[clang] [clang] Increase VecLib bitfield size to 4 bits in CodeGenOptions.def (PR #108804)

[Aaron Ballman via cfe-commits]

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@@ -375,8 +375,13 @@ ENUM_CODEGENOPT(Inlining, InliningMethod, 2, NormalInlining)
 /// The maximum stack size a function can have to be considered for inlining.
 VALUE_CODEGENOPT(InlineMaxStackSize, 32, UINT_MAX)
 
+// Ensure the VecLib bitfield has enough space for future vector libraries.
+// If new vector libraries are added beyond the current limit of 16, this static assertion will fail.
+static_assert(static_cast<int>(llvm::driver::VectorLibrary::NoLibrary) <= 16, 
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AaronBallman wrote:

This doesn't actually protect against anything because `NoLibrary` is the first enumerator, not the last one.

(Also, I suspect we're missing significant test coverage if we managed to add new libraries and zero tests failed as a result of the too-small bit-field.)

https://github.com/llvm/llvm-project/pull/108804