[clang] [Serialization] Check for stack exhaustion when reading declarations (PR #79875)

[Ilya Biryukov via cfe-commits]

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@@ -4099,7 +4099,9 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   // calls to Decl::getASTContext() by Decl's methods will find the
   // TranslationUnitDecl without crashing.
   D->setDeclContext(Context.getTranslationUnitDecl());
-  Reader.Visit(D);
+
+  // Reading some declarations can result in deep recursion.
+  SemaObj->runWithSufficientStackSpace(DeclLoc, [&] { Reader.Visit(D); });
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ilya-biryukov wrote:

Could you elaborate in which sense it is non-meaningful for the purpose of calling this method?
I believe SemaObj is never null here (because it's used during deserialization of declarations). The only logic we have in `runWithSufficientStackSpace`, is to warn about stack exhaustion only once and actually show this warning.

I would still be using `Wstack-exhausted` here, not sure there is much useful context to add here (maybe a note about deserializing declarations, but this case is so rare I think we can live without it).

https://github.com/llvm/llvm-project/pull/79875