Fix #7091 FN variableScope for variables used in inner loop (#8245)

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

Author: chrchr-github

lib/checkother.cpp

@@ -1331,6 +1331,15 @@ static bool mayDependOn(const ValueType *other, const ValueType *original)
     return otherPtr > originalPtr;
 }
 
+static bool isOnlyUsedInCurrentScope(const Variable* var, const Token *tok, const Scope* scope)
+{
+    if (tok->scope() == scope)
+        return true;
+    if (tok->scope()->type == ScopeType::eSwitch)
+        return false;
+    return !Token::findmatch(tok->scope()->bodyEnd, "%varid%", scope->bodyEnd, var->declarationId());
+}
+
 bool CheckOther::checkInnerScope(const Token *tok, const Variable* var, bool& used) const
 {
     const Scope* scope = tok->next()->scope();
@@ -1370,7 +1379,8 @@ bool CheckOther::checkInnerScope(const Token *tok, const Variable* var, bool& us
         if (tok == forHeadEnd)
             forHeadEnd = nullptr;
 
-        if (loopVariable && noContinue && tok->scope() == scope && !forHeadEnd && scope->type != ScopeType::eSwitch && Token::Match(tok, "%varid% =", var->declarationId())) { // Assigned in outer scope.
+        if (loopVariable && noContinue && !forHeadEnd && scope->type != ScopeType::eSwitch && Token::Match(tok, "%varid% =", var->declarationId()) &&
+            isOnlyUsedInCurrentScope(var, tok, scope)) { // Assigned in outer scope.
             loopVariable = false;
             std::pair<const Token*, const Token*> range = tok->next()->findExpressionStartEndTokens();
             if (range.first)

test/testother.cpp

@@ -123,6 +123,7 @@ class TestOther : public TestFixture {
         TEST_CASE(varScope43);
         TEST_CASE(varScope44);
         TEST_CASE(varScope45);
+        TEST_CASE(varScope46);
 
         TEST_CASE(oldStylePointerCast);
         TEST_CASE(intToPointerCast);
@@ -1984,6 +1985,49 @@ class TestOther : public TestFixture {
         ASSERT_EQUALS("[test.cpp:2:16]: (style) The scope of the variable 'b' can be reduced. [variableScope]\n", errout_str());
     }
 
+    void varScope46() {
+        check("void f() {\n" // #7091
+              "    int y1;\n"
+              "    for (int i = 0; i < 3; ++i) {\n"
+              "        for(int j = 0; j < 3; ++j) {\n"
+              "                y1 = 2 * 1;\n"
+              "                y1 += 1;\n"
+              "        }\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2:9]: (style) The scope of the variable 'y1' can be reduced. [variableScope]\n",
+                      errout_str());
+
+        check("bool f() {\n"
+              "bool b = false;\n"
+              "do {\n"
+              "    switch (g()) {\n"
+              "        case 0:\n"
+              "            b = true;\n"
+              "            break;\n"
+              "        case 1:\n"
+              "            return b;\n"
+              "            break;\n"
+              "        default:\n"
+              "            break;\n"
+              "    }\n"
+              "}\n"
+              "while (true);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("void f() {\n"
+              "    int y1 = 0;\n"
+              "    for (int i = 0; i < 3; ++i) {\n"
+              "        for(int j = 0; j < 3; ++j) {\n"
+              "                y1 = y1 + 1;\n"
+              "                dostuff(y1);\n"
+              "        }\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+    }
+
 #define checkOldStylePointerCast(...) checkOldStylePointerCast_(__FILE__, __LINE__, __VA_ARGS__)
     template<size_t size>
     void checkOldStylePointerCast_(const char* file, int line, const char (&code)[size], Standards::cppstd_t std = Standards::CPPLatest) {