Fix #10315 FP functionConst (#3997)

* Fix #10315 FP functionConst

* Update releasenotes.txt

lib/checkclass.cpp

@@ -2207,8 +2207,12 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, bool&
             if (v && v->isMutable())
                 continue;
 
-            if (tok1->str() == "this" && tok1->previous()->isAssignmentOp())
+            if (tok1->str() == "this") {
+                if (tok1->previous()->isAssignmentOp())
                     return false;
+                if (Token::Match(tok1->previous(), "( this . * %var% )")) // call using ptr to member function TODO: check constness
+                    return false;
+            }
 
             // non const pointer cast
             if (tok1->valueType() && tok1->valueType()->pointer > 0 && tok1->astParent() && tok1->astParent()->isCast() && !Token::simpleMatch(tok1->astParent(), "( const"))

releasenotes.txt

@@ -12,3 +12,5 @@ release notes for cppcheck-2.8
 - Detect more statements with constStatement
 - Detect variableScope for more types
 - Improvements to unreadVariable
+- Detect more instances of C style casts
+- Warn if the return value of new is discarded

test/testclass.cpp

@@ -194,6 +194,7 @@ private:
         TEST_CASE(const75); // ticket #10065
         TEST_CASE(const76); // ticket #10825
         TEST_CASE(const77); // ticket #10307
+        TEST_CASE(const78); // ticket #10315
         TEST_CASE(const_handleDefaultParameters);
         TEST_CASE(const_passThisToMemberOfOtherClass);
         TEST_CASE(assigningPointerToPointerIsNotAConstOperation);
@@ -6041,6 +6042,26 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void const78() { // #10315
+        checkConst("struct S {\n"
+                   "    typedef void(S::* F)();\n"
+                   "    void g(F f);\n"
+                   "};\n"
+                   "void S::g(F f) {\n"
+                   "    (this->*f)();\n"
+                   "}\n");
+        ASSERT_EQUALS("", errout.str());
+
+        checkConst("struct S {\n"
+                   "    using F = void(S::*)();\n"
+                   "    void g(F f);\n"
+                   "};\n"
+                   "void S::g(F f) {\n"
+                   "    (this->*f)();\n"
+                   "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void const_handleDefaultParameters() {
         checkConst("struct Foo {\n"
                    "    void foo1(int i, int j = 0) {\n"