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Do not use __builtin_types_compatible_p in C++ mode (bug 21930)

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The logic to define isinf for float128 depends on the availability of
__builtin_types_compatible_p, which is only available in C mode,
however, the conditionals do not check for C or C++ mode.  This lead to
an error in libstdc++ configure, as reported by bug 21930.

This patch adds a conditional for C mode in the definition of isinf for
float128.  No definition is provided in C++ mode, since libstdc++
headers undefine isinf.

Tested for powerpc64le (glibc test suite and libstdc++-v3 configure).

	[BZ #21930]
	* math/math.h (isinf): Check if in C or C++ mode before using
	__builtin_types_compatible_p, since this is a C mode feature.
This commit is contained in:
Gabriel F. T. Gomes 2017-08-11 14:29:06 -03:00
parent c647fb885c
commit 47a67213a9
2 changed files with 12 additions and 2 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2017-08-18 Gabriel F. T. Gomes <gftg@linux.vnet.ibm.com>
[BZ #21930]
* math/math.h (isinf): Check if in C or C++ mode before using
__builtin_types_compatible_p, since this is a C mode feature.
2017-08-18 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/generic/not-cancel.h (write_not_cancel): Remove macro.

8
math/math.h
View file

@ -442,8 +442,12 @@ enum
/* Return nonzero value if X is positive or negative infinity. */
# if __HAVE_DISTINCT_FLOAT128 && !__GNUC_PREREQ (7,0) \
&& !defined __SUPPORT_SNAN__
/* __builtin_isinf_sign is broken for float128 only before GCC 7.0. */
&& !defined __SUPPORT_SNAN__ && !defined __cplusplus
/* Since __builtin_isinf_sign is broken for float128 before GCC 7.0,
use the helper function, __isinff128, with older compilers. This is
only provided for C mode, because in C++ mode, GCC has no support
for __builtin_types_compatible_p (and when in C++ mode, this macro is
not used anyway, because libstdc++ headers undefine it). */
# define isinf(x) \
(__builtin_types_compatible_p (__typeof (x), _Float128) \
? __isinff128 (x) : __builtin_isinf_sign (x))