Issue
While answering a question here, I made the following example:
#include <stdio.h>
#include <math.h>
int main (void)
{
float_t a = -248.75;
printf("%f\n", a);
unsigned char* ptr = (unsigned char*)&a;
for(size_t i=0; i<sizeof(a); i++)
{
printf("%.2X ", ptr[i]);
}
}
On gcc before version 13 as well as all versions of clang, this gives the expected output (x86 little endian):
-248.750000
00 C0 78 C3
However, when compiling with gcc 13.1, I get nonsense output:
-248.750000
00 00 00 00
Further examination shows that the culprit is the option -std=c2x
. If I remove it, the program behaves as expected.
Compiler options used: -std=c2x -pedantic-errors -Wall -Wextra -O3 -lm
. https://godbolt.org/z/4qbo74eEW
Is this a known bug in gcc?
Solution
This is now filed as a GCC bug, cf. https://gcc.gnu.org/PR111884
v11 and v12 seem to work for me.
Edit: This bug is fixed now in v13.3+
Answered By - emacs drives me nuts Answer Checked By - Cary Denson (WPSolving Admin)