Fix #14161 FN constVariablePointer (assignment to const pointer) (danmar#7859)

Co-authored-by: chrchr-github <noreply@github.com>

Author: chrchr-github

lib/astutils.cpp

@@ -1062,7 +1062,7 @@ bool isAliasOf(const Token *tok, nonneg int varid, bool* inconclusive)
     return false;
 }
 
-bool isAliasOf(const Token* tok, const Token* expr, int* indirect)
+bool isAliasOf(const Token* tok, const Token* expr, nonneg int* indirect)
 {
     const Token* r = nullptr;
     if (indirect)
@@ -2906,7 +2906,7 @@ static bool isExpressionChangedAt(const F& getExprTok,
                 // TODO: Is global variable really changed by function call?
                 return true;
         }
-        int i = 1;
+        nonneg int i = 1;
         bool aliased = false;
         // If we can't find the expression then assume it is an alias
         auto expr = getExprTok();
@@ -2916,7 +2916,10 @@ static bool isExpressionChangedAt(const F& getExprTok,
             aliased = isAliasOf(tok, expr, &i);
         if (!aliased)
             return false;
-        if (isVariableChanged(tok, indirect + i, settings, depth))
+        i += indirect;
+        if (tok->valueType() && tok->valueType()->pointer)
+            i = std::min(i, tok->valueType()->pointer);
+        if (isVariableChanged(tok, i, settings, depth))
             return true;
         // TODO: Try to traverse the lambda function
         if (Token::Match(tok, "%var% ("))

lib/astutils.h

@@ -379,7 +379,7 @@ bool isExpressionChangedAt(const Token* expr,
 /// If token is an alias if another variable
 bool isAliasOf(const Token *tok, nonneg int varid, bool* inconclusive = nullptr);
 
-bool isAliasOf(const Token* tok, const Token* expr, int* indirect = nullptr);
+bool isAliasOf(const Token* tok, const Token* expr, nonneg int* indirect = nullptr);
 
 const Token* getArgumentStart(const Token* ftok);
 

lib/checkother.cpp

@@ -1916,8 +1916,13 @@ void CheckOther::checkConstPointer()
                 continue;
             if (Token::simpleMatch(parent, "(") && Token::Match(parent->astOperand1(), "if|while"))
                 continue;
-            if (Token::simpleMatch(parent, "=") && parent->astOperand1() == tok)
-                continue;
+            if (Token::simpleMatch(parent, "=")) {
+                const Token* lhs = parent->astOperand1();
+                if (lhs == tok)
+                    continue;
+                if (lhs && lhs->valueType() && lhs->valueType()->isConst(vt->pointer))
+                    continue;
+            }
             if (const Token* ftok = getTokenArgumentFunction(tok, argn)) {
                 if (ftok->function()) {
                     const bool isCastArg = parent->isCast() && !ftok->function()->getOverloadedFunctions().empty(); // assume that cast changes the called function

lib/symboldatabase.cpp

@@ -2296,7 +2296,7 @@ Variable& Variable::operator=(const Variable &var) &
     if (this == &var)
         return *this;
 
-    ValueType* vt = nullptr;
+    const ValueType* vt = nullptr;
     if (var.mValueType)
         vt = new ValueType(*var.mValueType);
 
@@ -2462,7 +2462,7 @@ void Variable::setValueType(const ValueType &valueType)
         if (declType && !declType->next()->valueType())
             return;
     }
-    auto* vt = new ValueType(valueType);
+    const auto* vt = new ValueType(valueType);
     delete mValueType;
     mValueType = vt;
     if ((mValueType->pointer > 0) && (!isArray() || Token::Match(mNameToken->previous(), "( * %name% )")))

lib/tokenize.cpp

@@ -1243,7 +1243,7 @@ void Tokenizer::simplifyTypedefCpp()
         bool refToArray = false;
         bool ptrMember = false;
         bool typeOf = false;
-        Token *namespaceStart = nullptr;
+        const Token *namespaceStart = nullptr;
         Token *namespaceEnd = nullptr;
 
         // check for invalid input
@@ -3025,7 +3025,7 @@ bool Tokenizer::simplifyUsing()
         ScopeInfo3 scopeInfo1;
         ScopeInfo3 *currentScope1 = &scopeInfo1;
         Token *startToken = list.front();
-        Token *endToken = nullptr;
+        const Token *endToken = nullptr;
         bool inMemberFunc = false;
         const ScopeInfo3 * memberFuncScope = nullptr;
         const Token * memberFuncEnd = nullptr;
@@ -3039,7 +3039,7 @@ bool Tokenizer::simplifyUsing()
             if (!currentScope1)
                 return substitute; // something bad happened
             startToken = usingEnd->next();
-            endToken = const_cast<Token*>(currentScope->bodyEnd->next());
+            endToken = currentScope->bodyEnd->next();
             if (currentScope->type == ScopeInfo3::MemberFunction) {
                 const ScopeInfo3 * temp = currentScope->findScope(currentScope->fullName);
                 if (temp) {

test/testother.cpp

@@ -4497,6 +4497,16 @@ class TestOther : public TestFixture {
         ASSERT_EQUALS("[test.cpp:2:18]: (style) Parameter 's' can be declared as pointer to const [constParameterPointer]\n"
                       "[test.cpp:5:18]: (style) Parameter 's' can be declared as pointer to const [constParameterPointer]\n",
                       errout_str());
+
+        check("struct T;\n"
+              "void use(const T*);\n"
+              "void f(T* tok0) {\n"
+              "    T *tok1 = tok0;\n"
+              "    const T *tok2 = tok1;\n"
+              "    use(tok2);\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:4:8]: (style) Variable 'tok1' can be declared as pointer to const [constVariablePointer]\n",
+                      errout_str());
     }
 
     void constArray() {