[PATCH] D73020: [Sema] Perform call checking when building CXXNewExpr

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

Looks good if you change the error to a warning.



================
Comment at: clang/lib/Sema/SemaChecking.cpp:3887-3891
         if (!I.isPowerOf2()) {
           Diag(Arg->getExprLoc(), diag::err_alignment_not_power_of_two)
               << Arg->getSourceRange();
           return;
         }
----------------
Oh, I wasn't aware we gave an error for this case. We can't issue an error for passing a bad alignment to `operator new` -- it's valid for code to pass a bad alignment, but results in undefined behavior. The same is true for `aligned_alloc` and `posix_memalign`, so we should presumably just downgrade this from an error to a warning in general rather than (say) treating `operator new` as a special case.

For example, this is valid and may be reasonable in some cases:

```
template<int N> void *make() {
  if ((N & (N-1)) == 0)
    return operator new(N, std::align_val_t(N));
  else
    return operator new(N);
}
void *p = make<7>();
```


Repository:
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  https://reviews.llvm.org/D73020/new/

https://reviews.llvm.org/D73020