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

[Piyou Chen via cfe-commits]

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@@ -391,7 +391,14 @@ void RISCVTargetInfo::fillValidTuneCPUList(
 
 static void handleFullArchString(StringRef FullArchStr,
                                  std::vector<std::string> &Features) {
-  Features.push_back("__RISCV_TargetAttrNeedOverride");
+
+  // Should be full arch string.
+  if (!FullArchStr.starts_with("rv")) {
+    Features.push_back(FullArchStr.str());
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BeMg wrote:

Oh, I found the `parseArchString` also check whether FullArchStr start with "rv". 

I removed this statement and drop the unnecessary "+" sign to trigger the Sema check.

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