[llvm] Normalize file path to fix problems with different folder separators. (PR #215225)

[James Henderson via llvm-commits]

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@@ -85,22 +85,22 @@ static std::string applySubstitutePaths(StringRef FileName) {
   if (SubstitutePaths.empty())
     return FileName.str();
 
+  // FileName is normalized by the caller, so the components split out of it are
+  // normalized too. Only the rules given on the command line still need it.
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jh7370 wrote:

I wonder if this comment is indicating that we should normalize the values during argument parsing and storing rather than at this late point of use? If we did that, we wouldn't need this comment at all.

https://github.com/llvm/llvm-project/pull/215225