Restore exclusion of "gcc_eh" from implicit link libraries

Since commit v3.9.0-rc1~148^2 (Do not assume GCC libs are linked by all
compilers, 2017-05-05) we no longer filter out all `gcc*` implicit link
libraries.  This allows mixing of gcc and non-gcc compilers across
languages.  However, this caused a subtle problem with how GCC makes
exception handling symbols available to linked binaries.

GCC (at least on MinGW) provides two different libraries with exception
handling symbols:

* gcc_s: A shared library with -fvisibility=default, used by -shared-libgcc.
* gcc_eh: A static library with -fvisibility=hidden, used by -static-libgcc.

The C compiler (on MinGW) defaults to -static-libgcc and uses gcc_eh.
The C++ compiler defaults to -shared-libgcc and uses gcc_s when linking
shared libraries and executables so that exceptions can propagate across
shared libraries [1].  When linking a mixed-language binary, the C++
compiler should be used along with its choice of gcc_s.  In this case
gcc_eh should not be added even though the C compiler implies it because
gcc_s supersedes it.

Since the above-mentioned change, CMake is adding gcc_eh to C++ link
lines that also contain C code on MinGW.  This causes both gcc_s and
gcc_eh to be used, which is incorrect.  We can fix this simply by
excluding gcc_eh from the C compiler's implicit link libraries.

[1] https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Link-Options.html#Link-Options

Fixes: #17436

2 files changed, 22 insertions, 2 deletions

diff --git a/Modules/CMakeParseImplicitLinkInfo.cmake b/Modules/CMakeParseImplicitLinkInfo.cmake
index 3b77278..63d18ab 100644
--- a/Modules/CMakeParseImplicitLinkInfo.cmake
+++ b/Modules/CMakeParseImplicitLinkInfo.cmake
@@ -142,7 +142,7 @@ function(CMAKE_PARSE_IMPLICIT_LINK_INFO text lib_var dir_var fwk_var log_var obj
   # We remove items that are not language-specific.
   set(implicit_libs "")
   foreach(lib IN LISTS implicit_libs_tmp)
-    if("x${lib}" MATCHES "^x(crt.*\\.o|System.*|.*libclang_rt.*|msvcrt.*|libvcruntime.*|libucrt.*|libcmt.*)$")
+    if("x${lib}" MATCHES "^x(crt.*\\.o|gcc_eh.*|System.*|.*libclang_rt.*|msvcrt.*|libvcruntime.*|libucrt.*|libcmt.*)$")
       string(APPEND log "  remove lib [${lib}]\n")
     elseif(IS_ABSOLUTE "${lib}")
       get_filename_component(abs "${lib}" ABSOLUTE)
diff --git a/Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in b/Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in
index d7d881e..65487bb 100644
--- a/Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in
+++ b/Tests/CMakeTests/ImplicitLinkInfoTest.cmake.in
@@ -525,6 +525,27 @@ set(msys_g77_dirs "C:/some-mingw/lib/gcc/mingw32/3.4.5;C:/some-mingw/lib/gcc;/so
 list(APPEND platforms msys_g77)
 
