Implement #7597 - valueflow: global constant (#1802)

* Implement const global value flow

* Tabs to spaces

lib/valueflow.cpp

@@ -1458,6 +1458,39 @@ static void valueFlowOppositeCondition(SymbolDatabase *symboldatabase, const Set
     }
 }
 
+static void valueFlowGlobalConstVar(TokenList* tokenList, const Settings *settings)
+{
+    // Get variable values...
+    std::map<const Variable*, ValueFlow::Value> vars;
+    for (const Token* tok = tokenList->front(); tok; tok = tok->next()) {
+        if (!tok->variable())
+            continue;
+        // Initialization...
+        if (tok == tok->variable()->nameToken() &&
+            !tok->variable()->isStatic() &&
+            tok->variable()->isConst() &&
+            tok->valueType() &&
+            tok->valueType()->isIntegral() &&
+            tok->valueType()->pointer == 0 &&
+            tok->valueType()->constness == 1 &&
+            Token::Match(tok, "%name% =") &&
+            tok->next()->astOperand2() &&
+            tok->next()->astOperand2()->hasKnownIntValue()) {
+            vars[tok->variable()] = tok->next()->astOperand2()->values().front();
+        }
+    }
+
+    // Set values..
+    for (Token* tok = tokenList->front(); tok; tok = tok->next()) {
+        if (!tok->variable())
+            continue;
+        std::map<const Variable*, ValueFlow::Value>::const_iterator var = vars.find(tok->variable());
+        if (var == vars.end())
+            continue;
+        setTokenValue(tok, var->second, settings);
+    }
+}
+
 static void valueFlowGlobalStaticVar(TokenList *tokenList, const Settings *settings)
 {
     // Get variable values...
@@ -5241,6 +5274,7 @@ void ValueFlow::setValues(TokenList *tokenlist, SymbolDatabase* symboldatabase,
     valueFlowNumber(tokenlist);
     valueFlowString(tokenlist);
     valueFlowArray(tokenlist);
+    valueFlowGlobalConstVar(tokenlist, settings);
     valueFlowGlobalStaticVar(tokenlist, settings);
     valueFlowPointerAlias(tokenlist);
     valueFlowLifetime(tokenlist, symboldatabase, errorLogger, settings);

test/testvalueflow.cpp

@@ -103,6 +103,8 @@ private:
 
         TEST_CASE(valueFlowGlobalVar);
 
+        TEST_CASE(valueFlowGlobalConstVar);
+
         TEST_CASE(valueFlowGlobalStaticVar);
 
         TEST_CASE(valueFlowInlineAssembly);
@@ -3165,6 +3167,16 @@ private:
         ASSERT_EQUALS(false, testValueOfX(code, 5U, 42));
     }
 
+    void valueFlowGlobalConstVar() {
+        const char* code;
+
+        code = "const int x = 321;\n"
+               "void f() {\n"
+               "  a = x;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 3U, 321));
+    }
+
     void valueFlowGlobalStaticVar() {
         const char *code;