[PATCH] libgfortran : Use the libtool macro to determine libm availability.

Iain Sandoe iain@sandoe.co.uk
Fri Aug 27 15:53:15 GMT 2021



> On 22 Aug 2021, at 09:44, Iain Sandoe <iain@sandoe.co.uk> wrote:
> 
> 
> 
>> On 21 Aug 2021, at 23:18, Eric Gallager <egall@gwmail.gwu.edu> wrote:
>> 
>> On Fri, Aug 20, 2021 at 3:53 AM Tobias Burnus <tobias@codesourcery.com> wrote:
>>> 
>>> On 20.08.21 09:34, Richard Biener via Fortran wrote:
>>> 
>>>> On Thu, Aug 19, 2021 at 10:10 PM Iain Sandoe <iain@sandoe.co.uk> wrote:
>>>>> libm is not needed on Darwin, and should not be added unconditionally
>>>>> even if that is (mostly) harmless since it is a symlink to libc.
>>>>> 
>>>>> tested on x86_64, i686-darwin, x86_64-linux,
>>>>> OK for master?
>>>> OK.
>>>> Richard.
>>> 
>>> Looks also good to me – but for completeness and as background, I also
>>> want to remark the following.
>>> 
>>> (At least as I understand it, I did not dig deeper.)
>>> 
>>>> --- a/libgfortran/configure.ac
>>>> +++ b/libgfortran/configure.ac
>>>> ...
>>>> +AC_CHECK_LIBM
>>> 
>>> This CHECK_LIBM has a hard-coded list of targets and for some (like
>>> Darwin) it simply does not set $LIBM.
>> 
>> I thought the proper macro to use was LT_LIB_M ?
> 
> you could well be right, libtool.m4 contains:
> 
> # Old name:
> AU_ALIAS([AC_CHECK_LIBM], [LT_LIB_M])
> 
> I guess the patch can be changed and then do another round of testing …
> … will add this to the TODO, and withdraw the current patch.

this is what I pushed after retesting (with the extras space removed too):

======
libgfortran: Use the libtool macro to determine libm
 availability.

We recently had a report of build failure against a Darwin branch on
the latest OS release.  This was because (temporarily) the symlink
from libm.dylib => libSystem.dylib had been removed/omitted.

libm is not needed on Darwin, and should not be added unconditionally
even if that is (mostly) harmless since it is a symlink to libc.

There could be cases where the addition was not completely harmless
because the presentation of the symlink would cause the symbols exposed
in libSystem to be considered ahead of ones presented in convenience
libraries.

libgfortran/ChangeLog:

	* Makefile.am: Use configured libm availability.
	* Makefile.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Use libtool macro to find libm availability.
	* libgfortran.spec.in: Use configured libm availability.
---
 libgfortran/Makefile.am         |   2 +-
 libgfortran/Makefile.in         |   3 +-
 libgfortran/configure           | 146 +++++++++++++++++++++++++++++++-
 libgfortran/configure.ac        |   1 +
 libgfortran/libgfortran.spec.in |   2 +-
 5 files changed, 149 insertions(+), 5 deletions(-)

diff --git a/libgfortran/Makefile.am b/libgfortran/Makefile.am
index 8d104321567..6fc4b465c6e 100644
--- a/libgfortran/Makefile.am
+++ b/libgfortran/Makefile.am
@@ -42,7 +42,7 @@ libgfortran_la_LINK = $(LINK) $(libgfortran_la_LDFLAGS)
 libgfortran_la_LDFLAGS = -version-info `grep -v '^\#' $(srcdir)/libtool-version` \
 	$(LTLDFLAGS) $(LIBQUADLIB) ../libbacktrace/libbacktrace.la \
 	$(HWCAP_LDFLAGS) \
-	-lm $(extra_ldflags_libgfortran) \
+	$(LIBM) $(extra_ldflags_libgfortran) \
 	$(version_arg) -Wc,-shared-libgcc
 libgfortran_la_DEPENDENCIES = $(version_dep) libgfortran.spec $(LIBQUADLIB_DEP)
  
 
diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
index 523eb24bca1..a77509801e6 100644
--- a/libgfortran/configure.ac
+++ b/libgfortran/configure.ac
@@ -260,6 +260,7 @@ AC_PROG_INSTALL
 #AC_MSG_NOTICE([====== Starting libtool configuration])
 AC_LIBTOOL_DLOPEN
 AM_PROG_LIBTOOL
+LT_LIB_M
 ACX_LT_HOST_FLAGS
 AC_SUBST(enable_shared)
 AC_SUBST(enable_static)
diff --git a/libgfortran/libgfortran.spec.in b/libgfortran/libgfortran.spec.in
index 95aa3f842a3..367d485c230 100644
--- a/libgfortran/libgfortran.spec.in
+++ b/libgfortran/libgfortran.spec.in
@@ -5,4 +5,4 @@
 #
 
 %rename lib liborig
-*lib: @LIBQUADSPEC@ -lm %(libgcc) %(liborig)
+*lib: @LIBQUADSPEC@ @LIBM@ %(libgcc) %(liborig)
-- 
2.24.3 (Apple Git-128)



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