[llvm] [llvm] Add format check for MCSubtargetFeatures (PR #180943)

[Craig Topper via llvm-commits]

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@@ -452,6 +477,8 @@ class Target {
                                          StringRef Features) const {
     if (!MCSubtargetInfoCtorFn)
       return nullptr;
+    if (!isValidFeatureListFormat(Features))
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topperc wrote:

The caller wouldn't have enough information to produce a helpful error message would it? Not sure how to fix that though.

https://github.com/llvm/llvm-project/pull/180943