Translate implicit casts from integer, pointer, and enum to bool (#56)

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -965,12 +965,8 @@ bool Converter::VisitReturnStmt(clang::ReturnStmt *stmt) {
 }
 
 void Converter::ConvertCondition(clang::Expr *cond) {
-  if (!cond->getType()->isBooleanType()) {
-    PushExprKind push(*this, ExprKind::RValue);
-    Convert(CreateConversionToBool(cond, ctx_));
-    return;
-  }
-  Convert(cond);
+  PushExprKind push(*this, ExprKind::RValue);
+  Convert(NormalizeToBool(cond, ctx_));
 }
 
 bool Converter::VisitIfStmt(clang::IfStmt *stmt) {
@@ -1741,6 +1737,41 @@ void Converter::ConvertIntegerToEnumeralCast(clang::Expr *to,
   }
 }
 
+void Converter::ConvertIntegralToBooleanCast(clang::ImplicitCastExpr *expr) {
+  auto sub_expr = expr->getSubExpr();
+  auto *stripped = sub_expr->IgnoreParenImpCasts();
+
+  if (auto binop = clang::dyn_cast<clang::BinaryOperator>(stripped)) {
+    // Comparison already produces bool, no wrap needed.
+    if (binop->isComparisonOp()) {
+      Convert(sub_expr);
+      return;
+    }
+    // Distribute bool conversion to each argument of the logical op.
+    if (binop->isLogicalOp()) {
+      {
+        PushParen paren(*this);
+        ConvertCondition(binop->getLHS());
+      }
+      StrCat(binop->getOpcodeStr());
+      {
+        PushParen paren(*this);
+        ConvertCondition(binop->getRHS());
+      }
+      return;
+    }
+  }
+
+  PushParen paren(*this);
+  Convert(sub_expr);
+  StrCat(token::kDiff);
+  if (sub_expr->getType()->isEnumeralType()) {
+    StrCat(GetUnsafeTypeAsString(sub_expr->getType()), "::from(0)");
+  } else /* sub_expr->getType()->isIntegerType() */ {
+    StrCat(token::kZero);
+  }
+}
+
 bool Converter::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
   auto *sub_expr = expr->getSubExpr();
   auto type = expr->getType();
@@ -1816,20 +1847,7 @@ bool Converter::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
     Convert(sub_expr);
     break;
   case clang::CastKind::CK_IntegralToBoolean:
-    if (auto binop = clang::dyn_cast<clang::BinaryOperator>(
-            sub_expr->IgnoreParenImpCasts())) {
-      // This already produces bool, no need for != 0
-      if (binop->isComparisonOp()) {
-        Convert(sub_expr);
-        break;
-      }
-    }
-
-    {
-      PushParen paren(*this);
-      Convert(sub_expr);
-      StrCat(token::kDiff, token::kZero);
-    }
+    ConvertIntegralToBooleanCast(expr);
     break;
   case clang::CastKind::CK_PointerToBoolean:
     StrCat(token::kNot);
@@ -2130,6 +2148,18 @@ bool Converter::VisitUnaryOperator(clang::UnaryOperator *expr) {
     Convert(sub_expr);
     computed_expr_type_ = ComputedExprType::FreshValue;
     break;
+  case clang::UO_LNot: {
+    bool needs_int_cast =
+        expr->getType()->isIntegerType() && !expr->getType()->isBooleanType();
+    PushParen paren_cast(*this, needs_int_cast);
+    StrCat(token::kNot);
+    ConvertCondition(sub_expr);
+    if (needs_int_cast) {
+      ConvertCast(expr->getType());
+    }
+    computed_expr_type_ = ComputedExprType::FreshValue;
+    break;
+  }
   case clang::UO_Minus:
     if (auto *literal = clang::dyn_cast<clang::IntegerLiteral>(sub_expr)) {
       if (sub_expr->getType()->isUnsignedIntegerType()) {
@@ -2173,7 +2203,7 @@ void Converter::EmitStmtExprTail(clang::Expr *tail) { Convert(tail); }
 
 bool Converter::VisitConditionalOperator(clang::ConditionalOperator *expr) {
   StrCat(keyword::kIf);
-  Convert(expr->getCond());
+  ConvertCondition(expr->getCond());
   {
     PushBrace then_brace(*this);
     if (expr->isLValue() && !isRValue() && !expr->getType()->isFunctionType()) {
@@ -2290,21 +2320,11 @@ bool Converter::VisitParenExpr(clang::ParenExpr *expr) {
     }
   }
 
