[clang] [clang][analyzer] Forward CTU-import failure conditions (PR #189064)

[Balázs Benics via cfe-commits]

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@@ -330,7 +353,9 @@ llvm::Expected<const T *> CrossTranslationUnitContext::getCrossTUDefinitionImpl(
   // different dialects of C++.
   if (LangTo.CPlusPlus != LangFrom.CPlusPlus) {
     ++NumLangMismatch;
-    return llvm::make_error<IndexError>(index_error_code::lang_mismatch);
+    return llvm::make_error<IndexError>(
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steakhal wrote:

This is not for you, but we should have just used createStringError (i think thats how its called) here instead of coming up with newer and newer error  message patterns.

https://github.com/llvm/llvm-project/pull/189064