Fix 12371: C++20: Requires clause on a constructor (#5972)

Author: pfultz2

lib/tokenize.cpp

@@ -6344,7 +6344,8 @@ void Tokenizer::removeMacrosInGlobalScope()
             while (Token::Match(tok2, "%type% (") && tok2->isUpperCaseName())
                 tok2 = tok2->linkAt(1)->next();
 
-            if (Token::Match(tok, "%name% (") && Token::Match(tok2, "%name% *|&|::|<| %name%") && !Token::Match(tok2, "namespace|class|struct|union|private:|protected:|public:"))
+            if (Token::Match(tok, "%name% (") && Token::Match(tok2, "%name% *|&|::|<| %name%") &&
+                !Token::Match(tok2, "requires|namespace|class|struct|union|private:|protected:|public:"))
                 unknownMacroError(tok);
 
             if (Token::Match(tok, "%type% (") && Token::Match(tok2, "%type% (") && !Token::Match(tok2, "noexcept|throw") && isFunctionHead(tok2->next(), ":;{"))

test/testtokenize.cpp

@@ -409,6 +409,7 @@ class TestTokenizer : public TestFixture {
         TEST_CASE(checkRefQualifiers);
         TEST_CASE(checkConditionBlock);
         TEST_CASE(checkUnknownCircularVar);
+        TEST_CASE(checkRequires);
 
         // #9052
         TEST_CASE(noCrash1);
@@ -7559,6 +7560,12 @@ class TestTokenizer : public TestFixture {
                                              "}\n"));
     }
 
+    void checkRequires()
+    {
+        ASSERT_NO_THROW(tokenizeAndStringify("template<class T, class U>\n"
+                                             "struct X { X(U) requires true {} };\n"));
+    }
+
     void noCrash1() {
         ASSERT_NO_THROW(tokenizeAndStringify(
                             "struct A {\n"