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List:       glibc-cvs
Subject:    [glibc] Do not declare fmax, fmin _FloatN, _FloatNx versions for C2X
From:       Joseph Myers via Glibc-cvs <glibc-cvs () sourceware ! org>
Date:       2021-09-29 18:20:51
Message-ID: 20210929182051.269613858406 () sourceware ! org
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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9bd9978639c2f75dbea5c25226264b1ac11fdf05

commit 9bd9978639c2f75dbea5c25226264b1ac11fdf05
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Sep 29 18:20:32 2021 +0000

    Do not declare fmax, fmin _FloatN, _FloatNx versions for C2X
    
    At the last WG14 meeting,
    <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2711.htm> was
    accepted, which places more emphasis on the new fmaximum / fminimum
    functions and less on the old fmax / fmin functions.  Some of the
    changes are to examples, notes or otherwise don't require
    implementation changes.  However, the changes include removing the
    _FloatN / _FloatNx versions of the fmax and fmin functions that came
    from TS 18661-3.
    
    Thus, those function versions should only be declared under similar
    conditions to the _FloatN / _FloatNx versions of fmaxmag and fminmag:
    for _GNU_SOURCE and pre-C2X use of __STDC_WANT_IEC_60559_TYPES_EXT__,
    but not for C2X without _GNU_SOURCE.
    
    In turn this requires a tgmath.h change so that the corresponding
    tgmath.h macros, for C2X with __STDC_WANT_IEC_60559_TYPES_EXT__ but
    without _GNU_SOURCE, don't try to use function variants that aren't
    declared.  (That issue doesn't arise for the tgmath.h macros for
    fmaxmag and fminmag, because those aren't defined at all in those
    circumstances unless __STDC_WANT_IEC_60559_BFP_EXT__ (from TS 18661-1
    and not specified at all by C2X) is also defined, and in that case the
    _FloatN / _FloatNx versions of fmaxmag and fminmag get declared - this
    is only ever an issue when it's possible for some functions
    corresponding to a type-generic-macro to be declared, and for _FloatN
    / _FloatNx functions in general to be declared, but without the
    _FloatN / _FloatNx functions corresponding to that particular macro
    being declared.)
    
    Tested for x86_64.

Diff:
---
 math/bits/mathcalls.h |  2 ++
 math/tgmath.h         | 12 ++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/math/bits/mathcalls.h b/math/bits/mathcalls.h
index ee0c6d7219..da4cf4e10c 100644
--- a/math/bits/mathcalls.h
+++ b/math/bits/mathcalls.h
@@ -328,11 +328,13 @@ __MATHDECL (long long int,llround,, (_Mdouble_ __x));
 /* Return positive difference between X and Y.  */
 __MATHCALL (fdim,, (_Mdouble_ __x, _Mdouble_ __y));
 
+# if !__MATH_DECLARING_FLOATN || defined __USE_GNU || !__GLIBC_USE (ISOC2X)
 /* Return maximum numeric value from X and Y.  */
 __MATHCALLX (fmax,, (_Mdouble_ __x, _Mdouble_ __y), (__const__));
 
 /* Return minimum numeric value from X and Y.  */
 __MATHCALLX (fmin,, (_Mdouble_ __x, _Mdouble_ __y), (__const__));
+# endif
 
 /* Multiply-add function computed as a ternary operation.  */
 __MATHCALL (fma,, (_Mdouble_ __x, _Mdouble_ __y, _Mdouble_ __z));
diff --git a/math/tgmath.h b/math/tgmath.h
index 3d7b0998df..e8042833dd 100644
--- a/math/tgmath.h
+++ b/math/tgmath.h
@@ -892,12 +892,20 @@
 /* Return positive difference between X and Y.  */
 #define fdim(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fdim)
 
+#if __GLIBC_USE (ISOC2X) && !defined __USE_GNU
 /* Return maximum numeric value from X and Y.  */
-#define fmax(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fmax)
+# define fmax(Val1, Val2) __TGMATH_BINARY_REAL_STD_ONLY (Val1, Val2, fmax)
 
 /* Return minimum numeric value from X and Y.  */
-#define fmin(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fmin)
+# define fmin(Val1, Val2) __TGMATH_BINARY_REAL_STD_ONLY (Val1, Val2, fmin)
+#else
+/* Return maximum numeric value from X and Y.  */
+# define fmax(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fmax)
 
+/* Return minimum numeric value from X and Y.  */
+# define fmin(Val1, Val2) __TGMATH_BINARY_REAL_ONLY (Val1, Val2, fmin)
+#endif
+  
 
 /* Multiply-add function computed as a ternary operation.  */
 #define fma(Val1, Val2, Val3) \
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