-  // Add cast to avoid ambigous integers. Don't add cast if sub expression is a
-  // pointer dereference because we might want to mutate the dereferenced value.
-  bool should_add_integral_cast =
-      expr->getType()->isIntegralOrEnumerationType() && !isAddrOf() &&
-      !isVoid() && !clang::isa<clang::UnaryOperator>(expr->getSubExpr());
-  PushParen outer(*this, should_add_integral_cast);
-
   {
     PushParen inner(*this);
     Convert(expr->getSubExpr());
   }
 
-  if (should_add_integral_cast) {
-    ConvertCast(expr->getType());
-  }
   return false;
 }
 

cpp2rust/converter/converter.h

@@ -243,6 +243,8 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   void ConvertIntegerToEnumeralCast(clang::Expr *to, clang::Expr *from);
 
+  void ConvertIntegralToBooleanCast(clang::ImplicitCastExpr *expr);
+
   virtual bool VisitImplicitCastExpr(clang::ImplicitCastExpr *expr);
 
   virtual bool VisitExplicitCastExpr(clang::ExplicitCastExpr *expr);

cpp2rust/converter/converter_lib.cpp

@@ -683,9 +683,32 @@ bool ContainsVAArgExpr(const clang::Stmt *stmt) {
   return false;
 }
 
-clang::Expr *CreateConversionToBool(clang::Expr *expr, clang::ASTContext &ctx) {
+clang::Expr *NormalizeToBool(clang::Expr *expr, clang::ASTContext &ctx) {
+  if (expr->getType()->isBooleanType()) {
+    return expr;
+  }
+
+  // If logical not returns integer, then craft a new logical not that returns
+  // bool.
+  if (auto bin = clang::dyn_cast<clang::UnaryOperator>(expr)) {
+    if (bin->getOpcode() == clang::UO_LNot) {
+      return clang::UnaryOperator::Create(
+          ctx, bin->getSubExpr(), clang::UO_LNot, ctx.BoolTy, clang::VK_PRValue,
+          clang::OK_Ordinary, clang::SourceLocation(), false,
+          clang::FPOptionsOverride());
+    }
+  }
+
+  // Either to pointer -> bool, or int -> bool.
+  clang::CastKind cast_kind;
+  if (expr->getType()->isPointerType()) {
+    cast_kind = clang::CK_PointerToBoolean;
+  } else /* expr->getType()->isIntegerType() */ {
+    cast_kind = clang::CK_IntegralToBoolean;
+  }
+
   return clang::ImplicitCastExpr::Create(
-      ctx, ctx.BoolTy, clang::CK_IntegralToBoolean, expr,
+      ctx, ctx.BoolTy, cast_kind, expr,
       /*BasePath=*/nullptr, clang::VK_PRValue, clang::FPOptionsOverride());
 }
 

cpp2rust/converter/converter_lib.h

@@ -154,7 +154,7 @@ bool IsBuiltinVaCopy(const clang::CallExpr *expr);
 
 bool ContainsVAArgExpr(const clang::Stmt *stmt);
 
-clang::Expr *CreateConversionToBool(clang::Expr *expr, clang::ASTContext &ctx);
+clang::Expr *NormalizeToBool(clang::Expr *expr, clang::ASTContext &ctx);
 
 std::vector<clang::SwitchCase *>
 GetTopLevelSwitchCases(clang::SwitchStmt *stmt);

cpp2rust/converter/models/converter_refcount.cpp

@@ -615,7 +615,8 @@ bool ConverterRefCount::ConvertIncAndDec(clang::UnaryOperator *expr) {
 
 bool ConverterRefCount::VisitConditionalOperator(
     clang::ConditionalOperator *expr) {
-  StrCat(keyword::kIf, ConvertRValue(expr->getCond()));
+  StrCat(keyword::kIf);
+  ConvertCondition(expr->getCond());
   {
     PushBrace then_brace(*this);
     StrCat(ConvertFresh(expr->getTrueExpr()));
@@ -1046,9 +1047,12 @@ bool ConverterRefCount::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
     }
   }
 
