 1 + 1;
+@@= skipped -8, +8 lines =@@
+ !!! error TS9012: Property must have an explicit type annotation with --isolatedDeclarations.
+ !!! related TS9029 isolatedDeclarationErrorsClasses.ts:3:5: Add a type annotation to the property field.
+         method() {}
+-        ~~~~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9034 isolatedDeclarationErrorsClasses.ts:4:5: Add a return type to the method
+     
+         methodOk(): void {}
+     
+@@= skipped -67, +64 lines =@@
+ !!! error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+     
+         [noAnnotationStringName]() { }
+-        ~~~~~~~~~~~~~~~~~~~~~~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9034 isolatedDeclarationErrorsClasses.ts:42:5: Add a return type to the method
+         ~~~~~~~~~~~~~~~~~~~~~~~~
+ !!! error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+     
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt
index adc2ffbf0df..6ab24b85860 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt
@@ -1,4 +1,3 @@
-isolatedDeclarationErrorsExpandoFunctions.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsExpandoFunctions.ts(3,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 isolatedDeclarationErrorsExpandoFunctions.ts(4,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 isolatedDeclarationErrorsExpandoFunctions.ts(5,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
@@ -7,11 +6,8 @@ isolatedDeclarationErrorsExpandoFunctions.ts(7,1): error TS9023: Assigning prope
 isolatedDeclarationErrorsExpandoFunctions.ts(8,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 
 
-==== isolatedDeclarationErrorsExpandoFunctions.ts (7 errors) ====
+==== isolatedDeclarationErrorsExpandoFunctions.ts (6 errors) ====
     export function foo() {}
-                    ~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9031 isolatedDeclarationErrorsExpandoFunctions.ts:1:17: Add a return type to the function declaration.
     
     foo.apply = () => {}
     ~~~~~~~~~
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt.diff
new file mode 100644
index 00000000000..b9b639745e8
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsExpandoFunctions.errors.txt.diff
@@ -0,0 +1,20 @@
+--- old.isolatedDeclarationErrorsExpandoFunctions.errors.txt
++++ new.isolatedDeclarationErrorsExpandoFunctions.errors.txt
+@@= skipped -0, +0 lines =@@
+-isolatedDeclarationErrorsExpandoFunctions.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsExpandoFunctions.ts(3,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+ isolatedDeclarationErrorsExpandoFunctions.ts(4,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+ isolatedDeclarationErrorsExpandoFunctions.ts(5,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+@@= skipped -6, +5 lines =@@
+ isolatedDeclarationErrorsExpandoFunctions.ts(8,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+
+
+-==== isolatedDeclarationErrorsExpandoFunctions.ts (7 errors) ====
++==== isolatedDeclarationErrorsExpandoFunctions.ts (6 errors) ====
+     export function foo() {}
+-                    ~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9031 isolatedDeclarationErrorsExpandoFunctions.ts:1:17: Add a return type to the function declaration.
+     
+     foo.apply = () => {}
+     ~~~~~~~~~
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt
index cbec933ded0..3d3b066c1a8 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt
@@ -1,4 +1,3 @@
-isolatedDeclarationErrorsFunctionDeclarations.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsFunctionDeclarations.ts(3,35): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsFunctionDeclarations.ts(7,49): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsFunctionDeclarations.ts(7,66): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
@@ -6,11 +5,8 @@ isolatedDeclarationErrorsFunctionDeclarations.ts(7,81): error TS9013: Expression
 isolatedDeclarationErrorsFunctionDeclarations.ts(9,55): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
 
 
-==== isolatedDeclarationErrorsFunctionDeclarations.ts (6 errors) ====
+==== isolatedDeclarationErrorsFunctionDeclarations.ts (5 errors) ====
     export function noReturn() {}
-                    ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9031 isolatedDeclarationErrorsFunctionDeclarations.ts:1:17: Add a return type to the function declaration.
     
     export function noParamAnnotation(p): void {}
                                       ~
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt.diff
new file mode 100644
index 00000000000..e7431ea0d33
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsFunctionDeclarations.errors.txt.diff
@@ -0,0 +1,20 @@
+--- old.isolatedDeclarationErrorsFunctionDeclarations.errors.txt
++++ new.isolatedDeclarationErrorsFunctionDeclarations.errors.txt
+@@= skipped -0, +0 lines =@@
+-isolatedDeclarationErrorsFunctionDeclarations.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsFunctionDeclarations.ts(3,35): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsFunctionDeclarations.ts(7,49): error TS9011: Parameter must have an explicit type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsFunctionDeclarations.ts(7,66): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+@@= skipped -5, +4 lines =@@
+ isolatedDeclarationErrorsFunctionDeclarations.ts(9,55): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+
+
+-==== isolatedDeclarationErrorsFunctionDeclarations.ts (6 errors) ====
++==== isolatedDeclarationErrorsFunctionDeclarations.ts (5 errors) ====
+     export function noReturn() {}
+-                    ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9031 isolatedDeclarationErrorsFunctionDeclarations.ts:1:17: Add a return type to the function declaration.
+     
+     export function noParamAnnotation(p): void {}
+                                       ~
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt
index 8fa23907bd2..3bf5c1d3d94 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt
@@ -1,11 +1,7 @@
 isolatedDeclarationErrorsObjects.ts(7,8): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
 isolatedDeclarationErrorsObjects.ts(12,12): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
 isolatedDeclarationErrorsObjects.ts(16,12): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
-isolatedDeclarationErrorsObjects.ts(21,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsObjects.ts(24,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsObjects.ts(25,8): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
-isolatedDeclarationErrorsObjects.ts(29,9): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsObjects.ts(32,9): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationErrorsObjects.ts(40,9): error TS7032: Property 'singleSetterBad' implicitly has type 'any', because its set accessor lacks a parameter type annotation.
 isolatedDeclarationErrorsObjects.ts(40,25): error TS7006: Parameter 'value' implicitly has an 'any' type.
 isolatedDeclarationErrorsObjects.ts(40,25): error TS9009: At least one accessor must have an explicit type annotation with --isolatedDeclarations.
@@ -19,7 +15,7 @@ isolatedDeclarationErrorsObjects.ts(77,5): error TS9016: Objects that contain sh
 isolatedDeclarationErrorsObjects.ts(84,9): error TS9015: Objects that contain spread assignments can't be inferred with --isolatedDeclarations.
 
 
-==== isolatedDeclarationErrorsObjects.ts (19 errors) ====
+==== isolatedDeclarationErrorsObjects.ts (15 errors) ====
     export let o = {
         a: 1,
         b: ""
@@ -53,17 +49,9 @@ isolatedDeclarationErrorsObjects.ts(84,9): error TS9015: Objects that contain sp
     
     export let oWithMethods = {
         method() { },
-        ~~~~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:20:12: Add a type annotation to the variable oWithMethods.
-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:21:5: Add a return type to the method
         okMethod(): void { },
         a: 1,
         bad() { },
-        ~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:20:12: Add a type annotation to the variable oWithMethods.
