Re: [PATCH] totalorder, totalorderf, totalorderl: new modules

[Bruno Haible]

The gnulib CI failed today, with this error:

depbase=`echo c-vsnprintf.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
ccache gcc -DHAVE_CONFIG_H -DEXEEXT=\"\" -DEXEEXT=\"\" -DNO_XMALLOC 
-DEXEEXT=\"\" -I. -I..  -DGNULIB_STRICT_CHECKING=1  -fvisibility=hidden -g -O2 
-MT c-vsnprintf.o -MD -MP -MF $depbase.Tpo -c -o c-vsnprintf.o c-vsnprintf.c &&\
mv -f $depbase.Tpo $depbase.Po
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:196,
                 from ./sys/types.h:46,
                 from ./stdio.h:76,
                 from c-vasnprintf.h:32,
                 from c-vasnprintf.c:20:
./math.h:3288:1: error: conflicting types for 'totalorderf'
 _GL_FUNCDECL_SYS (totalorderf, int, (float const *, float const *));
 ^~~~~~~~~~~~~~~~
In file included from ./math.h:46,
                 from vasnprintf.c:107,
                 from c-vasnprintf.c:46:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:371:1: note: previous 
declaration of 'totalorderf' was here
 __MATHDECL_1 (int, totalorder,, (_Mdouble_ __x, _Mdouble_ __y))
 ^~~~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:196,
                 from ./sys/types.h:46,
                 from ./stdio.h:76,
                 from c-vasnprintf.h:32,
                 from c-vasnprintf.c:20:
./math.h:3311:1: error: conflicting types for 'totalorder'
 _GL_FUNCDECL_SYS (totalorder, int, (double const *, double const *));
 ^~~~~~~~~~~~~~~~
In file included from /usr/include/features.h:424,
                 from /usr/include/assert.h:35,
                 from ./assert.h:26,
                 from ../config.h:8358,
                 from c-vasnprintf.c:17:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:371:1: note: previous 
declaration of 'totalorder' was here
 __MATHDECL_1 (int, totalorder,, (_Mdouble_ __x, _Mdouble_ __y))
 ^~~~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:196,
                 from ./sys/types.h:46,
                 from ./stdio.h:76,
                 from c-vasnprintf.h:32,
                 from c-vasnprintf.c:20:
./math.h:3338:1: error: conflicting types for 'totalorderl'
 _GL_FUNCDECL_SYS (totalorderl, int,
 ^~~~~~~~~~~~~~~~
In file included from ./math.h:46,
                 from vasnprintf.c:107,
                 from c-vasnprintf.c:46:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:371:1: note: previous 
declaration of 'totalorderl' was here
 __MATHDECL_1 (int, totalorder,, (_Mdouble_ __x, _Mdouble_ __y))
 ^~~~~~~~~~~~
make[4]: *** [Makefile:11173: c-vasnprintf.o] Error 1

Our documentation says
"This function has a different signature on some platforms:
 glibc 2.30."

The gnulib CI happens to be running on a Debian 10 system, that is, with
glibc 2.28. And indeed, I reproduce the compilation error on Debian 10
and CentOS 8; both have glibc 2.28.

The cause is the configuration code in m4/totalorder.m4. It attempts
to decide based on the *_no_libm and *_in_libm variables whether to
set REPLACE_TOTALORDER=1 or not. But that is not possible; it requires
a test of the declaration in <math.h>, not a link test, to determine this.

This patch fixes it.


2023-10-07  Bruno Haible  <bruno@clisp.org>

        totalorder*: Fix compilation error on glibc 2.25..2.30.
        * m4/totalorder.m4 (gl_FUNC_TOTALORDERF): Test whether <math.h> has an
        incompatible declaration of totalorderf, and set REPLACE_TOTALORDERF
        to 1 if so.
        (gl_FUNC_TOTALORDER): Test whether <math.h> has an incompatible
        declaration of totalorder, and set REPLACE_TOTALORDER to 1 if so.
        (gl_FUNC_TOTALORDERL): Test whether <math.h> has an incompatible
        declaration of totalorderl, and set REPLACE_TOTALORDERL to 1 if so.

diff --git a/m4/totalorder.m4 b/m4/totalorder.m4
index 02c01fcd1a..ce264f4c65 100644
--- a/m4/totalorder.m4
+++ b/m4/totalorder.m4
@@ -9,22 +9,36 @@ AC_DEFUN([gl_FUNC_TOTALORDERF]
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
-  gl_MATHFUNC([totalorderf], [int],
-    [(float const *, float const *)],
-    [extern
-     #ifdef __cplusplus
-     "C"
-     #endif
-     int totalorderf (float const *, float const *);
+  dnl glibc versions < 2.31 had an incompatible declaration of this function,
+  dnl see 
<https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=42760d764649ad82f5fe45a26cbdf2c2500409f7>
+  AC_CACHE_CHECK([whether totalorderf has a non-standard declaration],
+    [gl_cv_func_totalorderf_incompatible],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <math.h>
+          ]],
+          [[extern
+            #ifdef __cplusplus
+            "C"
+            #endif
+            int totalorderf (float const *, float const *);
+          ]])
+       ],
+       [gl_cv_func_totalorderf_incompatible=no],
+       [gl_cv_func_totalorderf_incompatible=yes])
     ])
-  AS_IF([test $gl_cv_func_totalorderf_no_libm != yes &&
-         test $gl_cv_func_totalorderf_in_libm != yes],
-    [if test $gl_cv_func_totalorderf_in_libm != yes; then
-       HAVE_TOTALORDERF=0
-     else
-       REPLACE_TOTALORDERF=1
-     fi
-     TOTALORDERF_LIBM='$(ISNANF_LIBM)'])
+  if test $gl_cv_func_totalorderf_incompatible = yes; then
+    REPLACE_TOTALORDERF=1
+  else
+    gl_MATHFUNC([totalorderf], [int], [(float const *, float const *)])
+    if test $gl_cv_func_totalorderf_no_libm != yes \
+       && test $gl_cv_func_totalorderf_in_libm != yes; then
+      HAVE_TOTALORDERF=0
+    fi
+  fi
+  if test $HAVE_TOTALORDERF = 0 || test $REPLACE_TOTALORDERF = 1; then
+    TOTALORDERF_LIBM='$(ISNANF_LIBM)'
+  fi
   AC_SUBST([TOTALORDERF_LIBM])
 ])
 
