Fix #14520: false positive: passedByValue on declaration with const (cppcheck-opensource#8460)

Co-authored-by: Oliver Stöneberg <firewave@users.noreply.github.com>

Author: ludviggunne

lib/checkother.cpp

@@ -1591,6 +1591,21 @@ void CheckOther::checkPassByReference()
         if (var->isArray() && (!var->isStlType() || Token::simpleMatch(var->nameToken()->next(), "[")))
             continue;
 
+        if (var->isArgument()) {
+            const Token *tok = var->typeStartToken();
+            for (; tok; tok = tok->next()) {
+                if (Token::simpleMatch(tok, "(")) {
+                    tok = tok->link();
+                    continue;
+                }
+                if (Token::simpleMatch(tok, ")"))
+                    break;
+            }
+
+            if (Token::simpleMatch(tok, ") ;"))
+                continue;
+        }
+
         const bool isConst = var->isConst();
         if (isConst) {
             passedByValueError(var, inconclusive, isRangeBasedFor);

test/testother.cpp

@@ -2911,6 +2911,9 @@ class TestOther : public TestFixture {
         ASSERT_EQUALS("", errout_str());
 
         check("struct X { int a[5]; }; void f(const X v);");
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct X { int a[5]; }; void f(const X v) { (void) v; }");
         ASSERT_EQUALS("[test.cpp:1:40]: (performance) Function parameter 'v' should be passed by const reference. [passedByValue]\n", errout_str());
 
         check("extern \"C\" { struct X { int a[5]; }; void f(const X v); }");
@@ -4109,6 +4112,14 @@ class TestOther : public TestFixture {
               "    if (*pp) {}\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("class C {\n"
+              "public:\n"
+              "    explicit C(const std::string s);\n"
+              "private:\n"
+              "    std::string _s;\n"
+              "};\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void constParameterCallback() {