[clang-tools-extra] [clangd][modules] Discover opened module files outside the compilation database (PR #218958)

[Chuanqi Xu via cfe-commits]

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@@ -865,11 +868,63 @@ class ModuleNameToSourceCache {
   llvm::StringMap<llvm::StringMap<std::string>> ModuleNameToMultipleSourceCache;
 };
 
+bool isCXXModuleFile(PathRef File) {
+  namespace types = clang::driver::types;
+  auto Lang =
+      types::lookupTypeForExtension(llvm::sys::path::extension(File).substr(1));
+  return Lang == types::TY_CXXModule;
+}
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ChuanqiXu9 wrote:

This is not accurate. But I can accept this as a compromise. Let's add a comment for it.

https://github.com/llvm/llvm-project/pull/218958