[clang] [clang][Parser] Allow private type aliases in out-of-line member function return types (PR #169272)

[Vassil Vassilev via cfe-commits]

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@@ -61,8 +61,26 @@ bool Parser::isCXXDeclarationStatement(
           // token is also an identifier and assume a declaration.
           // We cannot check if the scopes match because the declarations could
           // involve namespaces and friend declarations.
-          if (NextToken().is(tok::identifier))
+          //
+          // Also handle cases like "A::B *foo" or "A::B &foo" where the type
+          // is followed by ptr/ref declarator operators. These patterns are
+          // very likely to be declarations (e.g., out-of-line member function
+          // definitions with pointer/reference return types).
+          Token Next = NextToken();
+          if (Next.is(tok::identifier))
             return true;
+          // Check for pointer/reference patterns: A::B *id, A::B &id, A::B &&id
+          // Also handles multiple indirections like A::B **id
+          if (Next.isOneOf(tok::star, tok::amp, tok::ampamp)) {
+            // Look ahead to see if there's an identifier after ptr/ref ops
+            RevertingTentativeParsingAction PA(*this);
+            ConsumeToken(); // consume the identifier (type name)
+            // Skip all consecutive *, &, && tokens (for cases like A::B **)
+            while (Tok.isOneOf(tok::star, tok::amp, tok::ampamp))
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vgvassilev wrote:

I presume the c++ scope specifier has been parsed already. In this case we should call a parser function rather than implementing some parsing by ourselves. You can trace what clang does for out-of-line definitions after calling `ParseOptionalCXXScopeSpecifier`. We should do the same and if that fails we know that this is not a declaration, more parsing will be required otherwise.

https://github.com/llvm/llvm-project/pull/169272