http://llvm.org/bugs/show_bug.cgi?id=11858
Bug #: 11858
Summary: clang should not default to -fno-math-errno
Product: clang
Version: 3.0
Platform: PC
OS/Version: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Driver
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
Classification: Unclassified
If I compile with optimisation, clang turns on -fno-math-errno. This is bad
because it breaks valid programs. There's a test case below. If I compile with
"clang -O" and run it, I get "result -nan, errno 0", which is wrong because
errno should be EDOM. I'm using the 3.0rc3 release on Linux/x86_64.
This behaviour was added under PR5971 but without much rationale.
Also see the brief thread at
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2011-November/018644.html
#include <errno.h>
#include <math.h>
#include <stdio.h>
int main(int argc, const char *argv[])
{
double d;
errno = 0;
d = sqrt(argc - 5);
printf("result %g, errno %d\n", d, errno);
return 0;
}
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