[COMMITTED 2.31] Fix build with GCC 10 when long double = double.

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

[-- Attachment #1: Type: text/plain, Size: 412 bytes --]

backported this patch so we can build the 2.31 branch with
gcc-10 on arm-* targets.

IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

[-- Attachment #2: 0001-Fix-build-with-GCC-10-when-long-double-double.patch --]
[-- Type: text/x-diff, Size: 7142 bytes --]

From de371d1581f379ada10163d9172a8fde676d13b4 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Tue, 17 Mar 2020 22:57:42 +0000
Subject: [PATCH] Fix build with GCC 10 when long double = double.

On platforms where long double has the same ABI as double, glibc
defines long double functions as aliases for the corresponding double
functions.  The declarations of those functions in <math.h> are
disabled to avoid problems with aliases having incompatible types, but
GCC 10 now gives errors for incompatible types when the long double
function is known to GCC as a built-in function, not just when there
is an incompatible header declaration.

This patch fixes those errors by using appropriate
-fno-builtin-<function> options to compile the double functions.  The
list of CFLAGS-* settings is an appropriately adapted version of that
in sysdeps/ieee754/ldbl-opt/Makefile used there for building nldbl-*.c
files; in particular, the options are used even if GCC does not
currently have a built-in function of a given function, so that adding
such a built-in function in future will not break the glibc build.
Thus, various of the CFLAGS-* settings are only for future-proofing
and may not currently be needed (and it's possible some could be
irrelevant for other reasons).

Tested with build-many-glibcs.py for arm-linux-gnueabi (compilers and
glibcs builds), where it fixes the build that previously failed.