-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:24:5: Add a return type to the method
         e: V,
            ~
 !!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
@@ -73,17 +61,9 @@ isolatedDeclarationErrorsObjects.ts(84,9): error TS9015: Objects that contain sp
     export let oWithMethodsNested = {
         foo: {
             method() { },
-            ~~~~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:27:12: Add a type annotation to the variable oWithMethodsNested.
-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:29:9: Add a return type to the method
             a: 1,
             okMethod(): void { },
             bad() { }
-            ~~~
-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:27:12: Add a type annotation to the variable oWithMethodsNested.
-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:32:9: Add a return type to the method
         }
     }
     
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt.diff
new file mode 100644
index 00000000000..fb07d7d2353
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsObjects.errors.txt.diff
@@ -0,0 +1,59 @@
+--- old.isolatedDeclarationErrorsObjects.errors.txt
++++ new.isolatedDeclarationErrorsObjects.errors.txt
+@@= skipped -0, +0 lines =@@
+ isolatedDeclarationErrorsObjects.ts(7,8): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+ isolatedDeclarationErrorsObjects.ts(12,12): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+ isolatedDeclarationErrorsObjects.ts(16,12): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+-isolatedDeclarationErrorsObjects.ts(21,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsObjects.ts(24,5): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsObjects.ts(25,8): error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+-isolatedDeclarationErrorsObjects.ts(29,9): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsObjects.ts(32,9): error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationErrorsObjects.ts(40,9): error TS7032: Property 'singleSetterBad' implicitly has type 'any', because its set accessor lacks a parameter type annotation.
+ isolatedDeclarationErrorsObjects.ts(40,25): error TS7006: Parameter 'value' implicitly has an 'any' type.
+ isolatedDeclarationErrorsObjects.ts(40,25): error TS9009: At least one accessor must have an explicit type annotation with --isolatedDeclarations.
+@@= skipped -18, +14 lines =@@
+ isolatedDeclarationErrorsObjects.ts(84,9): error TS9015: Objects that contain spread assignments can't be inferred with --isolatedDeclarations.
+
+
+-==== isolatedDeclarationErrorsObjects.ts (19 errors) ====
++==== isolatedDeclarationErrorsObjects.ts (15 errors) ====
+     export let o = {
+         a: 1,
+         b: ""
+@@= skipped -34, +34 lines =@@
+     
+     export let oWithMethods = {
+         method() { },
+-        ~~~~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:20:12: Add a type annotation to the variable oWithMethods.
+-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:21:5: Add a return type to the method
+         okMethod(): void { },
+         a: 1,
+         bad() { },
+-        ~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:20:12: Add a type annotation to the variable oWithMethods.
+-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:24:5: Add a return type to the method
+         e: V,
+            ~
+ !!! error TS9013: Expression type can't be inferred with --isolatedDeclarations.
+@@= skipped -20, +12 lines =@@
+     export let oWithMethodsNested = {
+         foo: {
+             method() { },
+-            ~~~~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:27:12: Add a type annotation to the variable oWithMethodsNested.
+-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:29:9: Add a return type to the method
+             a: 1,
+             okMethod(): void { },
+             bad() { }
+-            ~~~
+-!!! error TS9008: Method must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9027 isolatedDeclarationErrorsObjects.ts:27:12: Add a type annotation to the variable oWithMethodsNested.
+-!!! related TS9034 isolatedDeclarationErrorsObjects.ts:32:9: Add a return type to the method
+         }
+     }
+     
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt
deleted file mode 100644
index 4981a650dbc..00000000000
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt
+++ /dev/null
@@ -1,361 +0,0 @@
-isolatedDeclarationErrorsReturnTypes.ts(13,45): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(16,41): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(19,41): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(109,65): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(112,61): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(115,61): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(119,83): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(120,66): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(122,79): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(123,62): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(125,79): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(126,62): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(138,73): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(141,69): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(144,69): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(151,38): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(152,21): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(153,57): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(154,40): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(156,51): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(157,34): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(158,70): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(159,53): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(162,53): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(163,36): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(164,72): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(165,55): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(167,66): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(168,49): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(169,85): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-isolatedDeclarationErrorsReturnTypes.ts(170,68): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-
-
-==== isolatedDeclarationErrorsReturnTypes.ts (31 errors) ====
-    // Function Variables
-    export const fnExpressionConstVariable = function foo() { return 0;}
-    export const fnArrowConstVariable = () => "S";
-    
-    export let fnExpressionLetVariable = function foo() { return 0;}
-    export let fnArrowLetVariable = () => "S";
-    
-    export var fnExpressionVarVariable = function foo() { return 0;}
-    export var fnArrowVarVariable = () => "S";
-    
-    // No Errors
-    export const fnExpressionConstVariableOk = function foo(): number { return 0;}
-    export const fnArrowConstVariableOk = (cb = function(){ }): string => "S";
-                                                ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:13:40: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:13:45: Add a return type to the function expression.
-    
-    export let fnExpressionLetVariableOk = function foo(): number { return 0;}
-    export let fnArrowLetVariableOk = (cb = function(){ }): string => "S";
-                                            ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:16:36: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:16:41: Add a return type to the function expression.
-    
-    export var fnExpressionVarVariableOk = function foo(): number { return 0;}
-    export var fnArrowVarVariableOk = (cb = function(){ }): string => "S";
-                                            ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:19:36: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:19:41: Add a return type to the function expression.
