Fix #15079 FP syntaxError for C-style cast before scope operator

The check added in a294079 (#15060) reports every `)` followed by `::`
unless the `(` belongs to a control flow keyword or decltype. That also
rejects valid code like `(HWND)::SendMessage(...)` or placement new
`new (p) ::N::T`, so whole translation units are skipped.

Only report when the parenthesis follows a non-keyword name, which is the
unknown macro case the check was added for.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: autoantwort

lib/tokenize.cpp

@@ -9177,9 +9177,11 @@ void Tokenizer::findGarbageCode() const
             if (!Token::Match(tok->next(), "%name%|*|~") || (tok->next()->isKeyword() && !Token::Match(tok->next(), "new|delete|operator")))
                 syntaxError(tok);
             if (Token::simpleMatch(tok->tokAt(-1), ")")) {
+                // NAME(...)::  => NAME is most likely an unknown macro
+                // other cases are valid, e.g. (void)::f(), return (T)::x, new (p) ::T, decltype(x)::type
                 const Token* const prev = tok->linkAt(-1)->tokAt(-1);
-                if (!Token::Match(prev, "%name% (") || (!prev->isControlFlowKeyword() && prev->str() != "decltype")) {
-                    if (prev && prev->isUpperCaseName())
+                if (Token::Match(prev, "%name% (") && !prev->isKeyword()) {
+                    if (prev->isUpperCaseName())
                         unknownMacroError(prev);
                     else
                         syntaxError(tok);

test/testtokenize.cpp

@@ -8135,6 +8135,22 @@ class TestTokenizer : public TestFixture {
                                              "    *p = -*p;\n"
                                              "}\n"));
 
+        ASSERT_NO_THROW(tokenizeAndStringify("void f(void* h) {\n" // cast before global scope operator
+                                             "    (void)::CloseHandle(h);\n"
+                                             "    int i = (int)::GetTickCount();\n"
+                                             "    g((unsigned char)::toupper(i));\n"
+                                             "}\n"));
+        ASSERT_NO_THROW(tokenizeAndStringify("int f(int i) {\n"
+                                             "    return (int)::abs(i);\n"
+                                             "}\n"));
+        ASSERT_NO_THROW(tokenizeAndStringify("namespace N { struct T {}; }\n"
+                                             "void f(void* p) {\n"
+                                             "    new (p) ::N::T;\n"
+                                             "}\n"));
+        ASSERT_NO_THROW(tokenizeAndStringify("struct S { using type = int; };\n"
+                                             "S s;\n"
+                                             "decltype(s)::type i;\n"));
+
         ignore_errout();
 
         ASSERT_EQUALS(";", tokenizeAndStringify("typedef std::size_t size_t;\n")); // #14809