-  if (expr->getCastKind() == clang::CastKind::CK_NullToPointer &&
-      expr->getType()->isFunctionPointerType()) {
-    StrCat("FnPtr::null()");
+  if (expr->getCastKind() == clang::CastKind::CK_NullToPointer) {
+    if (expr->getType()->isFunctionPointerType()) {
+      StrCat("FnPtr::null()");
+    } else {
+      StrCat("Default::default()");
+    }
     computed_expr_type_ = ComputedExprType::FreshPointer;
     return false;
   }
@@ -1137,6 +1141,11 @@ bool ConverterRefCount::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
     }
     return false;
   }
+  if (expr->getCastKind() == clang::CK_NullToPointer) {
+    StrCat("Default::default()");
+    computed_expr_type_ = ComputedExprType::FreshPointer;
+    return false;
+  }
   switch (expr->getStmtClass()) {
   case clang::Stmt::CXXReinterpretCastExprClass:
     assert(expr->getType()->isPointerType() &&

tests/ub/out/refcount/ub4.rs

@@ -7,11 +7,10 @@ use std::io::{Read, Seek, Write};
 use std::os::fd::AsFd;
 use std::rc::{Rc, Weak};
 pub fn smaller_0(x1: Ptr<i32>, x2: Ptr<i32>) -> Ptr<i32> {
-    return if (({
+    return if ({
         let _lhs = (x1.read());
         _lhs < (x2.read())
-    }) as bool)
-    {
+    }) {
         (x1).clone()
     } else {
         (x2).clone()

tests/ub/out/unsafe/ub4.rs

@@ -7,11 +7,7 @@ use std::io::{Read, Seek, Write};
 use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
 use std::rc::Rc;
 pub unsafe fn smaller_0(x1: *mut i32, x2: *mut i32) -> *mut i32 {
-    return if (((*x1) < (*x2)) as bool) {
-        (x1)
-    } else {
-        (x2)
-    };
+    return if ((*x1) < (*x2)) { (x1) } else { (x2) };
 }
 pub fn main() {
     unsafe {

tests/unit/bool_condition_enum.cpp

@@ -0,0 +1,29 @@
+#include <assert.h>
+
+enum Code { CODE_OK = 0, CODE_ERR = 1, CODE_FATAL = 2 };
+
+int main() {
+  Code code = CODE_OK;
+  Code err = CODE_ERR;
+
+  if (code) {
+    assert(false);
+  }
+  if (!code) {
+    assert(true);
+  }
+  if (err) {
+    assert(true);
+  }
+  if (!err) {
+    assert(false);
+  }
+
+  int t9 = !code;
+  assert(t9 == 1);
+
+  bool b4 = code;
+  assert(!b4);
+
+  return 0;
+}

tests/unit/bool_condition_enum_c.c

@@ -0,0 +1,30 @@
+#include <assert.h>
+#include <stdbool.h>
+
+enum Code { CODE_OK = 0, CODE_ERR = 1, CODE_FATAL = 2 };
+
+int main() {
+  enum Code code = CODE_OK;
+  enum Code err = CODE_ERR;
+
+  if (code) {
+    assert(false);
+  }
+  if (!code) {
+    assert(true);
+  }
+  if (err) {
+    assert(true);
+  }
+  if (!err) {
+    assert(false);
+  }
+
+  int t9 = !code;
+  assert(t9 == 1);
+
+  bool b4 = code;
+  assert(!b4);
+
+  return 0;
+}

tests/unit/bool_condition_int.cpp

@@ -0,0 +1,63 @@
+#include <assert.h>
+
+int main() {
+  int n = 3;
+  int zero = 0;
+  unsigned u = 4;
+  unsigned long ul = 5;
+  long long ll = 6;
+  char ch = 'a';
+
+  if (n) {
+    assert(true);
+  }
+  if (!n) {
+    assert(false);
+  }
+  if (zero) {
+    assert(false);
+  }
+  if (!zero) {
+    assert(true);
+  }
+
+  if (u) {
+    assert(true);
+  }
+  if (ul) {
+    assert(true);
+  }
+  if (ll) {
+    assert(true);
+  }
+  if (ch) {
+    assert(true);
+  }
+
+  int loop_count = 0;
+  int counter = 3;
+  while (counter) {
+    --counter;
+    ++loop_count;
+  }
+  assert(loop_count == 3);
+
+  for (int i = 5; i; --i) {
+    ++loop_count;
+  }
+  assert(loop_count == 8);
+
+  int t = n ? 100 : 200;
+  assert(t == 100);
+  int t2 = zero ? 100 : 200;
+  assert(t2 == 200);
+  int t7 = !n;
+  assert(t7 == 0);
+  int t8 = !zero;
+  assert(t8 == 1);
+
+  bool b1 = n;
+  assert(b1);
+
+  return 0;
+}