(cherry picked from commit 49348beafe9ba150c9bd48595b3f372299bddbb0)
---
 math/Makefile | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/math/Makefile b/math/Makefile
index 5985b6744b..3496af4040 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -644,6 +644,128 @@ ifneq ($(long-double-fcts),yes)
 # We won't compile the `long double' code at all.  Tell the `double' code
 # to define aliases for the `FUNCl' names.
 math-CPPFLAGS += -DNO_LONG_DOUBLE
+# GCC 10 diagnoses aliases with types conflicting with built-in
+# functions.
+CFLAGS-w_acos.c += -fno-builtin-acosl
+CFLAGS-w_acosh.c += -fno-builtin-acoshl
+CFLAGS-w_asin.c += -fno-builtin-asinl
+CFLAGS-s_asinh.c += -fno-builtin-asinhl
+CFLAGS-s_atan.c += -fno-builtin-atanl
+CFLAGS-w_atan2.c += -fno-builtin-atan2l
+CFLAGS-w_atanh.c += -fno-builtin-atanhl
+CFLAGS-s_cabs.c += -fno-builtin-cabsl
+CFLAGS-s_cacos.c += -fno-builtin-cacosl
+CFLAGS-s_cacosh.c += -fno-builtin-cacoshl
+CFLAGS-s_canonicalize.c += -fno-builtin-canonicalizel
+CFLAGS-s_carg.c += -fno-builtin-cargl
+CFLAGS-s_casin.c += -fno-builtin-casinl
+CFLAGS-s_casinh.c += -fno-builtin-casinhl
+CFLAGS-s_catan.c += -fno-builtin-catanl
+CFLAGS-s_catanh.c += -fno-builtin-catanhl
+CFLAGS-s_cbrt.c += -fno-builtin-cbrtl
+CFLAGS-s_ccos.c += -fno-builtin-ccosl
+CFLAGS-s_ccosh.c += -fno-builtin-ccoshl
+CFLAGS-s_ceil.c += -fno-builtin-ceill
+CFLAGS-s_cexp.c += -fno-builtin-cexpl
+CFLAGS-s_cimag.c += -fno-builtin-cimagl
+CFLAGS-s_clog.c += -fno-builtin-clogl
+CFLAGS-s_clog10.c += -fno-builtin-clog10l
+CFLAGS-s_conj.c += -fno-builtin-conjl
+CFLAGS-s_copysign.c += -fno-builtin-copysignl
+CFLAGS-s_cos.c += -fno-builtin-cosl
+CFLAGS-w_cosh.c += -fno-builtin-coshl
+CFLAGS-s_cpow.c += -fno-builtin-cpowl
+CFLAGS-s_cproj.c += -fno-builtin-cprojl
+CFLAGS-s_creal.c += -fno-builtin-creall
+CFLAGS-s_csin.c += -fno-builtin-csinl
+CFLAGS-s_csinh.c += -fno-builtin-csinhl
+CFLAGS-s_csqrt.c += -fno-builtin-csqrtl
+CFLAGS-s_ctan.c += -fno-builtin-ctanl
+CFLAGS-s_ctanh.c += -fno-builtin-ctanhl
+CFLAGS-s_dadd.c += -fno-builtin-daddl
+CFLAGS-s_ddiv.c += -fno-builtin-ddivl
+CFLAGS-s_dmul.c += -fno-builtin-dmull
+CFLAGS-s_dsub.c += -fno-builtin-dsubl
+CFLAGS-s_erf.c += -fno-builtin-erfl
+CFLAGS-s_erfc.c += -fno-builtin-erfcl
+CFLAGS-e_exp.c += -fno-builtin-expl
+CFLAGS-w_exp10.c += -fno-builtin-exp10l
+CFLAGS-e_exp2.c += -fno-builtin-exp2l
+CFLAGS-s_expm1.c += -fno-builtin-expm1l
+CFLAGS-s_fabs.c += -fno-builtin-fabsl
+CFLAGS-s_fadd.c += -fno-builtin-faddl
+CFLAGS-s_fdim.c += -fno-builtin-fdiml
+CFLAGS-s_fdiv.c += -fno-builtin-fdivl
+CFLAGS-s_finite.c += -fno-builtin-finitel
+CFLAGS-s_floor.c += -fno-builtin-floorl
+CFLAGS-s_fma.c += -fno-builtin-fmal
+CFLAGS-s_fmax.c += -fno-builtin-fmaxl
+CFLAGS-s_fmaxmag.c += -fno-builtin-fmaxmagl
+CFLAGS-s_fmin.c += -fno-builtin-fminl
+CFLAGS-s_fminmag.c += -fno-builtin-fminmagl
+CFLAGS-w_fmod.c += -fno-builtin-fmodl
+CFLAGS-s_fmul.c += -fno-builtin-fmull
+CFLAGS-s_frexp.c += -fno-builtin-frexpl
+CFLAGS-s_fromfp.c += -fno-builtin-fromfpl
+CFLAGS-s_fromfpx.c += -fno-builtin-fromfpxl
+CFLAGS-s_fsub.c += -fno-builtin-fsubl
+CFLAGS-s_gamma.c += -fno-builtin-gammal
+CFLAGS-s_getpayload.c += -fno-builtin-getpayloadl
+CFLAGS-w_hypot.c += -fno-builtin-hypotl
+CFLAGS-w_ilogb.c += -fno-builtin-ilogbl
+CFLAGS-s_isinf.c += -fno-builtin-isinfl
+CFLAGS-s_isnan.c += -fno-builtin-isnanl
+CFLAGS-w_j0.c += -fno-builtin-j0l
+CFLAGS-w_j1.c += -fno-builtin-j1l
+CFLAGS-w_jn.c += -fno-builtin-jnl
+CFLAGS-s_ldexp.c += -fno-builtin-ldexpl
+CFLAGS-w_lgamma.c += -fno-builtin-lgammal
+CFLAGS-w_lgamma_r.c += -fno-builtin-lgammal_r
+CFLAGS-w_llogb.c += -fno-builtin-llogbl
+CFLAGS-s_llrint.c += -fno-builtin-llrintl
+CFLAGS-s_llround.c += -fno-builtin-llroundl
+CFLAGS-e_log.c += -fno-builtin-logl
+CFLAGS-w_log10.c += -fno-builtin-log10l
+CFLAGS-w_log1p.c += -fno-builtin-log1pl
+CFLAGS-e_log2.c += -fno-builtin-log2l
+CFLAGS-s_logb.c += -fno-builtin-logbl
+CFLAGS-s_lrint.c += -fno-builtin-lrintl
+CFLAGS-s_lround.c += -fno-builtin-lroundl
+CFLAGS-s_modf.c += -fno-builtin-modfl
+CFLAGS-s_nan.c += -fno-builtin-nanl
+CFLAGS-s_nearbyint.c += -fno-builtin-nearbyintl
+CFLAGS-s_nextafter.c += -fno-builtin-nextafterl
+CFLAGS-s_nextdown.c += -fno-builtin-nextdownl
+CFLAGS-s_nexttoward.c += -fno-builtin-nexttoward -fno-builtin-nexttowardl
+CFLAGS-s_nexttowardf.c += -fno-builtin-nexttowardf
+CFLAGS-s_nextup.c += -fno-builtin-nextupl
+CFLAGS-e_pow.c += -fno-builtin-powl
+CFLAGS-w_remainder.c += -fno-builtin-remainderl -fno-builtin-dreml
+CFLAGS-s_remquo.c += -fno-builtin-remquol
+CFLAGS-s_rint.c += -fno-builtin-rintl
+CFLAGS-s_round.c += -fno-builtin-roundl
+CFLAGS-s_roundeven.c += -fno-builtin-roundevenl
+CFLAGS-w_scalb.c += -fno-builtin-scalbl
+CFLAGS-w_scalbln.c += -fno-builtin-scalblnl
+CFLAGS-s_scalbn.c += -fno-builtin-scalbnl
+CFLAGS-s_setpayload.c += -fno-builtin-setpayloadl
+CFLAGS-s_setpayloadsig.c += -fno-builtin-setpayloadsigl
+CFLAGS-s_significand.c += -fno-builtin-significandl
+CFLAGS-s_sin.c += -fno-builtin-sinl
+CFLAGS-s_sincos.c += -fno-builtin-sincosl
+CFLAGS-w_sinh.c += -fno-builtin-sinhl
+CFLAGS-w_sqrt.c += -fno-builtin-sqrtl
+CFLAGS-s_tan.c += -fno-builtin-tanl
+CFLAGS-s_tanh.c += -fno-builtin-tanhl
+CFLAGS-w_tgamma.c += -fno-builtin-tgammal
+CFLAGS-s_totalorder.c += -fno-builtin-totalorderl
+CFLAGS-s_totalordermag.c += -fno-builtin-totalordermagl
+CFLAGS-s_trunc.c += -fno-builtin-truncl
+CFLAGS-s_ufromfp.c += -fno-builtin-ufromfpl
+CFLAGS-s_ufromfpx.c += -fno-builtin-ufromfpxl
+CFLAGS-s_y0.c += -fno-builtin-y0l
+CFLAGS-s_y1.c += -fno-builtin-y1l
+CFLAGS-s_yn.c += -fno-builtin-ynl
 endif
 
 # These files quiet sNaNs in a way that is optimized away without
-- 
2.17.1