Fix #12789 syntaxError on valid template code (#6457)

Author: chrchr-github

lib/token.cpp

@@ -965,7 +965,7 @@ const Token * Token::findClosingBracket() const
             depth -= 2;
         }
         // save named template parameter
-        else if (templateParameter && depth == 1 && closing->str() == "," &&
+        else if (templateParameter && depth == 1 && Token::Match(closing, "[,=]") &&
                  closing->previous()->isName() && !Match(closing->previous(), "class|typename|."))
             templateParameters.insert(closing->strAt(-1));
     }

test/testtoken.cpp

@@ -108,6 +108,7 @@ class TestToken : public TestFixture {
         TEST_CASE(canFindMatchingBracketsWithTooManyOpening);
         TEST_CASE(findClosingBracket);
         TEST_CASE(findClosingBracket2);
+        TEST_CASE(findClosingBracket3);
 
         TEST_CASE(expressionString);
 
@@ -1157,6 +1158,14 @@ class TestToken : public TestFixture {
         ASSERT(t && Token::simpleMatch(t->findClosingBracket(), ">"));
     }
 
+    void findClosingBracket3() {
+        const SimpleTokenizer var(*this, // #12789
+                                  "template <size_t I = 0, typename... ArgsT, std::enable_if_t<I < sizeof...(ArgsT)>* = nullptr>\n"
+                                  "void f();\n");
+        const Token* const t = Token::findsimplematch(var.tokens(), "<");
+        ASSERT(t && Token::simpleMatch(t->findClosingBracket(), ">"));
+    }
+
     void expressionString() {
         const SimpleTokenizer var1(*this, "void f() { *((unsigned long long *)x) = 0; }");
         const Token *const tok1 = Token::findsimplematch(var1.tokens(), "*");