-    
-    // Not exported
-    const fnExpressionConstVariableInternal = function foo() { return 0;}
-    const fnArrowConstVariableInternal = () => "S";
-    
-    let fnExpressionLetVariableInternal = function foo() { return 0;}
-    let fnArrowLetVariableInternal = () => "S";
-    
-    var fnExpressionVarVariableInternal = function foo() { return 0;}
-    var fnArrowVarVariableInternal = () => "S";
-    
-    // Function Fields
-    export class ExportedClass { 
-        // Should Error
-        fnExpression = function foo() { return 0; }
-        fnArrow = () => "S";    
-        protected fnExpressionProtected = function foo() { return 0; }
-        protected fnArrowProtected = () => "S";
-    
-        static fnStaticExpression = function foo() { return 0; }
-        static fnStaticArrow = () => "S";
-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
-        protected static fnStaticArrowProtected = () => "S";
-    
-        // Have annotation, so ok 
-        fnExpressionOk = function foo(): number { return 0; }
-        fnArrowOK = (): string => "S";
-        protected fnExpressionProtectedOk = function foo(): number { return 0; }
-        protected fnArrowProtectedOK = (): string => "S";
-    
-        static fnStaticExpressionOk = function foo(): number { return 0; }
-        static fnStaticArrowOk = (): string => "S";
-        protected static fnStaticExpressionProtectedOk = function foo(): number { return 0; }    
-        protected static fnStaticArrowProtectedOk = (): string => "S";
-        
-    
-        // No Error not in declarations
-        private fnExpressionPrivate = function foo() { return 0; }
-        private fnArrowPrivate = () => "S";
-        #fnArrow = () => "S";
-        #fnExpression = function foo() { return 0;}
-        private static fnStaticExpressionPrivate = function foo() { return 0; }
-        private static fnStaticArrowPrivate = () => "S";
-    }
-    
-    // Should error
-    class IndirectlyExportedClass { 
-        fnExpression = function foo() { return 0; }
-        fnArrow = () => "S";
-    
-        static fnStaticExpression = function foo() { return 0; }
-        static fnStaticArrow = () => "S";
-        
-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
-        protected static fnStaticArrowProtected = () => "S";
-    
-        private fnExpressionPrivate = function foo() { return 0; }
-        private fnArrowPrivate = () => "S";
-        #fnArrow = () => "S";
-        #fnExpression = function foo() { return 0;}
-        private static fnStaticExpressionPrivate = function foo() { return 0; }
-        private static fnStaticArrowPrivate = () => "S";
-    }
-    export const instance: IndirectlyExportedClass = new IndirectlyExportedClass();
-    
-    // No Errors
-    class InternalClass { 
-        fnExpression = function foo() { return 0; }
-        fnArrow = () => "S";
-    
-        static fnStaticExpression = function foo() { return 0; }
-        static fnStaticArrow = () => "S";
-        
-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
-        protected static fnStaticArrowProtected = () => "S";
-    
-        private fnExpressionPrivate = function foo() { return 0; }
-        private fnArrowPrivate = () => "S";
-        #fnArrow = () => "S";
-        #fnExpression = function foo() { return 0;}
-        private static fnStaticExpressionPrivate = function foo() { return 0; }
-        private static fnStaticArrowPrivate = () => "S";
-    }
-    const internalInstance: InternalClass = new InternalClass();
-    
-    
-    // Function parameters
-    
-    // In Function Variables - No annotations
-    export const fnParamExpressionConstVariable = function foo(cb = function(){ }) { return 0;}
-                                                                    ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:109:60: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:109:65: Add a return type to the function expression.
-    export const fnParamArrowConstVariable = (cb = () => 1) => "S";
-    
-    export let fnParamExpressionLetVariable = function foo(cb = function(){ }) { return 0;}
-                                                                ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:112:56: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:112:61: Add a return type to the function expression.
-    export let fnParamArrowLetVariable = (cb = () => 1) => "S";
-    
-    export var fnParamExpressionVarVariable = function foo(cb = function(){ }) { return 0;}
-                                                                ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:115:56: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:115:61: Add a return type to the function expression.
-    export var fnParamArrowVarVariable = (cb = () => 1) => "S";
-    
-    // In Function Variables - No annotations on parameter
-    export const fnParamExpressionConstVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
-                                                                                      ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:119:78: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:119:83: Add a return type to the function expression.
-    export const fnParamArrowConstVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
-                                                                     ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:120:61: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:120:66: Add a return type to the function expression.
-    
-    export let fnParamExpressionLetVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
-                                                                                  ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:122:74: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:122:79: Add a return type to the function expression.
-    export let fnParamArrowLetVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
-                                                                 ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:123:57: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:123:62: Add a return type to the function expression.
-    
-    export var fnParamExpressionVarVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
-                                                                                  ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:125:74: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:125:79: Add a return type to the function expression.
-    export var fnParamArrowVarVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
-                                                                 ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:126:57: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:126:62: Add a return type to the function expression.
-    
-    // No Errors
-    export const fnParamExpressionConstVariableOk = function foo(cb = function(): void{ }): number { return 0;}
-    export const fnParamArrowConstVariableOk = (cb = function(): void{ }): string => "S";
-    
-    export let fnParamExpressionLetVariableOk = function foo(cb = function(): void{ }): number { return 0;}
-    export let fnParamArrowLetVariableOk = (cb = function(): void{ }): string => "S";
-    
-    export var fnParamExpressionVarVariableOk = function foo(cb = function(): void{ }): number { return 0;}
-    export var fnParamArrowVarVariableOk = (cb = function(): void{ }): string => "S";
-    
-    export const fnParamExpressionConstVariableInternal = function foo(cb = function(){ }) { return 0;}
-                                                                            ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:138:68: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:138:73: Add a return type to the function expression.
-    export const fnParamArrowConstVariableInternal = (cb = () => 1) => "S";
-    
-    export let fnParamExpressionLetVariableInternal = function foo(cb = function(){ }) { return 0;}
-                                                                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:141:64: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:141:69: Add a return type to the function expression.
-    export let fnParamArrowLetVariableInternal = (cb = () => 1) => "S";
-    
-    export var fnParamExpressionVarVariableInternal = function foo(cb = function(){ }) { return 0;}
-                                                                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:144:64: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:144:69: Add a return type to the function expression.
-    export var fnParamArrowVarVariableInternal = (cb = () => 1) => "S";
-    
-    
-    // In Function Fields
-    export class FnParamsExportedClass { 
-        // Should Error
-        fnExpression = function foo(cb = function(){ }) { return 0; }
-                                         ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:151:33: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:151:38: Add a return type to the function expression.
-        fnArrow = (cb = function(){ }) => "S";
-                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:152:16: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:152:21: Add a return type to the function expression.
-        protected fnExpressionProtected = function foo(cb = function(){ }) { return 0; }
-                                                            ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:153:52: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:153:57: Add a return type to the function expression.
-        protected fnArrowProtected = (cb = function(){ }) => "S";
-                                           ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:154:35: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:154:40: Add a return type to the function expression.
-    
-        static fnStaticExpression = function foo(cb = function(){ }) { return 0; }
-                                                      ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:156:46: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:156:51: Add a return type to the function expression.
-        static fnStaticArrow = (cb = function(){ }) => "S";
-                                     ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:157:29: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:157:34: Add a return type to the function expression.
-        protected static fnStaticExpressionProtected = function foo(cb = function(){ }) { return 0; }    
-                                                                         ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:158:65: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:158:70: Add a return type to the function expression.
-        protected static fnStaticArrowProtected = (cb = function(){ }) => "S";
-                                                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:159:48: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:159:53: Add a return type to the function expression.
-    
-        // Have annotation on owner
-        fnExpressionMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
-                                                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:162:48: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:162:53: Add a return type to the function expression.
-        fnArrowMethodHasReturn = (cb = function(){ }): string => "S";
-                                       ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:163:31: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:163:36: Add a return type to the function expression.
-        protected fnExpressionProtectedMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
-                                                                           ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:164:67: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:164:72: Add a return type to the function expression.
-        protected fnArrowProtectedMethodHasReturn = (cb = function(){ }): string => "S";
-                                                          ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:165:50: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:165:55: Add a return type to the function expression.
-    
-        static fnStaticExpressionMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
-                                                                     ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:167:61: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:167:66: Add a return type to the function expression.
-        static fnStaticArrowMethodHasReturn = (cb = function(){ }): string => "S";
-                                                    ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:168:44: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:168:49: Add a return type to the function expression.
