From cec4b11ce261866fc47089c4f6b92435eac70878 Mon Sep 17 00:00:00 2001
From: chrchr-github <78114321+chrchr-github@users.noreply.github.com>
Date: Wed, 21 Feb 2024 17:16:15 +0100
Subject: [PATCH] Fix #12447 FN cstyleCast when casting to reference (#5998)

---
 lib/checkother.cpp | 23 +++++++++++++++--------
 lib/checkother.h   |  2 +-
 test/testother.cpp | 19 +++++++++++++++----
 3 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 4438338b7bc..b588bfae75b 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -321,11 +321,17 @@ void CheckOther::warningOldStylePointerCast()
                 if (Token::simpleMatch(castTok, "<") && castTok->link())
                     castTok = castTok->link()->next();
             }
-            if (castTok == tok->next() || !Token::simpleMatch(castTok, "*"))
-                continue;
-            while (Token::Match(castTok, "*|const|&"))
+            if (castTok == tok->next())
+                continue;
+            bool isPtr = false, isRef = false;
+            while (Token::Match(castTok, "*|const|&")) {
+                if (castTok->str() == "*")
+                    isPtr = true;
+                else if (castTok->str() == "&")
+                    isRef = true;
                 castTok = castTok->next();
-            if (!Token::Match(castTok, ") (| %name%|%num%|%bool%|%char%|%str%|&"))
+            }
+            if ((!isPtr && !isRef) || !Token::Match(castTok, ") (| %name%|%num%|%bool%|%char%|%str%|&"))
                 continue;
 
             if (Token::Match(tok->previous(), "%type%"))
@@ -344,16 +350,17 @@ void CheckOther::warningOldStylePointerCast()
                 continue;
 
             if (typeTok->tokType() == Token::eType || typeTok->tokType() == Token::eName)
-                cstyleCastError(tok);
+                cstyleCastError(tok, isPtr);
         }
     }
 }
 
-void CheckOther::cstyleCastError(const Token *tok)
+void CheckOther::cstyleCastError(const Token *tok, bool isPtr)
 {
+    const std::string type = isPtr ? "pointer" : "reference";
     reportError(tok, Severity::style, "cstyleCast",
-                "C-style pointer casting\n"
-                "C-style pointer casting detected. C++ offers four different kinds of casts as replacements: "
+                "C-style " + type + " casting\n"
+                "C-style " + type + " casting detected. C++ offers four different kinds of casts as replacements: "
                 "static_cast, const_cast, dynamic_cast and reinterpret_cast. A C-style cast could evaluate to "
                 "any of those automatically, thus it is considered safer if the programmer explicitly states "
                 "which kind of cast is expected.", CWE398, Certainty::normal);
diff --git a/lib/checkother.h b/lib/checkother.h
index 5f52e3092d9..1b7d080e7e5 100644
--- a/lib/checkother.h
+++ b/lib/checkother.h
@@ -239,7 +239,7 @@ class CPPCHECKLIB CheckOther : public Check {
     void checkCastIntToCharAndBackError(const Token *tok, const std::string &strFunctionName);
     void clarifyCalculationError(const Token *tok, const std::string &op);
     void clarifyStatementError(const Token* tok);
-    void cstyleCastError(const Token *tok);
+    void cstyleCastError(const Token *tok, bool isPtr = true);
     void invalidPointerCastError(const Token* tok, const std::string& from, const std::string& to, bool inconclusive, bool toIsInt);
     void passedByValueError(const Variable* var, bool inconclusive, bool isRangeBasedFor = false);
     void constVariableError(const Variable *var, const Function *function);
diff --git a/test/testother.cpp b/test/testother.cpp
index fd0bd743878..c1b7260e9ac 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -1911,6 +1911,13 @@ class TestOther : public TestFixture {
                       "[test.cpp:8]: (style) C-style pointer casting\n"
                       "[test.cpp:9]: (style) C-style pointer casting\n",
                       errout.str());
+
+        // #12447
+        checkOldStylePointerCast("void f(const int& i) {\n"
+                                 "  int& r = (int&)i;\n"
+                                 "  r = 0;\n"
+                                 "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (style) C-style reference casting\n", errout.str());
     }
 
 #define checkInvalidPointerCast(...) checkInvalidPointerCast_(__FILE__, __LINE__, __VA_ARGS__)
@@ -2884,27 +2891,31 @@ class TestOther : public TestFixture {
               "    x.dostuff();\n"
               "    const U& y = (const U&)(x);\n"
               "}");
-        ASSERT_EQUALS("[test.cpp:2]: (style) Parameter 'x' can be declared as reference to const\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) C-style reference casting\n"
+                      "[test.cpp:2]: (style) Parameter 'x' can be declared as reference to const\n",
+                      errout.str());
         check("struct T : public U { void dostuff() const {}};\n"
               "void a(T& x) {\n"
               "    x.dostuff();\n"
               "    U& y = (U&)(x);\n"
               "    y.mutate();\n" // to avoid warnings that y can be const
               "}");
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) C-style reference casting\n", errout.str());
         check("struct T : public U { void dostuff() const {}};\n"
               "void a(T& x) {\n"
               "    x.dostuff();\n"
               "    const U& y = (typename const U&)(x);\n"
               "}");
-        ASSERT_EQUALS("[test.cpp:2]: (style) Parameter 'x' can be declared as reference to const\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) C-style reference casting\n"
+                      "[test.cpp:2]: (style) Parameter 'x' can be declared as reference to const\n",
+                      errout.str());
         check("struct T : public U { void dostuff() const {}};\n"
               "void a(T& x) {\n"
               "    x.dostuff();\n"
               "    U& y = (typename U&)(x);\n"
               "    y.mutate();\n" // to avoid warnings that y can be const
               "}");
-        ASSERT_EQUALS("", errout.str());
+        ASSERT_EQUALS("[test.cpp:4]: (style) C-style reference casting\n", errout.str());
         check("struct T : public U { void dostuff() const {}};\n"
               "void a(T& x) {\n"
               "    x.dostuff();\n"