martinboehme wrote: > > As an initial comment, wanted to confirm that we've clarified what the > > semantics of the AST are here. > > In #128068, I asked: > > > What I'm not clear on is what the rule is that disambiguates this. Is it > > > simply that if a `CXXThisExpr` is contained in an `InitListExpr`, it > > > refers to the result object of that `InitListExpr` (and not the this > > > pointer of the enclosing `CXXMethodDecl`)? > > > > > > Have you been able to get a definitive clarification on this? > > @yronglin chimed in at [#128068 > (comment)](https://github.com/llvm/llvm-project/issues/128068#issuecomment-3013510399) > but haven't heard from others beyond that. > > What I see in the code / debugger is like that, involving > `CXXDefaultInitExpr`: "if a `CXXThisExpr` is contained in an > `CXXDefaultInitExpr` in an `InitListExpr` (or `CXXParenListInitExpr`) (and > not the...)". > > * while parsing and building an `InitListExpr` (one example is around > [here](https://github.com/llvm/llvm-project/blob/ace3d3002ff465d433dce526ad3b641170a3dda7/clang/lib/Parse/ParseExprCXX.cpp#L1799-L1805)) > * it will eventually hit > `FillInEmptyInitForField`[here](https://github.com/llvm/llvm-project/blob/e933cfcfb2d207a7ff63cf152a7a78555d431d49/clang/lib/Sema/SemaInit.cpp#L804-L824) > * and `BuildCXXDefaultInitExpr` will have an > [`CXXThisScopeRAII`](https://github.com/llvm/llvm-project/blob/dc8e89b2b3787defa9ef1d72014c8a68c1b09a5f/clang/lib/Sema/SemaExpr.cpp#L5650) > which sets > [`CXXThisTypeOverride`](https://github.com/llvm/llvm-project/blob/dc8e89b2b3787defa9ef1d72014c8a68c1b09a5f/clang/lib/Sema/SemaExprCXX.cpp#L1251) > with the `Field->getParent()`'s type > > similarly, there's some CodeGen code that prepares for a different `this` for > fields > [here](https://github.com/llvm/llvm-project/blob/ace3d3002ff465d433dce526ad3b641170a3dda7/clang/lib/CodeGen/CGExprAgg.cpp#L1845) > using > [`FieldConstructionScope`](https://github.com/llvm/llvm-project/blob/ace3d3002ff465d433dce526ad3b641170a3dda7/clang/lib/CodeGen/CodeGenFunction.h#L1759) > based on the slot for the InitListExpr [from > here](https://github.com/llvm/llvm-project/blob/ace3d3002ff465d433dce526ad3b641170a3dda7/clang/lib/CodeGen/CGExprAgg.cpp#L1785) > > If the `CXXThisExpr` is not under an `CXXDefaultInitExpr`, then you use the > "previous" this. [Example](https://godbolt.org/z/KdMno4qWf) where `this` for > `x` is type `Foo*` but `this` for `i` is `Other*`.
Sorry for the late reply -- was busy with other things. Thanks for gathering these references. I haven't looked at everything in detail, but this looks persuasive. However, I wonder if we could get some confirmation from a person who has worked with this code themselves -- maybe ask in the Clang Frontend section of the Clang forum? https://github.com/llvm/llvm-project/pull/146900 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
