[clang] [clang][NFC] Factor out VLA checks in type traits (PR #88646)

[Vlad Serebrennikov via cfe-commits]

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@@ -5012,6 +5012,20 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
   return From;
 }
 
+/// Checks that type T is not a VLA.
+///
+/// @returns @c true if @p T is VLA and a diagnostic was emitted,
+/// @c false otherwise.
+static bool DiagnoseVLAInCXXTypeTrait(Sema &S, const TypeSourceInfo *T,
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Endilll wrote:

One reason might be the fact that current use case for this function is C++ traits specifically, since VLA is clearly an extension for them. I'll keep the `CXX` then.

https://github.com/llvm/llvm-project/pull/88646