False positive of 'knownConditionTrueFalse' when using a doublepointer in some cases

[ramonunch]

The original code where I got this problem was when using the Win32 FormatMessage() function that can allocate a string via a double pointer that has to be casted to a LPTSTR.
I tried first with cppcheck 2.10, then I build the latest 2.11 from source to test again. I am working on 32 bit windows.

I was able to reproduce this problem with a very short C code.

#include <stdio.h>

void MallocAndFillBuf(uintptr_t buf);

void funk()
{
    char *buf=NULL;

    MallocAndFillBuf((uintptr_t)&buf); // buf may be modified here!

    if (buf != NULL) // cppcheck says: "style: Condition 'buf!=NULL' is always false [knownConditionTrueFalse]"
        puts(buf);
}

The issue here is that I have to cast the '&buf' to uintptr_t if you change MallocAndFillBuf() to take a pointer type then no problems occur eg replace uintptr_t by void*.

I agree that this is very bad code but when using the Win32 API you often have this kind of code because of some callbacks and generic functions that take a LPARAM which is just an uintptr_t in disguise, so it would be nice if it did not cause problems.

My reasoning is that:
if you call f(&x), then whatever is the type that f() takes it might modify x because it has its address, this might not be true if the pointer is truncated in the conversion but it should not happen on working code.

Maybe I am missing something?

I would like to hive a huge thanks to everyone involved in the development of cppcheck, it really helped me locate some bugs in my code This project is amazing.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/11816