Fix #12072 FN constStatement with enum (#5554)

Author: chrchr-github

lib/checkother.cpp

@@ -1892,7 +1892,7 @@ static bool isBracketAccess(const Token* tok)
 }
 
 static bool isConstant(const Token* tok) {
-    return Token::Match(tok, "%bool%|%num%|%str%|%char%|nullptr|NULL");
+    return tok && (tok->isEnumerator() || Token::Match(tok, "%bool%|%num%|%str%|%char%|nullptr|NULL"));
 }
 
 static bool isConstStatement(const Token *tok, bool cpp)
@@ -2072,6 +2072,8 @@ void CheckOther::constStatementError(const Token *tok, const std::string &type,
             typeStr = "character";
         else if (isNullOperand(valueTok))
             typeStr = "NULL";
+        else if (valueTok->isEnumerator())
+            typeStr = "enumerator";
         msg = "Redundant code: Found a statement that begins with " + typeStr + " constant.";
     }
     else if (!tok)

test/testincompletestatement.cpp

@@ -703,6 +703,13 @@ class TestIncompleteStatement : public TestFixture {
               "    auto g = [](decltype(a[0]) i) {};\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("enum E { E0 };\n"
+              "void f() {\n"
+              "    E0;\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:3]: (warning) Redundant code: Found a statement that begins with enumerator constant.\n",
+                      errout.str());
     }
 
     void vardecl() {