Fix #12618 FN variableScope with member or array access (#6301)

Author: chrchr-github

lib/checkother.cpp

@@ -911,14 +911,20 @@ static bool isSimpleExpr(const Token* tok, const Variable* var, const Settings*
         return true;
     bool needsCheck = tok->varId() > 0;
     if (!needsCheck) {
+        if (tok->isArithmeticalOp())
+            return isSimpleExpr(tok->astOperand1(), var, settings) && (!tok->astOperand2() || isSimpleExpr(tok->astOperand2(), var, settings));
         const Token* ftok = tok->previous();
         if (Token::Match(ftok, "%name% (") &&
             ((ftok->function() && ftok->function()->isConst()) || settings->library.isFunctionConst(ftok->str(), /*pure*/ true)))
             needsCheck = true;
-        if (tok->isArithmeticalOp() &&
-            (!tok->astOperand1() || isSimpleExpr(tok->astOperand1(), var, settings)) &&
-            (!tok->astOperand2() || isSimpleExpr(tok->astOperand2(), var, settings)))
-            return true;
+        else if (tok->str() == "[") {
+            needsCheck = tok->astOperand1() && tok->astOperand1()->varId() > 0;
+            tok = tok->astOperand1();
+        }
+        else if (isLeafDot(tok->astOperand2())) {
+            needsCheck = tok->astOperand2()->varId() > 0;
+            tok = tok->astOperand2();
+        }
     }
     return (needsCheck && !findExpressionChanged(tok, tok->astParent(), var->scope()->bodyEnd, settings));
 }

lib/valueflow.cpp

@@ -8442,9 +8442,8 @@ bool ValueFlow::isContainerSizeChanged(const Token* tok, int indirect, const Set
         return true;
     if (astIsLHS(tok) && Token::Match(tok->astParent(), "%assign%|<<"))
         return true;
-    const Library::Container* container = tok->valueType()->container;
     if (astIsLHS(tok) && Token::simpleMatch(tok->astParent(), "["))
-        return container->stdAssociativeLike;
+        return tok->valueType()->container->stdAssociativeLike;
     const Library::Container::Action action = astContainerAction(tok);
     switch (action) {
     case Library::Container::Action::RESIZE:

test/testother.cpp

@@ -1712,7 +1712,7 @@ class TestOther : public TestFixture {
     }
 
     void varScope40() {
-        checkP("#define NUM (-999.9)\n"
+        checkP("#define NUM (-999.9)\n" // #8862
                "double f(int i) {\n"
                "    double a = NUM;\n"
                "    double b = -NUM;\n"
@@ -1732,6 +1732,19 @@ class TestOther : public TestFixture {
                       "[test.cpp:4]: (style) The scope of the variable 'b' can be reduced.\n"
                       "[test.cpp:5]: (style) The scope of the variable 'c' can be reduced.\n",
                       errout_str());
+
+        check("struct S { int a; };\n" // #12618
+              "int f(const S* s, int i) {\n"
+              "    int x = s->a;\n"
+              "    const int b[] = { 1, 2, 3 };\n"
+              "    int y = b[1];\n"
+              "    if (i)\n"
+              "        return x + y;\n"
+              "    return 0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (style) The scope of the variable 'x' can be reduced.\n"
+                      "[test.cpp:5]: (style) The scope of the variable 'y' can be reduced.\n",
+                      errout_str());
     }
 
 #define checkOldStylePointerCast(code) checkOldStylePointerCast_(code, __FILE__, __LINE__)