fix: wrong code generation for synthesized object hooks #1338
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Summary ======= Fix a bug with synthesis of lifetime-tracking hooks for object types using inheritance, which showed up as a C compiler error when using recent versions of clang or gcc. Details ======= When synthesizing the hooks for object types using inheritance, the destination accessor expression wasn't wrapped in an object conversion prior to emitting the super type handling. Without the conversion, the synthesized hook passed its own parameter directly to the call of the super type's hook. This is wrong in general (because the argument's type doesn't match the parameter's), but didn't cause concrete issues until gcc and clang started to disallow implicit conversions between incompatible pointer types.
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alaviss
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Jun 7, 2024
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I'm thinking that we should either add a {.passC.} or a config file to turn on -Werror=incompatible-pointer-types for this test
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The config file approach is already used by another test, but it's brittle and I'd rather not embrace it further.
I'll make a separate PR that adds debug functionality for pretty-printing the initial MIR, and then this test can make sure the MIR for the destroy hook is sensible.
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/merge |
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Merge requested by: @saem Contents after the first section break of the PR description has been removed and preserved below: |
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Summary
Fix a bug with synthesis of lifetime-tracking hooks for object types
using inheritance, which showed up as a C compiler error when using
recent versions of clang or gcc.
Fixes #1337.
Details
When synthesizing the hooks for object types using inheritance, the
destination accessor expression wasn't wrapped in an object conversion
prior to emitting the parent object handling.
Without the conversion, the synthesized hook passed along its own
parameter to the call of the super type's hook as-is. This is wrong
in general (the argument's type doesn't match the parameter's), but
didn't cause concrete issues until gcc and clang started to disallow
implicit conversions between incompatible pointer types.