[clang] [Clang][RISCV] Recognize unsupport target feature by supporting isValidFeatureName (PR #106495)

[Piyou Chen via cfe-commits]

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@@ -257,7 +257,7 @@ bool RISCVTargetInfo::initFeatureMap(
 
   // If a target attribute specified a full arch string, override all the ISA
   // extension target features.
-  const auto I = llvm::find(FeaturesVec, "__RISCV_TargetAttrNeedOverride");
+  const auto I = llvm::find(FeaturesVec, "+__RISCV_TargetAttrNeedOverride");
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BeMg wrote:

This feature was used to implement the target attribute override mechanism.

I think it could be removed after replacing it with several negative target features. Here is the pull request for this change: https://github.com/llvm/llvm-project/pull/106680


https://github.com/llvm/llvm-project/pull/106495