[GCC] warning: ‘%lg’ directive output may be truncated

[AaronNGray]

I think is an issue with GCC's buffer overflow analysis accuracy.

This was reported in GCC v12.4 we are running v13.3.0.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114374

https://github.com/AaronNGray/pdfalto/actions/runs/13463238846/job/37623204502#step:9:450

/home/runner/work/pdfalto/pdfalto/src/AnnotsXrce.cc:444:59: warning: ‘%lg’ directive output may be truncated writing between 1 and 13 bytes into a region of size 8 [-Wformat-truncation=]
450 444 | snprintf(temp, sizeof(temp), "%lg", x);
451 | ^~~
452/home/runner/work/pdfalto/pdfalto/src/AnnotsXrce.cc:444:58: note: assuming directive output of 12 bytes
453 444 | snprintf(temp, sizeof(temp), "%lg", x);
454 | ^~~~~

snprintf(temp, sizeof(temp), "%lg", x);

https://github.com/AaronNGray/pdfalto/blob/buffer-overflows/src/AnnotsXrce.cc#L444

char *temp = (char *) malloc(16 * sizeof(char));

https://github.com/AaronNGray/pdfalto/blob/buffer-overflows/src/AnnotsXrce.cc#L419

It might be an idea to apply -Wformat-truncation just on GCC builds.