Fix #13177 FN: constStatement (sizeof(int)) (#7712)

Author: chrchr-github

lib/checkother.cpp

@@ -2164,7 +2164,7 @@ static bool isConstStatement(const Token *tok, const Library& library, bool isNe
         return isConstStatement(tok->astOperand1(), library) && isConstStatement(tok->astOperand2(), library);
     if (Token::Match(tok, "!|~|%cop%") && (tok->astOperand1() || tok->astOperand2()))
         return true;
-    if (Token::simpleMatch(tok->previous(), "sizeof ("))
+    if (Token::Match(tok->previous(), "sizeof|alignof|noexcept|typeid (") && tok->previous()->isKeyword())
         return true;
     if (isCPPCast(tok)) {
         if (Token::simpleMatch(tok->astOperand1(), "dynamic_cast") && Token::simpleMatch(tok->astOperand1()->linkAt(1)->previous(), "& >"))
@@ -2299,6 +2299,7 @@ void CheckOther::checkIncompleteStatement()
         if (!Token::simpleMatch(tok->astParent(), ";") && !Token::simpleMatch(rtok, ";") &&
             !Token::Match(tok->previous(), ";|}|{ %any% ;") &&
             !(tok->isCpp() && tok->isCast() && !tok->astParent()) &&
+            !(!tok->astParent() && Token::Match(tok->previous(), "%name% (") && tok->previous()->isKeyword()) &&
             !Token::simpleMatch(tok->tokAt(-2), "for (") &&
             !Token::Match(tok->tokAt(-1), "%var% [") &&
             !(tok->str() == "," && tok->astParent() && tok->astParent()->isAssignmentOp()))
@@ -2362,6 +2363,8 @@ void CheckOther::constStatementError(const Token *tok, const std::string &type,
         msg = "Redundant code: Found unused lambda.";
     else if (Token::Match(tok, "%name%|::"))
         msg = "Redundant code: Found unused function.";
+    else if (Token::Match(tok->previous(), "%name% ("))
+        msg = "Redundant code: Found unused '" + tok->strAt(-1) + "' expression.";
     else if (mSettings->debugwarnings) {
         reportError(tok, Severity::debug, "debug", "constStatementError not handled.");
         return;

test/testincompletestatement.cpp

@@ -730,6 +730,19 @@ class TestIncompleteStatement : public TestFixture {
               "}\n");
         ASSERT_EQUALS("[test.cpp:3:5]: (warning) Redundant code: Found unused lambda. [constStatement]\n",
                       errout_str());
+
+        check("int main() {\n" // #13177
+              "    sizeof(int);\n"
+              "    alignof(long double*);\n"
+              "    noexcept(int());\n"
+              "    typeid(int);\n"
+              "    return(0);\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2:11]: (warning) Redundant code: Found unused 'sizeof' expression. [constStatement]\n"
+                      "[test.cpp:3:12]: (warning) Redundant code: Found unused 'alignof' expression. [constStatement]\n"
+                      "[test.cpp:4:13]: (warning) Redundant code: Found unused 'noexcept' expression. [constStatement]\n"
+                      "[test.cpp:5:11]: (warning) Redundant code: Found unused 'typeid' expression. [constStatement]\n",
+                      errout_str());
     }
 
     void vardecl() {