-        protected static fnStaticExpressionProtectedMethodHasReturn = function foo(cb = function(){ }): number { return 0; }    
-                                                                                        ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:169:80: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:169:85: Add a return type to the function expression.
-        protected static fnStaticArrowProtectedMethodHasReturn = (cb = function(){ }): string => "S";
-                                                                       ~~~~~~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:170:63: Add a type annotation to the parameter cb.
-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:170:68: Add a return type to the function expression.
-    
-        // Have annotation only on parameter
-        fnExpressionOnlyOnParam = function foo(cb = function(): void { }) { return 0; }
-        fnArrowOnlyOnParam = (cb = function(): void { }) => "S";
-        protected fnExpressionProtectedOnlyOnParam = function foo(cb = function(): void { }) { return 0; }
-        protected fnArrowProtectedOnlyOnParam = (cb = function(): void { }) => "S";
-    
-        static fnStaticExpressionOnlyOnParam = function foo(cb = function(): void{ }) { return 0; }
-        static fnStaticArrowOnlyOnParam = (cb = function(): void{ }) => "S";
-        protected static fnStaticExpressionProtectedOnlyOnParam = function foo(cb = function(): void{ }) { return 0; }    
-        protected static fnStaticArrowProtectedOnlyOnParam = (cb = function(): void{ }) => "S";
-    
-        // Have annotation, so ok 
-        fnExpressionOk = function foo(cb = function(): void { }): number { return 0; }
-        fnArrowOK = (cb = function(): void { }): string => "S";
-        protected fnExpressionProtectedOk = function foo(cb = function(): void { }): number { return 0; }
-        protected fnArrowProtectedOK = (cb = function(): void { }): string => "S";
-    
-        static fnStaticExpressionOk = function foo(cb = function(): void{ }): number { return 0; }
-        static fnStaticArrowOk = (cb = function(): void{ }): string => "S";
-        protected static fnStaticExpressionProtectedOk = function foo(cb = function(): void{ }): number { return 0; }    
-        protected static fnStaticArrowProtectedOk = (cb = function(): void{ }): string => "S";
-        
-    
-        // No Error, not in declarations
-        private fnExpressionPrivate = function foo(cb = function(){ }) { return 0; }
-        private fnArrowPrivate = (cb = function(){ }) => "S";
-        #fnArrow = (cb = function(){ }) => "S";
-        #fnExpression = function foo(cb = function(){ }) { return 0;}
-        private static fnStaticExpressionPrivate = function foo(cb = function(){ }) { return 0; }
-        private static fnStaticArrowPrivate = (cb = function(){ }) => "S";
-    }
-    
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt.diff
new file mode 100644
index 00000000000..211aeb1d58e
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.errors.txt.diff
@@ -0,0 +1,365 @@
+--- old.isolatedDeclarationErrorsReturnTypes.errors.txt
++++ new.isolatedDeclarationErrorsReturnTypes.errors.txt
+@@= skipped -0, +0 lines =@@
+-isolatedDeclarationErrorsReturnTypes.ts(13,45): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(16,41): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(19,41): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(109,65): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(112,61): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(115,61): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(119,83): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(120,66): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(122,79): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(123,62): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(125,79): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(126,62): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(138,73): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(141,69): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(144,69): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(151,38): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(152,21): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(153,57): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(154,40): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(156,51): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(157,34): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(158,70): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(159,53): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(162,53): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(163,36): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(164,72): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(165,55): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(167,66): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(168,49): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(169,85): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-isolatedDeclarationErrorsReturnTypes.ts(170,68): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-
+-
+-==== isolatedDeclarationErrorsReturnTypes.ts (31 errors) ====
+-    // Function Variables
+-    export const fnExpressionConstVariable = function foo() { return 0;}
+-    export const fnArrowConstVariable = () => "S";
+-    
+-    export let fnExpressionLetVariable = function foo() { return 0;}
+-    export let fnArrowLetVariable = () => "S";
+-    
+-    export var fnExpressionVarVariable = function foo() { return 0;}
+-    export var fnArrowVarVariable = () => "S";
+-    
+-    // No Errors
+-    export const fnExpressionConstVariableOk = function foo(): number { return 0;}
+-    export const fnArrowConstVariableOk = (cb = function(){ }): string => "S";
+-                                                ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:13:40: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:13:45: Add a return type to the function expression.
+-    
+-    export let fnExpressionLetVariableOk = function foo(): number { return 0;}
+-    export let fnArrowLetVariableOk = (cb = function(){ }): string => "S";
+-                                            ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:16:36: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:16:41: Add a return type to the function expression.
+-    
+-    export var fnExpressionVarVariableOk = function foo(): number { return 0;}
+-    export var fnArrowVarVariableOk = (cb = function(){ }): string => "S";
+-                                            ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:19:36: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:19:41: Add a return type to the function expression.
+-    
+-    // Not exported
+-    const fnExpressionConstVariableInternal = function foo() { return 0;}
+-    const fnArrowConstVariableInternal = () => "S";
+-    
+-    let fnExpressionLetVariableInternal = function foo() { return 0;}
+-    let fnArrowLetVariableInternal = () => "S";
+-    
+-    var fnExpressionVarVariableInternal = function foo() { return 0;}
+-    var fnArrowVarVariableInternal = () => "S";
+-    
+-    // Function Fields
+-    export class ExportedClass { 
+-        // Should Error
+-        fnExpression = function foo() { return 0; }
+-        fnArrow = () => "S";    
+-        protected fnExpressionProtected = function foo() { return 0; }
+-        protected fnArrowProtected = () => "S";
+-    
+-        static fnStaticExpression = function foo() { return 0; }
+-        static fnStaticArrow = () => "S";
+-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
+-        protected static fnStaticArrowProtected = () => "S";
+-    
+-        // Have annotation, so ok 
+-        fnExpressionOk = function foo(): number { return 0; }
+-        fnArrowOK = (): string => "S";
+-        protected fnExpressionProtectedOk = function foo(): number { return 0; }
+-        protected fnArrowProtectedOK = (): string => "S";
+-    
+-        static fnStaticExpressionOk = function foo(): number { return 0; }
+-        static fnStaticArrowOk = (): string => "S";
+-        protected static fnStaticExpressionProtectedOk = function foo(): number { return 0; }    
+-        protected static fnStaticArrowProtectedOk = (): string => "S";
+-        
+-    
+-        // No Error not in declarations
+-        private fnExpressionPrivate = function foo() { return 0; }
+-        private fnArrowPrivate = () => "S";
+-        #fnArrow = () => "S";
+-        #fnExpression = function foo() { return 0;}
+-        private static fnStaticExpressionPrivate = function foo() { return 0; }
+-        private static fnStaticArrowPrivate = () => "S";
+-    }
+-    
+-    // Should error
+-    class IndirectlyExportedClass { 
+-        fnExpression = function foo() { return 0; }
+-        fnArrow = () => "S";
+-    
+-        static fnStaticExpression = function foo() { return 0; }
+-        static fnStaticArrow = () => "S";
+-        
+-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
+-        protected static fnStaticArrowProtected = () => "S";
+-    
+-        private fnExpressionPrivate = function foo() { return 0; }
+-        private fnArrowPrivate = () => "S";
+-        #fnArrow = () => "S";
+-        #fnExpression = function foo() { return 0;}
+-        private static fnStaticExpressionPrivate = function foo() { return 0; }
+-        private static fnStaticArrowPrivate = () => "S";
+-    }
+-    export const instance: IndirectlyExportedClass = new IndirectlyExportedClass();
+-    
+-    // No Errors
+-    class InternalClass { 
+-        fnExpression = function foo() { return 0; }
+-        fnArrow = () => "S";
+-    
+-        static fnStaticExpression = function foo() { return 0; }
+-        static fnStaticArrow = () => "S";
+-        
+-        protected static fnStaticExpressionProtected = function foo() { return 0; }    
+-        protected static fnStaticArrowProtected = () => "S";
+-    
+-        private fnExpressionPrivate = function foo() { return 0; }
+-        private fnArrowPrivate = () => "S";
+-        #fnArrow = () => "S";
+-        #fnExpression = function foo() { return 0;}
+-        private static fnStaticExpressionPrivate = function foo() { return 0; }
+-        private static fnStaticArrowPrivate = () => "S";
+-    }
+-    const internalInstance: InternalClass = new InternalClass();
+-    
+-    
+-    // Function parameters
+-    
+-    // In Function Variables - No annotations
+-    export const fnParamExpressionConstVariable = function foo(cb = function(){ }) { return 0;}
+-                                                                    ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:109:60: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:109:65: Add a return type to the function expression.
