[all-commits] [llvm/llvm-project] c309dc: [Clang][Sema] placement new initializes typedef ar...

[mahtohappy via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c309dc6d0759b23b570c563f611530ff1a49e1bd
      https://github.com/llvm/llvm-project/commit/c309dc6d0759b23b570c563f611530ff1a49e1bd
  Author: mahtohappy <Happy.Kumar at Windriver.com>
  Date:   2024-04-16 (Tue, 16 Apr 2024)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/lib/Sema/TreeTransform.h
    A clang/test/SemaCXX/instantiate-new-placement-size.cpp

  Log Message:
  -----------
  [Clang][Sema] placement new initializes typedef array with correct size (#83124)

When in-place new-ing a local variable of an array of trivial type, the
generated code calls 'memset' with the correct size of the array,
earlier it was generating size (squared of the typedef array + size).

The cause: `typedef TYPE TArray[8]; TArray x;` The type of declarator is
Tarray[8] and in `SemaExprCXX.cpp::BuildCXXNew` we check if it's of
typedef and of constant size then we get the original type and it works
fine for non-dependent cases.
But in case of template we do `TreeTransform.h:TransformCXXNEWExpr` and
there we again check the allocated type which is TArray[8] and it stays
that way, so ArraySize=(Tarray[8] type, alloc Tarray[8*type]) so the
squared size allocation.

ArraySize gets calculated earlier in `TreeTransform.h` so that
`if(!ArraySize)` condition was failing.
fix: I changed that condition to `if(ArraySize)`. 


Fixes #41441



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