Fix #9806 (False positive: template function can be static) (#2868)

* Include detecting variadic template functions by matching against endTok instead of startTok.
* Add argument count check for variadic (template) member functions.

lib/checkclass.cpp

@@ -1925,7 +1925,9 @@ bool CheckClass::isMemberFunc(const Scope *scope, const Token *tok) const
                     else
                         break;
                 }
-                if (argsPassed == func.argCount() || (argsPassed < func.argCount() && argsPassed >= func.minArgCount()))
+                if (argsPassed == func.argCount() ||
+                    (func.isVariadic() && argsPassed >= (func.argCount() - 1)) ||
+                    (argsPassed < func.argCount() && argsPassed >= func.minArgCount()))
                     return true;
             }
         }

lib/symboldatabase.cpp

@@ -3681,8 +3681,8 @@ void Function::addArguments(const SymbolDatabase *symbolDatabase, const Scope *s
         argumentList.emplace_back(nameTok, startTok, endTok, count++, AccessControl::Argument, argType, functionScope, symbolDatabase->mSettings);
 
         if (tok->str() == ")") {
-            // check for a variadic function
+            // check for a variadic function or a variadic template function
-            if (Token::simpleMatch(startTok, "..."))
+            if (Token::simpleMatch(endTok, "..."))
                 isVariadic(true);
 
             break;

test/testclass.cpp

@@ -171,6 +171,8 @@ private:
         TEST_CASE(const66); // ticket #7714
         TEST_CASE(const67); // ticket #9193
         TEST_CASE(const68); // ticket #6471
+        TEST_CASE(const69); // ticket #9806
+        TEST_CASE(const70); // variadic template can receive more arguments than in its definition
         TEST_CASE(const_handleDefaultParameters);
         TEST_CASE(const_passThisToMemberOfOtherClass);
         TEST_CASE(assigningPointerToPointerIsNotAConstOperation);
@@ -5534,6 +5536,38 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void const69() { // #9806
+        checkConst("struct A {\n"
+                   "    int a = 0;\n"
+                   "    template <typename... Args> void call(const Args &... args) { a = 1; }\n"
+                   "    template <typename T, typename... Args> auto call(const Args &... args) -> T {\n"
+                   "        a = 2;\n"
+                   "        return T{};\n"
+                   "    }\n"
+                   "};\n"
+                   "\n"
+                   "struct B : public A {\n"
+                   "    void test() {\n"
+                   "        call();\n"
+                   "        call<int>(1, 2, 3);\n"
+                   "    }\n"
+                   "};");
+        ASSERT_EQUALS("", errout.str());
+    }
+
+    void const70() {
+        checkConst("struct A {\n"
+                   "    template <typename... Args> void call(Args ... args) {\n"
+                   "        func(this);\n"
+                   "    }\n"
+                   "\n"
+                   "    void test() {\n"
+                   "        call(1, 2);\n"
+                   "    }\n"
+                   "};");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void const_handleDefaultParameters() {
         checkConst("struct Foo {\n"
                    "    void foo1(int i, int j = 0) {\n"