[all-commits] [llvm/llvm-project] 4728d3: [clang] Reject references to vector types in `__bu...

[Akash Manna via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4728d3c8e911e9f67e8eaf2f6756364f10518560
      https://github.com/llvm/llvm-project/commit/4728d3c8e911e9f67e8eaf2f6756364f10518560
  Author: Akash Manna <akash.manna.mymail at gmail.com>
  Date:   2026-09-09 (Wed, 09 Sep 2026)

  Changed paths:
    M clang/docs/ReleaseNotes.md
    M clang/lib/Sema/SemaExpr.cpp
    M clang/test/SemaCXX/builtin_vectorelements.cpp
    M clang/test/SemaCXX/ptrauth-type-discriminator.cpp
    A clang/test/SemaOpenCLCXX/vec_step.clcpp

  Log Message:
  -----------
  [clang] Reject references to vector types in `__builtin_vectorelements` (#219767)

Fixes #216997

`__builtin_vectorelements` shares its operand check with `sizeof` and
friends, and that shared code looks through reference types before it
dispatches to the per-builtin check. So `__builtin_vectorelements(veci4
&)` was accepted by Sema, but the expression kept the reference as its
argument type, and everything downstream — constant evaluation, the
bytecode interpreter, CodeGen — expects that type to be a vector.
Constant-evaluating the initializer in the reproducer then trips
`assert(Ty->isSizelessVectorType())`. The alias syntax in the report
isn't the cause; `vec` there is a well-formed reference-to-vector type.

The check now runs before the reference is looked through, so a
reference to a vector type gets the existing "must be of vector type"
error, the same one `__builtin_vectorelements(int &)` already produced.
No other trait kind is affected.

LLM tools were used for this contribution. I've reviewed, built, and
tested the change myself before pushing to GitHub.



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