[clang-tools-extra] Use resolved path when filtering in IncludeInserter (PR #148371)

[Nathan Ridge via cfe-commits]

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@@ -344,6 +344,21 @@ TEST_F(HeadersTest, ShortenIncludesInSearchPathBracketed) {
   EXPECT_EQ(calculate(BarHeader), "<sub/bar.h>");
 }
 
+TEST_F(HeadersTest, ShortenIncludesInSearchPathBracketedFilterByFullPath) {
+  // The filter receives the full path of the header, so it is able to filter by
+  // the parent directory, even if it is part of the include search path
+  AngledHeaders.push_back([](auto Path) {
+#if defined(_WIN32)
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HighCommander4 wrote:

It's a bit unfortunate that users have to use different path separators on different platforms in the pattern; it seems like that would inhibit a cross-platform project being able to check in a `.clangd` file containing this configuration key.

What do you think about using `convert_to_slash` (similar to [here](https://searchfox.org/llvm/rev/ab6923b9b7a75de79ee06b400ae73771e130339e/clang-tools-extra/clangd/Headers.cpp#301)) to normalize the path to forward-slashes before checking it against the regex?

https://github.com/llvm/llvm-project/pull/148371