bug#15831: Absolute library paths with Cygwin + MSVC cl

[Tony Kelman]

Hi all,

I'm working with a set of projects that save their inter-dependencies in
AC_SUBST variables as absolute paths to the relevant .la files. In Cygwin
using the MSVC cl compiler and building only static libraries, I'm seeing
libtool replace the Unix-style absolute path to .la files with the
Unix-style absolute path to the corresponding .libs/<libname>.lib file.
Unsurprisingly, the cl compiler doesn't understand the Unix-style path.
If I modify the Makefile to add `cygpath -w ...` around the absolute path
to the .la file, then libtool instead replaces the Windows-style absolute
path to the .la file with just ./.libs/<libname>.lib, which isn't right
since I'm in a different directory than that library was built in.

My test case here is the COIN-OR Open Solver Interface project
(https://projects.coin-or.org/Osi/wiki) release 0.106.2, but updated to a
recent set of autotools by svn switch'ing the BuildTools directory to
https://projects.coin-or.org/BuildTools/browser/branches/autotools-update.
The same behavior described below happens with the very old libtool
(1.5.22) distributed with the release, but I updated to test whether the
problem still exists in recent libtool. Started Cygwin (64-bit) from the
"VS Command Prompt" to set the right environment variables, and configured
Osi with --enable-doscompile=msvc to use cl compiler.

The problem comes at make test. With the Unix-style absolute path to the
.la file in the variable OSILIB_LIBS, the problem invocation looks like:

/bin/sh ../libtool --tag=CXX -n -v  --mode=link cl  -MT -O2 -nologo -EHsc
 -GR -wd4996 -D_CRT_SECURE_NO_DEPRECATE -DNDEBUG    -DOSI_BUILD   -o
 unitTest.exe unitTest.obj OsiTestSolver.obj OsiTestSolverInterface.obj
 OsiTestSolverInterfaceIO.obj OsiTestSolverInterfaceTest.obj
 ../src/OsiCommonTest/libOsiCommonTests.la       ../src/Osi/libOsi.la
 /home/Tony/Osi-0.106.2/build02/CoinUtils/src/libCoinUtils.la
libtool: link: cl -MT -O2 -nologo -EHsc -GR -wd4996
 -D_CRT_SECURE_NO_DEPRECATE -DNDEBUG -DOSI_BUILD -o unitTest.exe
 unitTest.obj OsiTestSolver.obj OsiTestSolverInterface.obj
 OsiTestSolverInterfaceIO.obj OsiTestSolverInterfaceTest.obj
 ../src/OsiCommonTest/.libs/OsiCommonTests.lib ../src/Osi/.libs/Osi.lib
 /home/Tony/Osi-0.106.2/build02/CoinUtils/src/.libs/libCoinUtils.lib
libtool: link: lt_outputfile="unitTest.exe"
libtool: link:  lt_tool_outputfile="unitTest.exe"
libtool: link:  case  in *.exe|*.EXE) ;; *) lt_outputfile=".exe"
 lt_tool_outputfile=".exe" ;; esac
libtool: link:  func_to_tool_file ""
libtool: link:  if test "mt" != ":" && test -f ".manifest"; then mt
 -manifest ".manifest" -outputresource:"" || exit 1; rm -f ".manifest"; fi

If I take out -n from AM_LIBTOOLFLAGS then I get hundreds of unresolved
externals to everything from libCoinUtils, since cl ignored the "unknown
option" of the Unix-style absolute path to libCoinUtils.la.

Adding `cygpath -w ...` around the absolute path to libCoinUtils.la in the
Osi/test/Makefile variable OSILIB_LIBS results in the following:

/bin/sh ../libtool --tag=CXX -v  --mode=link cl  -MT -O2 -nologo -EHsc
 -GR -wd4996 -D_CRT_SECURE_NO_DEPRECATE -DNDEBUG    -DOSI_BUILD   -o
 unitTest.exe unitTest.obj OsiTestSolver.obj OsiTestSolverInterface.obj
 OsiTestSolverInterfaceIO.obj OsiTestSolverInterfaceTest.obj
 ../src/OsiCommonTest/libOsiCommonTests.la       ../src/Osi/libOsi.la
 `cygpath -w /home/Tony/Osi-0.106.2/build02/CoinUtils/src/libCoinUtils.la`
libtool: link: cl -MT -O2 -nologo -EHsc -GR -wd4996
 -D_CRT_SECURE_NO_DEPRECATE -DNDEBUG -DOSI_BUILD -o unitTest.exe
 unitTest.obj OsiTestSolver.obj OsiTestSolverInterface.obj
 OsiTestSolverInterfaceIO.obj OsiTestSolverInterfaceTest.obj
 ../src/OsiCommonTest/.libs/OsiCommonTests.lib ../src/Osi/.libs/Osi.lib
 ./.libs/libCoinUtils.lib
cl : Command line warning D9035 : option 'o' has been deprecated and will
 be removed in a future release
LINK : fatal error LNK1181: cannot open input file 
'./.libs/libCoinUtils.lib'
libtool: link: lt_outputfile="unitTest.exe"
libtool: link:  lt_tool_outputfile="unitTest.exe"
libtool: link:  case unitTest.exe in *.exe|*.EXE) ;; *)
 lt_outputfile="unitTest.exe.exe" lt_tool_outputfile="unitTest.exe.exe" ;; 
esac
libtool: link:  func_to_tool_file "unitTest.exe"
libtool: link:  if test "mt" != ":" && test -f "unitTest.exe.manifest";
 then mt -manifest "unitTest.exe.manifest" -outputresource:"unitTest.exe"
 || exit 1; rm -f "unitTest.exe.manifest"; fi
Makefile:476: recipe for target 'unitTest.exe' failed
make: *** [unitTest.exe] Error 2

Is this a bug in libtool, or am I doing something wrong/unsupported? MSYS
works better here, but it would be ideal to be able to use Cygwin as well.

Relevant info from the end of libtool --help:

host-triplet:    x86_64-unknown-cygwin
shell:        /bin/sh
compiler:        cl
compiler 
flags:        -MT -O2 -nologo -wd4996 -D_CRT_SECURE_NO_DEPRECATE -DNDEBUG
linker:        link (gnu? no)
libtool:    (GNU libtool) 2.4.2
automake:
autoconf:    autoconf (GNU Autoconf) 2.69

Automake was version 1.12, not sure why libtool didn't see that.

Appreciate any advice here, let me know if there's any more information I
can provide that would be useful.

-Tony