Fix wrong code generation for this-> in lambda type parameters#4955
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SeanTAllen wants to merge 1 commit intomainfrom
Open
Fix wrong code generation for this-> in lambda type parameters#4955SeanTAllen wants to merge 1 commit intomainfrom
this-> in lambda type parameters#4955SeanTAllen wants to merge 1 commit intomainfrom
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Lambda types like `{(this->A!): Bool}` are desugared into anonymous
interfaces during the sugar pass. The desugaring preserved `this->`
verbatim, but inside the generated interface, `this` refers to the
interface's own receiver rather than the enclosing class's receiver.
This semantic mismatch caused incorrect structural subtype checks,
leading to wrong vtable dispatch, incorrect results, or segfaults
when the lambda was forwarded to another function.
The fix resolves `this->` to the enclosing method's receiver cap
during lambda type desugaring. Since the compiler already enforces
that `this->` can only appear in `box` methods, `{(this->A!)}` now
correctly desugars to `{(box->A!)}`.
Closes #4168
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When a lambda type contains
this->(e.g.,{(this->A!): Bool}), the sugar pass desugars it into an anonymous interface. The desugaring preservedthis->verbatim, but inside the generated interface,thisrefers to the interface's own receiver rather than the enclosing class's receiver. This caused incorrect structural subtype checks, leading to wrong vtable dispatch, incorrect results, or segfaults when the lambda was forwarded to another function rather than called directly.The fix resolves
this->to the enclosing method's receiver cap during lambda type desugaring, so{(this->A!)}in aboxmethod correctly becomes{(box->A!)}.Closes #4168