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unix-adapter: Link statically with cyggcc_s-1.dll and cygstdc++-6.dll.

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* At least for now, I'm shipping Cygwin/MSYS binaries.  On Cygwin (but
   not MSYS), the console.exe executable previously linked dynamically
   to cyggcc_s-1.dll and cygstdc++-6.dll.

   Linking dynamically with cygstdc++-6.dll seems risky for a binary
   not distributed by Cygwin, because G++'s Windows ABI is unstable, at
   least as of G++ 4.7, which turned on the __thiscall calling
   convention.  If a binary I ship ever comes into contact with a
   4.7-versioned cygstdc++-6.dll, then my binary will (very likely)
   segfault.

   So far, I've only observed this ABI incompatibility with MinGW,
   where a sufficiently upgraded MinGW configuration comes with a
   libstdc++-6.dll that is completely incompatible with every previous
   libstdc++-6.dll, so that every program built against the older
   libstdc++-6.dll segfaults immediately.  For now, Cygwin seems stuck
   at G++ 4.5, and my impression (possibly incorrect), is that G++'s
   Windows ABI was stable prior to 4.7.  I think G++'s Linux ABI is
   stable.  Presumably Cygwin will eventually update its compiler,
   though, so it makes sense to fix the problem early.

   I believe I originally chose to dynamically link the libraries
   because it was the default behavior, and I was afraid that a
   non-default option would break something.  It turns out that
   linking statically with cygstdc++-6 *does* break something -- it
   causes linker errors if the code uses std::cerr.  The workaround
   is not to use std::cerr.  This is not a problem for the
   unix-adapter, which already has to put up with MSYS' gimpy G++ 3.4
   compiler.
This commit is contained in:
Ryan Prichard 2012-12-12 11:35:41 +00:00
parent bb42d17941
commit 549472ec78
2 changed files with 6 additions and 1 deletions
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5
configure vendored
View File

@ -54,12 +54,16 @@ case $(uname -s) in
IS_CYGWIN=1
UNIX_GPP=i686-pc-cygwin-g++
MINGW_GPP="i686-pc-mingw32-g++ i686-w64-mingw32-g++"
UNIX_LDFLAGS_STATIC_LIBSTDCXX="-static-libgcc -static-libstdc++"
;;
MINGW*)
echo 'uname -s identifies a MSYS environment.'
IS_MSYS=1
UNIX_GPP=i686-pc-msys-g++
MINGW_GPP=mingw32-g++
# The MSYS compiler does not recognize -static-libstdc++. There is a
# msys-1.0.dll, but no gcc or stdc++ DLL.
UNIX_LDFLAGS_STATIC_LIBSTDCXX=
;;
*)
echo 'Error: uname -s did not match either CYGWIN* or MINGW*.'
@ -76,5 +80,6 @@ MINGW_GPP=$FINDTOOL_OUT
# Write config files.
echo Writing config-unix.mk
echo CXX=$UNIX_GPP > config-unix.mk
echo LDFLAGS_STATIC_LIBSTDCXX=$UNIX_LDFLAGS_STATIC_LIBSTDCXX >> config-unix.mk
echo Writing config-mingw.mk
echo CXX=$MINGW_GPP > config-mingw.mk

2
unix-adapter/Makefile
View File

@ -24,7 +24,7 @@ include ../config-unix.mk
PROGRAM = ../build/console.exe
OBJECTS = main.o Shared.o
CXXFLAGS += -I../include
LDFLAGS += ../build/winpty.dll
LDFLAGS += $(LDFLAGS_STATIC_LIBSTDCXX) ../build/winpty.dll
all : $(PROGRAM)