Fix #14889 FP constStatement with GNU statement expression (#8698)

Author: chrchr-github

lib/checkother.cpp

@@ -2408,7 +2408,7 @@ void CheckOtherImpl::checkIncompleteStatement()
             !(tok->str() == "," && tok->astParent() && tok->astParent()->isAssignmentOp()))
             continue;
         // Skip statement expressions
-        if (Token::simpleMatch(rtok, "; } )"))
+        if (Token::simpleMatch(rtok, "; } )") || Token::simpleMatch(tok->next(), "; } )"))
             continue;
         if (!isConstStatement(tok, mSettings.library, false))
             continue;

test/testincompletestatement.cpp

@@ -758,6 +758,11 @@ class TestIncompleteStatement : public TestFixture {
               "}\n");
         ASSERT_EQUALS("[test.cpp:4:6]: (warning) Redundant code: Found unused array access. [constStatement]\n",
                       errout_str());
+
+        check("int f(int i) {\n" // #14889
+              "    return i ? 8 : ({ int x = 2; x; });\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void vardecl() {