[clang] [Clang] Don't treat a declaration that declares nothing as an invalid statement (PR #224682)

[Akash Manna via cfe-commits]

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@@ -231,6 +231,11 @@ StmtResult Parser::ParseStatementOrDeclarationAfterAttributes(
                                    GNUAttrs.Range.getBegin());
       } else if (GNUAttrs.Range.getBegin().isValid())
         DeclStart = GNUAttrs.Range.getBegin();
+      // A declaration that declares nothing (`int;`) yields no Decl but still
+      // occupies the statement position; unlike a pragma, ParseStatement() must
+      // not skip it.
+      if (!Decl)
+        return Actions.ActOnNullStmt(PrevTokLocation);
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akash-manna-sky wrote:

I tried `EmptyDecl`, but it can't appear inside a function or class today. An invalid unnamed decl would make any struct containing `int;` invalid (`ActOnFields`), and CodeGen doesn't expect invalid decls since `int;` only warns. So I'd like to keep this PR as the crash fix. 


https://github.com/llvm/llvm-project/pull/224682