Fix dynamic event-assignment decompilation leaking is-event opcode#3873
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Fix dynamic event-assignment decompilation leaking is-event opcode#3873siegfriedpammer wants to merge 1 commit into
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DynamicIsEventInstruction has no ExpressionBuilder visitor, so any is-event diamond that survives the transform pipeline leaks as an "OpCode not supported" comment. The collapse only fired for the plain statement form; every other lowering the compiler emits for "d.Event += b" was missed: - a copy-of-value temporary between the getmember cache and the diamond (modern Roslyn emits it for the statement form), - the result-used shape, where the diamond is a value-if nested inside the consuming expression (a call argument, or a leave's value when returned), - the result-returned shape as two leaves, "if (isevent) leave(add)" plus a fall-through "leave(compound)" rather than an if/else, and - the same two-leaves shape when the optimizer drops the getmember cache (legacy csc and Roslyn <= 2.x): the is-event flag then feeds a single branch, inlining folds it into the condition, and the compound leave is already collapsed, so the cache-based entry never matched it and the branch leaked. These compilers only run on Windows CI, so the gap was invisible on Linux. The descendants walk handles the nested value-if once an over-strict copy-of-value bounds guard (which never held for the compact return block) is dropped. The two two-leaves shapes share a skeleton matcher and the add/remove accessor-name check, and both validate the accessor name and arguments. Re-running from the collapsed statement instead of the next one avoids indexing past the end of a block that has shrunk to a single leave. Assisted-by: Claude:claude-opus-4-8:Claude Code
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DynamicIsEventInstructionhas noExpressionBuildervisitor, so any is-event diamond that survives the transform pipeline leaks into the output as an "OpCode not supported: DynamicIsEventInstruction" comment.DynamicIsEventAssignmentTransformonly collapsed the plain statement form ofd.Event += b. The three other lowerings the compiler emits were missed and leaked:Console.WriteLine(d.Event += b), or aleave's value when returned);if (isevent) leave(add)plus a fall-throughleave(compound)rather than an if/else.The descendants walk now handles the nested value-if once an over-strict copy-of-value bounds guard (which never held for the compact 4-instruction return block) is dropped; the two-leaves shape gets a dedicated matcher. Re-running from the collapsed statement instead of the next one avoids indexing past the end of a block that has shrunk to a single
leave.New
DynamicTestsfixture cases cover the statement, result-used, and result-returned forms; the last is green across all compiler-matrix configs (optimized configs exercise the two-leaves matcher, debug configs the nested value-if path).🤖 Generated with Claude Code