FwdAnalysis; Code cleanup, isNullOperand

lib/astutils.cpp

@@ -1080,25 +1080,18 @@ struct FwdAnalysis::Result FwdAnalysis::checkRecursive(const Token *expr, const
 
         if (Token::Match(tok, "return|throw")) {
             // TODO: Handle these better
-            switch (mWhat) {
-            case What::Reassign:
-                return Result(Result::Type::RETURN);
-            case What::UnusedValue:
-                // Is expr variable used in expression?
-            {
-                bool read = false;
-                visitAstNodes(tok->astOperand1(),
-                [&](const Token *tok2) {
-                    if (!local && Token::Match(tok2, "%name% ("))
-                        read = true;
-                    if (tok2->varId() && exprVarIds.find(tok2->varId()) != exprVarIds.end())
-                        read = true;
-                    return read ? ChildrenToVisit::done : ChildrenToVisit::op1_and_op2;
-                });
+            // Is expr variable used in expression?
+            bool read = false;
+            visitAstNodes(tok->astOperand1(),
+            [&](const Token *tok2) {
+                if (!local && Token::Match(tok2, "%name% ("))
+                    read = true;
+                if (tok2->varId() && exprVarIds.find(tok2->varId()) != exprVarIds.end())
+                    read = true;
+                return read ? ChildrenToVisit::done : ChildrenToVisit::op1_and_op2;
+            });
 
-                return Result(read ? Result::Type::READ : Result::Type::RETURN);
-            }
-            }
+            return Result(read ? Result::Type::READ : Result::Type::RETURN);
         }
 
         if (tok->str() == "}") {
@@ -1307,3 +1300,12 @@ bool FwdAnalysis::possiblyAliased(const Token *expr, const Token *startToken) co
     }
     return false;
 }
+
+bool FwdAnalysis::isNullOperand(const Token *expr)
+{
+    if (!expr)
+        return false;
+    if (Token::Match(expr, "( %name% %name%| * )") && Token::Match(expr->astOperand1(), "0|NULL|nullptr"))
+        return true;
+    return Token::Match(expr, "NULL|nullptr");
+}

lib/astutils.h

@@ -187,6 +187,8 @@ public:
     /** Is there some possible alias for given expression */
     bool possiblyAliased(const Token *expr, const Token *startToken) const;
 
+    static bool isNullOperand(const Token *expr);
+
 private:
     /** Result of forward analysis */
     struct Result {

lib/checkother.cpp

@@ -449,7 +449,7 @@ void CheckOther::checkRedundantAssignment()
                 }
 
                 // Do not warn about assignment with 0 / NULL
-                if (Token::Match(tok->astOperand2(), "0|NULL|nullptr"))
+                if (Token::simpleMatch(tok->astOperand2(), "0") || FwdAnalysis::isNullOperand(tok->astOperand2()))
                     continue;
 
                 if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isReference())

lib/checkunusedvar.cpp

@@ -1254,7 +1254,7 @@ void CheckUnusedVar::checkFunctionVariableUsage()
                     continue;
             }
             // Do not warn about assignment with NULL
-            if (tok->astOperand1() && tok->astOperand1()->valueType() && tok->astOperand1()->valueType()->pointer && Token::Match(tok->astOperand2(), "0|NULL|nullptr"))
+            if (FwdAnalysis::isNullOperand(tok->astOperand2()))
                 continue;
 
             if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isReference() && tok->astOperand1()->variable()->nameToken() != tok->astOperand1())

test/testunusedvar.cpp

@@ -4019,6 +4019,12 @@ private:
                               "    p = NULL;\n"
                               "}");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("void f(Foo *p) {\n"
+                              "    free(p);\n"
+                              "    p = (Foo *)NULL;\n"
+                              "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void localvarUnusedGoto() {