[clang] [-Wunsafe-buffer-usage] Warning Libc functions (PR #101583)

[Mikael Holmén via cfe-commits]

mikaelholmen wrote:

Btw a question about the new warning: So with -Wunsafe-buffer-usage-in-libc-call clang now warns on the following?
```
#include <stdio.h>

void foo(void) {
  char q[10];
  snprintf(q, 10, "%s", "hello");
}
```
It says
```
foo.c:5:3: warning: function 'snprintf' is unsafe [-Wunsafe-buffer-usage-in-libc-call]
    5 |   snprintf(q, 10, "%s", "hello");
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:5:12: note:  buffer pointer and size may not match
    5 |   snprintf(q, 10, "%s", "hello");
      |            ^
1 warning generated.
```
Is that as expected? If so, how should snprintf be used to avoid the warning?


https://github.com/llvm/llvm-project/pull/101583