Fix #13093 FP incorrectStringBooleanError for nullptr check in macro (#6793)

Author: chrchr-github

lib/checkstring.cpp

@@ -254,8 +254,11 @@ void CheckString::strPlusCharError(const Token *tok)
 static bool isMacroUsage(const Token* tok)
 {
     if (const Token* parent = tok->astParent()) {
-        while (parent && (parent->isCast() || parent->str() == "&&"))
+        while (parent && (parent->isCast() || parent->str() == "&&")) {
+            if (parent->isExpandedMacro())
+                return true;
             parent = parent->astParent();
+        }
         if (!parent)
             return false;
         if (parent->isExpandedMacro())

test/teststring.cpp

@@ -808,6 +808,12 @@ class TestString : public TestFixture {
               "    MACRO(false && \"abc\");\n"
               "}\n");
         ASSERT_EQUALS("", errout_str());
+
+        check("#define strequ(s1,s2) ((void *)s1 && (void *)s2 && strcmp(s1, s2) == 0)\n" // #13093
+              "void f(const char* p) {\n"
+              "    if (strequ(p, \"ALL\")) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void deadStrcmp() {