Spurious nullPointerRedundantCheck

[James Bray]

Hi,

I have the following code:

void func( )
{
   char *text = strdup("test")
   if (!text) goto END;

   if (strcmp(text, "test"))
       printf("Different\n");

   if (text) free(text);

   return;

END:
}

When running using 2.18 or the latest code from 17-Oct-25, I get the following spurious warnings:

test.c:6:15: warning: Either the condition 'text' is redundant or there is possible null pointer dereference: text. [nullPointerRedundantCheck]
if (strcmp(text, "test"))
^
test.c:9:8: note: Assuming that condition 'text' is not redundant
if (text) free(text);
^
test.c:6:15: note: Null pointer dereference
if (strcmp(text, "test"))

If I remove the final "if (text)" condition, it no longer generates the warnings. I would not expect that redundant condition to cause warnings in the strcmp call at the beginning.

This didn't occur in 2.17, and at the moment, I'm forced to suppress that particular check.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/14214
Maybe you can avoid the warning by adding --check-level=exhaustive to your command line.

[James Bray]

Hi, thanks for the suggestion. That does remove the error, but unfortunately a trivial change re-introduces it:

void func( )
{
   char *text = strdup("test")
   if (!text) goto END;

   if (strcmp(text, "test"))
       goto END;

   if (text) free(text);

   return;

END:
}

Replacing the "printf" with "goto END" in the strcmp conditional causes the nullPointerRedundantCheck to occur even with --check-level=exhaustive

For the moment I will simply disable this warning.