+-    export const fnParamArrowConstVariable = (cb = () => 1) => "S";
+-    
+-    export let fnParamExpressionLetVariable = function foo(cb = function(){ }) { return 0;}
+-                                                                ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:112:56: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:112:61: Add a return type to the function expression.
+-    export let fnParamArrowLetVariable = (cb = () => 1) => "S";
+-    
+-    export var fnParamExpressionVarVariable = function foo(cb = function(){ }) { return 0;}
+-                                                                ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:115:56: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:115:61: Add a return type to the function expression.
+-    export var fnParamArrowVarVariable = (cb = () => 1) => "S";
+-    
+-    // In Function Variables - No annotations on parameter
+-    export const fnParamExpressionConstVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
+-                                                                                      ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:119:78: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:119:83: Add a return type to the function expression.
+-    export const fnParamArrowConstVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
+-                                                                     ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:120:61: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:120:66: Add a return type to the function expression.
+-    
+-    export let fnParamExpressionLetVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
+-                                                                                  ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:122:74: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:122:79: Add a return type to the function expression.
+-    export let fnParamArrowLetVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
+-                                                                 ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:123:57: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:123:62: Add a return type to the function expression.
+-    
+-    export var fnParamExpressionVarVariableOwnerHasReturnType = function foo(cb = function(){ }): number { return 0;}
+-                                                                                  ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:125:74: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:125:79: Add a return type to the function expression.
+-    export var fnParamArrowVarVariableOwnerHasReturnType = (cb = function(){ }): string => "S";
+-                                                                 ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:126:57: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:126:62: Add a return type to the function expression.
+-    
+-    // No Errors
+-    export const fnParamExpressionConstVariableOk = function foo(cb = function(): void{ }): number { return 0;}
+-    export const fnParamArrowConstVariableOk = (cb = function(): void{ }): string => "S";
+-    
+-    export let fnParamExpressionLetVariableOk = function foo(cb = function(): void{ }): number { return 0;}
+-    export let fnParamArrowLetVariableOk = (cb = function(): void{ }): string => "S";
+-    
+-    export var fnParamExpressionVarVariableOk = function foo(cb = function(): void{ }): number { return 0;}
+-    export var fnParamArrowVarVariableOk = (cb = function(): void{ }): string => "S";
+-    
+-    export const fnParamExpressionConstVariableInternal = function foo(cb = function(){ }) { return 0;}
+-                                                                            ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:138:68: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:138:73: Add a return type to the function expression.
+-    export const fnParamArrowConstVariableInternal = (cb = () => 1) => "S";
+-    
+-    export let fnParamExpressionLetVariableInternal = function foo(cb = function(){ }) { return 0;}
+-                                                                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:141:64: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:141:69: Add a return type to the function expression.
+-    export let fnParamArrowLetVariableInternal = (cb = () => 1) => "S";
+-    
+-    export var fnParamExpressionVarVariableInternal = function foo(cb = function(){ }) { return 0;}
+-                                                                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:144:64: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:144:69: Add a return type to the function expression.
+-    export var fnParamArrowVarVariableInternal = (cb = () => 1) => "S";
+-    
+-    
+-    // In Function Fields
+-    export class FnParamsExportedClass { 
+-        // Should Error
+-        fnExpression = function foo(cb = function(){ }) { return 0; }
+-                                         ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:151:33: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:151:38: Add a return type to the function expression.
+-        fnArrow = (cb = function(){ }) => "S";
+-                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:152:16: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:152:21: Add a return type to the function expression.
+-        protected fnExpressionProtected = function foo(cb = function(){ }) { return 0; }
+-                                                            ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:153:52: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:153:57: Add a return type to the function expression.
+-        protected fnArrowProtected = (cb = function(){ }) => "S";
+-                                           ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:154:35: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:154:40: Add a return type to the function expression.
+-    
+-        static fnStaticExpression = function foo(cb = function(){ }) { return 0; }
+-                                                      ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:156:46: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:156:51: Add a return type to the function expression.
+-        static fnStaticArrow = (cb = function(){ }) => "S";
+-                                     ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:157:29: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:157:34: Add a return type to the function expression.
+-        protected static fnStaticExpressionProtected = function foo(cb = function(){ }) { return 0; }    
+-                                                                         ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:158:65: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:158:70: Add a return type to the function expression.
+-        protected static fnStaticArrowProtected = (cb = function(){ }) => "S";
+-                                                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:159:48: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:159:53: Add a return type to the function expression.
+-    
+-        // Have annotation on owner
+-        fnExpressionMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
+-                                                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:162:48: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:162:53: Add a return type to the function expression.
+-        fnArrowMethodHasReturn = (cb = function(){ }): string => "S";
+-                                       ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:163:31: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:163:36: Add a return type to the function expression.
+-        protected fnExpressionProtectedMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
+-                                                                           ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:164:67: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:164:72: Add a return type to the function expression.
+-        protected fnArrowProtectedMethodHasReturn = (cb = function(){ }): string => "S";
+-                                                          ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:165:50: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:165:55: Add a return type to the function expression.
+-    
+-        static fnStaticExpressionMethodHasReturn = function foo(cb = function(){ }): number { return 0; }
+-                                                                     ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:167:61: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:167:66: Add a return type to the function expression.