@@ -33,22 +47,36 @@ AC_DEFUN([gl_FUNC_TOTALORDER]
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
-  gl_MATHFUNC([totalorder], [int],
-    [(double const *, double const *)],
-    [extern
-     #ifdef __cplusplus
-     "C"
-     #endif
-     int totalorder (double const *, double const *);
+  dnl glibc versions < 2.31 had an incompatible declaration of this function,
+  dnl see 
<https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=42760d764649ad82f5fe45a26cbdf2c2500409f7>
+  AC_CACHE_CHECK([whether totalorder has a non-standard declaration],
+    [gl_cv_func_totalorder_incompatible],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <math.h>
+          ]],
+          [[extern
+            #ifdef __cplusplus
+            "C"
+            #endif
+            int totalorder (double const *, double const *);
+          ]])
+       ],
+       [gl_cv_func_totalorder_incompatible=no],
+       [gl_cv_func_totalorder_incompatible=yes])
     ])
-  AS_IF([test $gl_cv_func_totalorder_no_libm != yes &&
-         test $gl_cv_func_totalorder_in_libm != yes],
-    [if test $gl_cv_func_totalorder_in_libm != yes; then
-       HAVE_TOTALORDER=0
-     else
-       REPLACE_TOTALORDER=1
-     fi
-     TOTALORDER_LIBM='$(ISNAND_LIBM)'])
+  if test $gl_cv_func_totalorder_incompatible = yes; then
+    REPLACE_TOTALORDER=1
+  else
+    gl_MATHFUNC([totalorder], [int], [(double const *, double const *)])
+    if test $gl_cv_func_totalorder_no_libm != yes \
+       && test $gl_cv_func_totalorder_in_libm != yes; then
+      HAVE_TOTALORDER=0
+    fi
+  fi
+  if test $HAVE_TOTALORDER = 0 || test $REPLACE_TOTALORDER = 1; then
+    TOTALORDER_LIBM='$(ISNAND_LIBM)'
+  fi
   AC_SUBST([TOTALORDER_LIBM])
 ])
 
@@ -57,24 +85,38 @@ AC_DEFUN([gl_FUNC_TOTALORDERL]
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
-  gl_MATHFUNC([totalorderl], [int],
-    [(long double const *, long double const *)],
-    [extern
-     #ifdef __cplusplus
-     "C"
-     #endif
-     int totalorderl (long double const *, long double const *);
-    ])
-  AS_IF([test $gl_cv_func_totalorderl_no_libm != yes &&
-         test $gl_cv_func_totalorderl_in_libm != yes],
-    [if test $gl_cv_func_totalorderl_in_libm != yes; then
-       HAVE_TOTALORDERL=0
-     else
-       REPLACE_TOTALORDERL=1
-     fi
-     TOTALORDERL_LIBM='$(ISNANL_LIBM)'
-     dnl Prerequisite of lib/totalorderl.c.
-     gl_LONG_DOUBLE_SIGN_LOCATION
+  dnl glibc versions < 2.31 had an incompatible declaration of this function,
+  dnl see 
<https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=42760d764649ad82f5fe45a26cbdf2c2500409f7>
+  AC_CACHE_CHECK([whether totalorderl has a non-standard declaration],
+    [gl_cv_func_totalorderl_incompatible],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <math.h>
+          ]],
+          [[extern
+            #ifdef __cplusplus
+            "C"
+            #endif
+            int totalorderl (long double const *, long double const *);
+          ]])
+       ],
+       [gl_cv_func_totalorderl_incompatible=no],
+       [gl_cv_func_totalorderl_incompatible=yes])
     ])
+  if test $gl_cv_func_totalorderl_incompatible = yes; then
+    REPLACE_TOTALORDERL=1
+  else
+    gl_MATHFUNC([totalorderl], [int],
+      [(long double const *, long double const *)])
+    if test $gl_cv_func_totalorderl_no_libm != yes \
+       && test $gl_cv_func_totalorderl_in_libm != yes; then
+      HAVE_TOTALORDERL=0
+    fi
+  fi
+  if test $HAVE_TOTALORDERL = 0 || test $REPLACE_TOTALORDERL = 1; then
+    TOTALORDERL_LIBM='$(ISNANL_LIBM)'
+    dnl Prerequisite of lib/totalorderl.c.
+    gl_LONG_DOUBLE_SIGN_LOCATION
+  fi
   AC_SUBST([TOTALORDERL_LIBM])
 ])