[clang] [clang][ASTImporter] Invalidate ImportedTypes cache on Decl import failure (PR #214008)

[Balázs Benics via cfe-commits]

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@@ -10038,6 +10038,13 @@ Expected<Decl *> ASTImporter::Import(Decl *FromD) {
       auto *ToD = CreatedToD;
       ImportedDecls.erase(Pos);
 
+      // Also scrub the imported type mapping, if applicable. Import(Type*) can
+      // cache a type mapping to a declaration that ultimately fails.
+      if (const auto *FromTD = dyn_cast<TagDecl>(FromD))
+        if (const Type *FromTy =
+                getFromContext().getCanonicalTagType(FromTD).getTypePtr())
+          ImportedTypes.erase(FromTy);
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steakhal wrote:

It is likely subjective but how I read the llvm style guide is that if a single guarded statement does not align perfectly intuitively under the guarding if, then one must always use braces.

Here since there is a line break in the condition it disqualifies. Because that is discualified, the parent `if` is also disqualified from eliding the braces.

https://github.com/llvm/llvm-project/pull/214008