Fix -Wfloat-conversion C warnings on mingw in clamp_double_to_int64.

We just have to suppress these warnings: Mingw's math.h uses gcc's
__builtin_choose_expr() facility to declare isnan, isfinite, and
signbit.  But as implemented in at least some versions of gcc,
__builtin_choose_expr() can generate type warnings even from
branches that are not taken.

Fixes bug 22801; bugfix on 0.2.8.1-alpha.
This commit is contained in:
Nick Mathewson 2017-07-03 10:59:31 -04:00
parent 3483f7c003
commit 5361032219
2 changed files with 17 additions and 0 deletions

5
changes/bug22801 Normal file
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@ -0,0 +1,5 @@
o Minor bugfixes (compilation):
- When building with certain versions the mingw C header files, avoid
float-conversion warnings when calling the C functions isfinite(),
isnan(), and signbit(). Fixes bug 22801; bugfix on 0.2.8.1-alpha.

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@ -5537,6 +5537,15 @@ clamp_double_to_int64(double number)
{
int exp;
#if defined(__MINGW32__) || defined(__MINGW64__)
/*
Mingw's math.h uses gcc's __builtin_choose_expr() facility to declare
isnan, isfinite, and signbit. But as implemented in at least some
versions of gcc, __builtin_choose_expr() can generate type warnings
even from branches that are not taken. So, suppress those warnings.
*/
DISABLE_GCC_WARNING(float-conversion)
#endif
/* NaN is a special case that can't be used with the logic below. */
if (isnan(number)) {
return 0;
@ -5562,5 +5571,8 @@ clamp_double_to_int64(double number)
/* Handle infinities and finite numbers with magnitude >= 2^63. */
return signbit(number) ? INT64_MIN : INT64_MAX;
#if defined(__MINGW32__) || defined(__MINGW64__)
ENABLE_GCC_WARNING(float-conversion)
#endif
}