Created attachment 15196 [details]
test case foo.c

On Linux/alpha, the function fesetexceptflag() clears some exception flags that are outside the EXCEPTS argument. This violates ISO C 23 § 7.6.4.5, which says:
  "The fesetexceptflag function attempts to set the floating-point status flags indicated by the argument excepts to the states stored in the object pointed to by flagp."

How to reproduce:
Compile and run the attached program.
$ gcc -Wall foo.c -lm
$ ./a.out

Expected: It terminates with exit code 0.
Actual:
a.out: foo.c:58: main: Assertion `fetestexcept (FE_DIVBYZERO) == FE_DIVBYZERO' failed.
Aborted

When you compare the program's lines 49 and 58, you see that the invocation
  fesetexceptflag (&saved_flags_2, FE_OVERFLOW)
not only modified the FE_OVERFLOW flag bit, but also cleared the FE_DIVBYZERO flag bit.