[clang] [Clang] Implement P3034R1 Module Declarations Shouldn’t be Macros (PR #90574)

[via cfe-commits]

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@@ -2686,18 +2693,31 @@ bool Parser::ParseModuleName(
       }
 
       Diag(Tok, diag::err_module_expected_ident) << IsImport;
-      SkipUntil(tok::semi);
+      SkipUntil(tok::semi, StopBeforeMatch);
       return true;
     }
 
-    // Record this part of the module path.
-    Path.push_back(std::make_pair(Tok.getIdentifierInfo(), Tok.getLocation()));
+    Token Identifier = Tok;
     ConsumeToken();
 
-    if (Tok.isNot(tok::period))
-      return false;
+    // P3034R1: Module Declarations Shouldn’t be Macros.
+    const auto *MI = PP.getMacroInfo(Identifier.getIdentifierInfo());
+    if (!IsImport && MI) {
+      HasMacroInModuleName = true;
+      if (MI->isFunctionLike())
+        SkipUntil(tok::r_paren, tok::period, tok::colon,
+                  StopAtSemi | StopBeforeMatch);
+      Diag(Identifier, diag::err_module_decl_cannot_be_macros)
+          << Identifier.getLocation() << IsPartition << MI->isFunctionLike()
+          << Identifier.getIdentifierInfo();
+    } else if (!HasMacroInModuleName) {
+      // Record this part of the module path.
+      Path.push_back(std::make_pair(Identifier.getIdentifierInfo(),
+                                    Identifier.getLocation()));
+    }
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cor3ntin wrote:

Having a function-like macro name in a module.
It would not be treated as a macro name because function-like macro are only replaced when a `(` follows, which can never be the case here.

in the tests below, `export module A.FUNC_LIKE` should be a valid module name
(and `export module A.FUNC_LIKE()` should be ill-formed with an `(` cannot appear in a module name,
or you can have a custom diag explaining that macros are not expanded in module names)


https://github.com/llvm/llvm-project/pull/90574