This part of the tests does pass on glibc on x86_64 and on MSVC,
but fails on macOS (for some functions) and on glibc on aarch64
(for one function).
This is a somewhat overly pedantic test, but is useful for checking
the NAN preservation behaviour when modifying implementations.
Also print the sign bit explicitly - not all printf implementations
distinguish between NAN and -NAN when printed.
When some of the parameters to standard C functions are known
constants, the compiler can optimize out the call to the actual
function.
When built with fortification enabled, the compiler previously
didn't actually end up calling the __<func>_chk functions in
most cases, as it could optimize out much of the calls. Now all
tested function calls should end up emitted as intended, making
this actually do functional testing of the __<func>_chk function
implementations.
The literal NAN in MSVC is a negative NAN, while it is a positive one
in other environments. (strtod("NAN", NULL) did return a positive NAN
though.) In most tests where we test that NANs are preserved, the exact
sign doesn't matter much as long as it matches, but for some tests, it
does matter. Change to using variables with known representation
in the tests where it matters.
Also add a LL suffix to make a tricky constant more correct.
In MSVC, the variable initialization
long long i = -2147483648;
actually sets the variable to the positive value 2147483648 (both
in MSVC 2019 and 2022).
The macros F() and L() etc were meant for providing constants for
the tests, without the compiler seeing them as constants, to
avoid optimizing out the entire functions that are to be tested.
However in practice, the compiler is also able to optimize out
e.g. a call to strtol("42", NULL, 0), so this didn't have the
intended effect.
Instead make the macros wrap through a no-op function, but which
is indirected via a global function pointer. The compiler can't
reason about global variables keeping their values (they could be
modified by e.g. a constructor in a different object file, before
running the main function). This avoids needing to pass all values
through strtod/strtol etc.
Change some constants like 123456789012345, which are seen by
the compiler as integer constants (which aren't exactly representable
in floating point form) into 123456789012345.0, which the compiler
won't complain about being inexact.
These are functions that, when built with "-D_FORTIFY_SOURCE=2 -O2",
can end up calling the corresponding __<func>_chk functions - thus,
this can be used for testing those functions.
Martin Storsjö