bug#30128: MSVC: 'invalid numeric argument '/Wl, -DLL, -IMPLIB:.libs...' error for shared GMP builds on Windows

[sav_ix]

Hello everyone,

For GMP build using MSVC got error:
===============================================================
make[2]: Entering directory '/c/libGMP-6.1.99-dev/build'
/bin/sh
 ./libtool  --tag=CXX   --mode=link cl  -Zc:wchar_t -FS -nologo -DWIN32 
-D_WIN32 -DWIN64 -D_WIN64 -DUNICODE -D_UNICODE 
-D_CRT_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_DEPRECATE -GR -EHsc -O2 
-DNDEBUG -D_NDEBUG -MD -no-undefined  -version-info 9:0:5  -o 
libgmpxx.la -rpath /c/libGMP-6.1.99-dev/build/../MSVC64RH/lib 
cxx/dummy.lo cxx/isfuns.lo cxx/ismpf.lo cxx/ismpq.lo cxx/ismpz.lo 
cxx/ismpznw.lo cxx/limits.lo cxx/osdoprnti.lo cxx/osfuns.lo cxx/osmpf.lo
 cxx/osmpq.lo cxx/osmpz.lo libgmp.la
libtool: link: rm -fr  .libs/gmpxx.exp
libtool:
 link: /usr/bin/nm -B  cxx/.libs/dummy.obj cxx/.libs/isfuns.obj 
cxx/.libs/ismpf.obj cxx/.libs/ismpq.obj cxx/.libs/ismpz.obj 
cxx/.libs/ismpznw.obj cxx/.libs/limits.obj cxx/.libs/osdoprnti.obj 
cxx/.libs/osfuns.obj cxx/.libs/osmpf.obj cxx/.libs/osmpq.obj 
cxx/.libs/osmpz.obj   | sed -n -e 's/^.*[        
]\([ABCDGIRSTW][ABCDGIRSTW]*\)[         ][      
]*\([_A-Za-z][_A-Za-z0-9]*\)\{0,1\}$/\1 \2 \2/p' | sed '/ __gnu_lto/d' |
 /usr/bin/sed 's/.* //' | sort | uniq > .libs/gmpxx.exp
libtool: 
link: if test DEF = "`/usr/bin/sed -n -e 's/^[  ]*//' -e '/^\(;.*\)*$/d'
 -e 's/^\(EXPORTS\|LIBRARY\)\([         ].*\)*$/DEF/p' -e q 
.libs/gmpxx.exp`" ; then cp ".libs/gmpxx.exp" ".libs/gmpxx-4.dll.def"; 
echo ".libs\\gmpxx-4.dll.def" > ".libs/gmpxx-4.dll.exp"; else 
/usr/bin/sed -e 's/^/-link -EXPORT:/' < .libs/gmpxx.exp > 
.libs/gmpxx-4.dll.exp; fi
libtool: link:  cl -o .libs\\gmpxx-4.dll  
cxx/.libs/dummy.obj cxx/.libs/isfuns.obj cxx/.libs/ismpf.obj 
cxx/.libs/ismpq.obj cxx/.libs/ismpz.obj cxx/.libs/ismpznw.obj 
cxx/.libs/limits.obj cxx/.libs/osdoprnti.obj cxx/.libs/osfuns.obj 
cxx/.libs/osmpf.obj cxx/.libs/osmpq.obj cxx/.libs/osmpz.obj   -FS -O2   
 ./.libs/gmp.lib "@.libs\\gmpxx-4.dll.exp" 
-Wl,-DLL,-IMPLIB:".libs\\gmpxx.lib"
Microsoft (R) C/C++ Optimizing Compiler Version 19.12.25830.2 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

cl : Command line warning D9035 : option 'o' has been deprecated and will be removed in a future release
cl : Command line error D8021 : invalid numeric argument '/Wl,-DLL,-IMPLIB:.libs\gmpxx.lib'
make[2]: *** [Makefile:876: libgmpxx.la] Error 2
make[2]: Leaving directory '/c/libGMP-6.1.99-dev/build'
make[1]: *** [Makefile:963: all-recursive] Error 1
make[1]: Leaving directory '/c/libGMP-6.1.99-dev/build'
make: *** [Makefile:778: all] Error 2
===============================================================

which relate to improperC++ compiler use.


Reproduced for:
- shared builds using MSVC,

not reproduced for:
- static builds using MSVC,
- shared builds using mingw-w64.


Environment:
  - Windows 10 x64,
  - MSVC 2017 15.5.0,
  - Windows SDK 10.0.16299.15,
  - mingw-w64 x86_64 7.2.0,
  - MSYS2 x86_64 20170918,
  - libiconv 1.15.


The source of error is missing workaround for CXX compilers via 'compile' script, which enabled in '_AM_PROG_CC_C_O' (http://git.savannah.gnu.org/cgit/automake.git/tree/m4/prog-cc-c-o.m4) subroutine for C compilers only. This results to improper C++ compiler features check during configuration:
===============================================================
CC="cl" CXX="cl" ./configure && make

<snip>

checking whether cl understands -c and -o together... no

<snip>

checking if /c/libGMP-6.1.99-dev/build/compile cl supports -c -o file.obj... yes    <== C compiler features check

<snip>

checking if cl supports -c -o file.obj... no    <== C++ compiler features check
===============================================================

and setting improper values to C++ compiler-related variables:
===============================================================
CC='/c/libGMP-6.1.99-dev/build/compile cl'
CPP='/c/libGMP-6.1.99-dev/build/compile cl -E'

<snip>

CXX='cl'
CXXCPP='cl -E'
===============================================================

in 'configure.log' and makefiles.


A workaround is to apply patch:
===============================================================
    # A longer-term fix would be to have automake use am__CC in this case,
    # and then we could set am__CC="\$(top_srcdir)/compile \$(CC)"
    CC="$am_aux_dir/compile $CC"
+   CXX="$am_aux_dir/compile $CXX"
 fi
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
===============================================================

 to file 'm4/prog-cc-c-o.m4' and update GMP build system. Then error not reproduced, and all build tasks finishes successfully.

Can this patch be merged to Automake sources? Or it it possible to add '_AM_PROG_CXX_C_O' or other subroutine for C++ compilers check, similar to '_AM_PROG_CC_C_O' for C compilers, which would provide this fix.


Best,

Alexander