Fix FP functionConst with ternary (#4874)

Author: chrchr-github

lib/checkclass.cpp

@@ -2347,6 +2347,10 @@ bool CheckClass::checkConstFunc(const Scope *scope, const Function *func, bool&
             const Token* lhs = tok1->previous();
             if (lhs->str() == "(" && tok1->astParent() && tok1->astParent()->astParent())
                 lhs = tok1->astParent()->astParent();
+            else if (lhs->str() == "?" && lhs->astParent())
+                lhs = lhs->astParent();
+            else if (lhs->str() == ":" && lhs->astParent() && lhs->astParent()->astParent() && lhs->astParent()->str() == "?")
+                lhs = lhs->astParent()->astParent();
             if (lhs->str() == "&") {
                 lhs = lhs->previous();
                 if (lhs->isAssignmentOp() && lhs->previous()->variable()) {

test/testclass.cpp

@@ -195,6 +195,7 @@ class TestClass : public TestFixture {
         TEST_CASE(const79); // ticket #9861
         TEST_CASE(const80); // ticket #11328
         TEST_CASE(const81); // ticket #11330
+        TEST_CASE(const82);
         TEST_CASE(const_handleDefaultParameters);
         TEST_CASE(const_passThisToMemberOfOtherClass);
         TEST_CASE(assigningPointerToPointerIsNotAConstOperation);
@@ -6321,6 +6322,23 @@ class TestClass : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void const82() {
+        checkConst("struct S {\n"
+                   "    int i1, i2;\n"
+                   "    void f(bool b);\n"
+                   "    void g(bool b, int j);\n"
+                   "};\n"
+                   "void S::f(bool b) {\n"
+                   "    int& r = b ? i1 : i2;\n"
+                   "    r = 5;\n"
+                   "}\n"
+                   "void S::g(bool b, int j) {\n"
+                   "    int& r = b ? j : i2;\n"
+                   "    r = 5;\n"
+                   "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void const_handleDefaultParameters() {
         checkConst("struct Foo {\n"
                    "    void foo1(int i, int j = 0) {\n"