+-        static fnStaticArrowMethodHasReturn = (cb = function(){ }): string => "S";
+-                                                    ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:168:44: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:168:49: Add a return type to the function expression.
+-        protected static fnStaticExpressionProtectedMethodHasReturn = function foo(cb = function(){ }): number { return 0; }    
+-                                                                                        ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:169:80: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:169:85: Add a return type to the function expression.
+-        protected static fnStaticArrowProtectedMethodHasReturn = (cb = function(){ }): string => "S";
+-                                                                       ~~~~~~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9028 isolatedDeclarationErrorsReturnTypes.ts:170:63: Add a type annotation to the parameter cb.
+-!!! related TS9030 isolatedDeclarationErrorsReturnTypes.ts:170:68: Add a return type to the function expression.
+-    
+-        // Have annotation only on parameter
+-        fnExpressionOnlyOnParam = function foo(cb = function(): void { }) { return 0; }
+-        fnArrowOnlyOnParam = (cb = function(): void { }) => "S";
+-        protected fnExpressionProtectedOnlyOnParam = function foo(cb = function(): void { }) { return 0; }
+-        protected fnArrowProtectedOnlyOnParam = (cb = function(): void { }) => "S";
+-    
+-        static fnStaticExpressionOnlyOnParam = function foo(cb = function(): void{ }) { return 0; }
+-        static fnStaticArrowOnlyOnParam = (cb = function(): void{ }) => "S";
+-        protected static fnStaticExpressionProtectedOnlyOnParam = function foo(cb = function(): void{ }) { return 0; }    
+-        protected static fnStaticArrowProtectedOnlyOnParam = (cb = function(): void{ }) => "S";
+-    
+-        // Have annotation, so ok 
+-        fnExpressionOk = function foo(cb = function(): void { }): number { return 0; }
+-        fnArrowOK = (cb = function(): void { }): string => "S";
+-        protected fnExpressionProtectedOk = function foo(cb = function(): void { }): number { return 0; }
+-        protected fnArrowProtectedOK = (cb = function(): void { }): string => "S";
+-    
+-        static fnStaticExpressionOk = function foo(cb = function(): void{ }): number { return 0; }
+-        static fnStaticArrowOk = (cb = function(): void{ }): string => "S";
+-        protected static fnStaticExpressionProtectedOk = function foo(cb = function(): void{ }): number { return 0; }    
+-        protected static fnStaticArrowProtectedOk = (cb = function(): void{ }): string => "S";
+-        
+-    
+-        // No Error, not in declarations
+-        private fnExpressionPrivate = function foo(cb = function(){ }) { return 0; }
+-        private fnArrowPrivate = (cb = function(){ }) => "S";
+-        #fnArrow = (cb = function(){ }) => "S";
+-        #fnExpression = function foo(cb = function(){ }) { return 0;}
+-        private static fnStaticExpressionPrivate = function foo(cb = function(){ }) { return 0; }
+-        private static fnStaticArrowPrivate = (cb = function(){ }) => "S";
+-    }
+-    
++<no content>
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js
index 8dd9ad0d8a0..b51c38dc6d2 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js
@@ -361,3 +361,119 @@ export class FnParamsExportedClass {
     static fnStaticExpressionPrivate = function foo(cb = function () { }) { return 0; };
     static fnStaticArrowPrivate = (cb = function () { }) => "S";
 }
+
+
+//// [isolatedDeclarationErrorsReturnTypes.d.ts]
+export declare const fnExpressionConstVariable: () => number;
+export declare const fnArrowConstVariable: () => string;
+export declare let fnExpressionLetVariable: () => number;
+export declare let fnArrowLetVariable: () => string;
+export declare var fnExpressionVarVariable: () => number;
+export declare var fnArrowVarVariable: () => string;
+export declare const fnExpressionConstVariableOk: () => number;
+export declare const fnArrowConstVariableOk: (cb?: () => void) => string;
+export declare let fnExpressionLetVariableOk: () => number;
+export declare let fnArrowLetVariableOk: (cb?: () => void) => string;
+export declare var fnExpressionVarVariableOk: () => number;
+export declare var fnArrowVarVariableOk: (cb?: () => void) => string;
+export declare class ExportedClass {
+    #private;
+    fnExpression: () => number;
+    fnArrow: () => string;
+    protected fnExpressionProtected: () => number;
+    protected fnArrowProtected: () => string;
+    static fnStaticExpression: () => number;
+    static fnStaticArrow: () => string;
+    protected static fnStaticExpressionProtected: () => number;
+    protected static fnStaticArrowProtected: () => string;
+    fnExpressionOk: () => number;
+    fnArrowOK: () => string;
+    protected fnExpressionProtectedOk: () => number;
+    protected fnArrowProtectedOK: () => string;
+    static fnStaticExpressionOk: () => number;
+    static fnStaticArrowOk: () => string;
+    protected static fnStaticExpressionProtectedOk: () => number;
+    protected static fnStaticArrowProtectedOk: () => string;
+    private fnExpressionPrivate;
+    private fnArrowPrivate;
+    private static fnStaticExpressionPrivate;
+    private static fnStaticArrowPrivate;
+}
+declare class IndirectlyExportedClass {
+    #private;
+    fnExpression: () => number;
+    fnArrow: () => string;
+    static fnStaticExpression: () => number;
+    static fnStaticArrow: () => string;
+    protected static fnStaticExpressionProtected: () => number;
+    protected static fnStaticArrowProtected: () => string;
+    private fnExpressionPrivate;
+    private fnArrowPrivate;
+    private static fnStaticExpressionPrivate;
+    private static fnStaticArrowPrivate;
+}
+export declare const instance: IndirectlyExportedClass;
+export declare const fnParamExpressionConstVariable: (cb?: () => void) => number;
+export declare const fnParamArrowConstVariable: (cb?: () => number) => string;
+export declare let fnParamExpressionLetVariable: (cb?: () => void) => number;
+export declare let fnParamArrowLetVariable: (cb?: () => number) => string;
+export declare var fnParamExpressionVarVariable: (cb?: () => void) => number;
+export declare var fnParamArrowVarVariable: (cb?: () => number) => string;
+export declare const fnParamExpressionConstVariableOwnerHasReturnType: (cb?: () => void) => number;
+export declare const fnParamArrowConstVariableOwnerHasReturnType: (cb?: () => void) => string;
+export declare let fnParamExpressionLetVariableOwnerHasReturnType: (cb?: () => void) => number;
+export declare let fnParamArrowLetVariableOwnerHasReturnType: (cb?: () => void) => string;
+export declare var fnParamExpressionVarVariableOwnerHasReturnType: (cb?: () => void) => number;
