[clang] [clang] deduplicate target-features for modules (PR #187614)

[Florian Mayer via cfe-commits]

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@@ -495,7 +495,10 @@ static bool checkTargetOptions(const TargetOptions &TargetOpts,
   SmallVector<StringRef, 4> ReadFeatures(TargetOpts.FeaturesAsWritten.begin(),
                                          TargetOpts.FeaturesAsWritten.end());
   llvm::sort(ExistingFeatures);
+  ExistingFeatures.erase(llvm::unique(ExistingFeatures),
+                         ExistingFeatures.end());
   llvm::sort(ReadFeatures);
+  ReadFeatures.erase(llvm::unique(ReadFeatures), ReadFeatures.end());
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fmayer wrote:

my (cursory) understanding is that e.g. `+sse2` also implicitly `+sse`

https://github.com/llvm/llvm-project/pull/187614