+export declare var fnParamArrowVarVariableOwnerHasReturnType: (cb?: () => void) => string;
+export declare const fnParamExpressionConstVariableOk: (cb?: () => void) => number;
+export declare const fnParamArrowConstVariableOk: (cb?: () => void) => string;
+export declare let fnParamExpressionLetVariableOk: (cb?: () => void) => number;
+export declare let fnParamArrowLetVariableOk: (cb?: () => void) => string;
+export declare var fnParamExpressionVarVariableOk: (cb?: () => void) => number;
+export declare var fnParamArrowVarVariableOk: (cb?: () => void) => string;
+export declare const fnParamExpressionConstVariableInternal: (cb?: () => void) => number;
+export declare const fnParamArrowConstVariableInternal: (cb?: () => number) => string;
+export declare let fnParamExpressionLetVariableInternal: (cb?: () => void) => number;
+export declare let fnParamArrowLetVariableInternal: (cb?: () => number) => string;
+export declare var fnParamExpressionVarVariableInternal: (cb?: () => void) => number;
+export declare var fnParamArrowVarVariableInternal: (cb?: () => number) => string;
+export declare class FnParamsExportedClass {
+    #private;
+    fnExpression: (cb?: () => void) => number;
+    fnArrow: (cb?: () => void) => string;
+    protected fnExpressionProtected: (cb?: () => void) => number;
+    protected fnArrowProtected: (cb?: () => void) => string;
+    static fnStaticExpression: (cb?: () => void) => number;
+    static fnStaticArrow: (cb?: () => void) => string;
+    protected static fnStaticExpressionProtected: (cb?: () => void) => number;
+    protected static fnStaticArrowProtected: (cb?: () => void) => string;
+    fnExpressionMethodHasReturn: (cb?: () => void) => number;
+    fnArrowMethodHasReturn: (cb?: () => void) => string;
+    protected fnExpressionProtectedMethodHasReturn: (cb?: () => void) => number;
+    protected fnArrowProtectedMethodHasReturn: (cb?: () => void) => string;
+    static fnStaticExpressionMethodHasReturn: (cb?: () => void) => number;
+    static fnStaticArrowMethodHasReturn: (cb?: () => void) => string;
+    protected static fnStaticExpressionProtectedMethodHasReturn: (cb?: () => void) => number;
+    protected static fnStaticArrowProtectedMethodHasReturn: (cb?: () => void) => string;
+    fnExpressionOnlyOnParam: (cb?: () => void) => number;
+    fnArrowOnlyOnParam: (cb?: () => void) => string;
+    protected fnExpressionProtectedOnlyOnParam: (cb?: () => void) => number;
+    protected fnArrowProtectedOnlyOnParam: (cb?: () => void) => string;
+    static fnStaticExpressionOnlyOnParam: (cb?: () => void) => number;
+    static fnStaticArrowOnlyOnParam: (cb?: () => void) => string;
+    protected static fnStaticExpressionProtectedOnlyOnParam: (cb?: () => void) => number;
+    protected static fnStaticArrowProtectedOnlyOnParam: (cb?: () => void) => string;
+    fnExpressionOk: (cb?: () => void) => number;
+    fnArrowOK: (cb?: () => void) => string;
+    protected fnExpressionProtectedOk: (cb?: () => void) => number;
+    protected fnArrowProtectedOK: (cb?: () => void) => string;
+    static fnStaticExpressionOk: (cb?: () => void) => number;
+    static fnStaticArrowOk: (cb?: () => void) => string;
+    protected static fnStaticExpressionProtectedOk: (cb?: () => void) => number;
+    protected static fnStaticArrowProtectedOk: (cb?: () => void) => string;
+    private fnExpressionPrivate;
+    private fnArrowPrivate;
+    private static fnStaticExpressionPrivate;
+    private static fnStaticArrowPrivate;
+}
+export {};
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js.diff
new file mode 100644
index 00000000000..230a0d1c7ad
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationErrorsReturnTypes.js.diff
@@ -0,0 +1,122 @@
+--- old.isolatedDeclarationErrorsReturnTypes.js
++++ new.isolatedDeclarationErrorsReturnTypes.js
+@@= skipped -360, +360 lines =@@
+     static fnStaticExpressionPrivate = function foo(cb = function () { }) { return 0; };
+     static fnStaticArrowPrivate = (cb = function () { }) => "S";
+ }
++
++
++//// [isolatedDeclarationErrorsReturnTypes.d.ts]
++export declare const fnExpressionConstVariable: () => number;
++export declare const fnArrowConstVariable: () => string;
++export declare let fnExpressionLetVariable: () => number;
++export declare let fnArrowLetVariable: () => string;
++export declare var fnExpressionVarVariable: () => number;
++export declare var fnArrowVarVariable: () => string;
++export declare const fnExpressionConstVariableOk: () => number;
++export declare const fnArrowConstVariableOk: (cb?: () => void) => string;
++export declare let fnExpressionLetVariableOk: () => number;
++export declare let fnArrowLetVariableOk: (cb?: () => void) => string;
++export declare var fnExpressionVarVariableOk: () => number;
++export declare var fnArrowVarVariableOk: (cb?: () => void) => string;
++export declare class ExportedClass {
++    #private;
++    fnExpression: () => number;
++    fnArrow: () => string;
++    protected fnExpressionProtected: () => number;
++    protected fnArrowProtected: () => string;
++    static fnStaticExpression: () => number;
++    static fnStaticArrow: () => string;
++    protected static fnStaticExpressionProtected: () => number;
++    protected static fnStaticArrowProtected: () => string;
++    fnExpressionOk: () => number;
++    fnArrowOK: () => string;
++    protected fnExpressionProtectedOk: () => number;
++    protected fnArrowProtectedOK: () => string;
++    static fnStaticExpressionOk: () => number;
++    static fnStaticArrowOk: () => string;
++    protected static fnStaticExpressionProtectedOk: () => number;
++    protected static fnStaticArrowProtectedOk: () => string;
++    private fnExpressionPrivate;
++    private fnArrowPrivate;
++    private static fnStaticExpressionPrivate;
++    private static fnStaticArrowPrivate;
++}
++declare class IndirectlyExportedClass {
++    #private;
++    fnExpression: () => number;
++    fnArrow: () => string;
++    static fnStaticExpression: () => number;
++    static fnStaticArrow: () => string;
++    protected static fnStaticExpressionProtected: () => number;
++    protected static fnStaticArrowProtected: () => string;
++    private fnExpressionPrivate;
++    private fnArrowPrivate;
++    private static fnStaticExpressionPrivate;
++    private static fnStaticArrowPrivate;
++}
++export declare const instance: IndirectlyExportedClass;
++export declare const fnParamExpressionConstVariable: (cb?: () => void) => number;
++export declare const fnParamArrowConstVariable: (cb?: () => number) => string;
++export declare let fnParamExpressionLetVariable: (cb?: () => void) => number;
++export declare let fnParamArrowLetVariable: (cb?: () => number) => string;
++export declare var fnParamExpressionVarVariable: (cb?: () => void) => number;
++export declare var fnParamArrowVarVariable: (cb?: () => number) => string;
++export declare const fnParamExpressionConstVariableOwnerHasReturnType: (cb?: () => void) => number;
++export declare const fnParamArrowConstVariableOwnerHasReturnType: (cb?: () => void) => string;
++export declare let fnParamExpressionLetVariableOwnerHasReturnType: (cb?: () => void) => number;
++export declare let fnParamArrowLetVariableOwnerHasReturnType: (cb?: () => void) => string;
++export declare var fnParamExpressionVarVariableOwnerHasReturnType: (cb?: () => void) => number;
++export declare var fnParamArrowVarVariableOwnerHasReturnType: (cb?: () => void) => string;
++export declare const fnParamExpressionConstVariableOk: (cb?: () => void) => number;
++export declare const fnParamArrowConstVariableOk: (cb?: () => void) => string;
++export declare let fnParamExpressionLetVariableOk: (cb?: () => void) => number;
++export declare let fnParamArrowLetVariableOk: (cb?: () => void) => string;
++export declare var fnParamExpressionVarVariableOk: (cb?: () => void) => number;
++export declare var fnParamArrowVarVariableOk: (cb?: () => void) => string;
++export declare const fnParamExpressionConstVariableInternal: (cb?: () => void) => number;
++export declare const fnParamArrowConstVariableInternal: (cb?: () => number) => string;
++export declare let fnParamExpressionLetVariableInternal: (cb?: () => void) => number;
++export declare let fnParamArrowLetVariableInternal: (cb?: () => number) => string;
++export declare var fnParamExpressionVarVariableInternal: (cb?: () => void) => number;
++export declare var fnParamArrowVarVariableInternal: (cb?: () => number) => string;
++export declare class FnParamsExportedClass {
++    #private;
++    fnExpression: (cb?: () => void) => number;
++    fnArrow: (cb?: () => void) => string;
++    protected fnExpressionProtected: (cb?: () => void) => number;
++    protected fnArrowProtected: (cb?: () => void) => string;
++    static fnStaticExpression: (cb?: () => void) => number;
++    static fnStaticArrow: (cb?: () => void) => string;
++    protected static fnStaticExpressionProtected: (cb?: () => void) => number;
++    protected static fnStaticArrowProtected: (cb?: () => void) => string;
++    fnExpressionMethodHasReturn: (cb?: () => void) => number;
++    fnArrowMethodHasReturn: (cb?: () => void) => string;
++    protected fnExpressionProtectedMethodHasReturn: (cb?: () => void) => number;
++    protected fnArrowProtectedMethodHasReturn: (cb?: () => void) => string;
++    static fnStaticExpressionMethodHasReturn: (cb?: () => void) => number;
++    static fnStaticArrowMethodHasReturn: (cb?: () => void) => string;
++    protected static fnStaticExpressionProtectedMethodHasReturn: (cb?: () => void) => number;
++    protected static fnStaticArrowProtectedMethodHasReturn: (cb?: () => void) => string;
++    fnExpressionOnlyOnParam: (cb?: () => void) => number;
++    fnArrowOnlyOnParam: (cb?: () => void) => string;
++    protected fnExpressionProtectedOnlyOnParam: (cb?: () => void) => number;
++    protected fnArrowProtectedOnlyOnParam: (cb?: () => void) => string;
++    static fnStaticExpressionOnlyOnParam: (cb?: () => void) => number;
++    static fnStaticArrowOnlyOnParam: (cb?: () => void) => string;
++    protected static fnStaticExpressionProtectedOnlyOnParam: (cb?: () => void) => number;
++    protected static fnStaticArrowProtectedOnlyOnParam: (cb?: () => void) => string;
++    fnExpressionOk: (cb?: () => void) => number;
++    fnArrowOK: (cb?: () => void) => string;
++    protected fnExpressionProtectedOk: (cb?: () => void) => number;
++    protected fnArrowProtectedOK: (cb?: () => void) => string;
++    static fnStaticExpressionOk: (cb?: () => void) => number;
++    static fnStaticArrowOk: (cb?: () => void) => string;
++    protected static fnStaticExpressionProtectedOk: (cb?: () => void) => number;
++    protected static fnStaticArrowProtectedOk: (cb?: () => void) => string;
++    private fnExpressionPrivate;
++    private fnArrowPrivate;
++    private static fnStaticExpressionPrivate;
++    private static fnStaticArrowPrivate;
++}
++export {};
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt
index 812ec2c1bea..941d9aa3a36 100644
--- a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt
@@ -1,4 +1,3 @@
-isolatedDeclarationLazySymbols.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
 isolatedDeclarationLazySymbols.ts(13,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
 isolatedDeclarationLazySymbols.ts(16,5): error TS1166: A computed property name in a class property declaration must have a simple literal type or a 'unique symbol' type.
 isolatedDeclarationLazySymbols.ts(16,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
@@ -6,11 +5,8 @@ isolatedDeclarationLazySymbols.ts(21,5): error TS9038: Computed property names o
 isolatedDeclarationLazySymbols.ts(22,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
 
 
-==== isolatedDeclarationLazySymbols.ts (6 errors) ====
+==== isolatedDeclarationLazySymbols.ts (5 errors) ====
     export function foo() {
-                    ~~~
-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
-!!! related TS9031 isolatedDeclarationLazySymbols.ts:1:17: Add a return type to the function declaration.
     
     }
     
diff --git a/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt.diff b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt.diff
new file mode 100644
index 00000000000..b22f956dcf4
--- /dev/null
+++ b/testdata/baselines/reference/submodule/compiler/isolatedDeclarationLazySymbols.errors.txt.diff
@@ -0,0 +1,20 @@
+--- old.isolatedDeclarationLazySymbols.errors.txt
++++ new.isolatedDeclarationLazySymbols.errors.txt
+@@= skipped -0, +0 lines =@@
+-isolatedDeclarationLazySymbols.ts(1,17): error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+ isolatedDeclarationLazySymbols.ts(13,1): error TS9023: Assigning properties to functions without declaring them is not supported with --isolatedDeclarations. Add an explicit declaration for the properties assigned to this function.
+ isolatedDeclarationLazySymbols.ts(16,5): error TS1166: A computed property name in a class property declaration must have a simple literal type or a 'unique symbol' type.
+ isolatedDeclarationLazySymbols.ts(16,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+@@= skipped -5, +4 lines =@@
+ isolatedDeclarationLazySymbols.ts(22,5): error TS9038: Computed property names on class or object literals cannot be inferred with --isolatedDeclarations.
+
+
+-==== isolatedDeclarationLazySymbols.ts (6 errors) ====
++==== isolatedDeclarationLazySymbols.ts (5 errors) ====
+     export function foo() {
+-                    ~~~
+-!!! error TS9007: Function must have an explicit return type annotation with --isolatedDeclarations.
+-!!! related TS9031 isolatedDeclarationLazySymbols.ts:1:17: Add a return type to the function declaration.
+     
+     }
+     
\ No newline at end of file