 #-----------------------------------------------------------------------------
+# MSYS2
+
+# gcc dummy.c -v
+set(msys2_gcc_text " C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/collect2.exe -plugin C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/liblto_plugin-0.dll -plugin-opt=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/lto-wrapper.exe -plugin-opt=-fresolution=C:/msys64/tmp/ccikz9Wf.res -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -plugin-opt=-pass-through=-lpthread -plugin-opt=-pass-through=-ladvapi32 -plugin-opt=-pass-through=-lshell32 -plugin-opt=-pass-through=-luser32 -plugin-opt=-pass-through=-lkernel32 -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_eh -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -m i386pep -Bdynamic C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtbegin.o -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0 -LC:/msys64/mingw64/bin/../lib/gcc -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../.. C:/msys64/tmp/ccK0dTUv.o -lmingw32 -lgcc -lgcc_eh -lmoldname -lmingwex -lmsvcrt -lpthread -ladvapi32 -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc -lgcc_eh -lmoldname -lmingwex -lmsvcrt C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/default-manifest.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtend.o")
+set(msys2_gcc_libs "mingw32;gcc;moldname;mingwex;pthread;advapi32;shell32;user32;kernel32;mingw32;gcc;moldname;mingwex")
+set(msys2_gcc_dirs "C:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0;C:/msys64/mingw64/lib/gcc;C:/msys64/mingw64/x86_64-w64-mingw32/lib;C:/msys64/mingw64/lib")
+list(APPEND platforms msys2_gcc)
+
+# g++ dummy.cxx -v
+set(msys2_g++_text " C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/collect2.exe -plugin C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/liblto_plugin-0.dll -plugin-opt=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/lto-wrapper.exe -plugin-opt=-fresolution=C:/msys64/tmp/ccJQgvbN.res -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -plugin-opt=-pass-through=-lpthread -plugin-opt=-pass-through=-ladvapi32 -plugin-opt=-pass-through=-lshell32 -plugin-opt=-pass-through=-luser32 -plugin-opt=-pass-through=-lkernel32 -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -m i386pep -Bdynamic C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtbegin.o -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0 -LC:/msys64/mingw64/bin/../lib/gcc -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../.. C:/msys64/tmp/ccqPpuVS.o -lstdc++ -lmingw32 -lgcc_s -lgcc -lmoldname -lmingwex -lmsvcrt -lpthread -ladvapi32 -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc_s -lgcc -lmoldname -lmingwex -lmsvcrt C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/default-manifest.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtend.o")
+set(msys2_g++_libs "stdc++;mingw32;gcc_s;gcc;moldname;mingwex;pthread;advapi32;shell32;user32;kernel32;mingw32;gcc_s;gcc;moldname;mingwex")
+set(msys2_g++_dirs "C:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0;C:/msys64/mingw64/lib/gcc;C:/msys64/mingw64/x86_64-w64-mingw32/lib;C:/msys64/mingw64/lib")
+list(APPEND platforms msys2_g++)
+
+# gfortran dummy.f90 -v
+set(msys2_gfortran_text " C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/collect2.exe -plugin C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/liblto_plugin-0.dll -plugin-opt=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/lto-wrapper.exe -plugin-opt=-fresolution=C:/msys64/tmp/cczOKIDy.res -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -plugin-opt=-pass-through=-lquadmath -plugin-opt=-pass-through=-lm -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -plugin-opt=-pass-through=-lpthread -plugin-opt=-pass-through=-ladvapi32 -plugin-opt=-pass-through=-lshell32 -plugin-opt=-pass-through=-luser32 -plugin-opt=-pass-through=-lkernel32 -plugin-opt=-pass-through=-lmingw32 -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmoldname -plugin-opt=-pass-through=-lmingwex -plugin-opt=-pass-through=-lmsvcrt -m i386pep -Bdynamic C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtbegin.o -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0 -LC:/msys64/mingw64/bin/../lib/gcc -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib -LC:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../.. C:/msys64/tmp/ccyXuCgD.o -lgfortran -lmingw32 -lgcc_s -lgcc -lmoldname -lmingwex -lmsvcrt -lquadmath -lm -lmingw32 -lgcc_s -lgcc -lmoldname -lmingwex -lmsvcrt -lpthread -ladvapi32 -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc_s -lgcc -lmoldname -lmingwex -lmsvcrt C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/../../../../x86_64-w64-mingw32/lib/../lib/default-manifest.o C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.2.0/crtend.o")
+set(msys2_gfortran_libs "gfortran;mingw32;gcc_s;gcc;moldname;mingwex;quadmath;m;mingw32;gcc_s;gcc;moldname;mingwex;pthread;advapi32;shell32;user32;kernel32;mingw32;gcc_s;gcc;moldname;mingwex")
+set(msys2_gfortran_dirs "C:/msys64/mingw64/lib/gcc/x86_64-w64-mingw32/7.2.0;C:/msys64/mingw64/lib/gcc;C:/msys64/mingw64/x86_64-w64-mingw32/lib;C:/msys64/mingw64/lib")
+list(APPEND platforms msys2_gfortran)
+
+#-----------------------------------------------------------------------------
 # MSVC from NVIDIA CUDA
 
 set(nvcc_msvc_text [[cuda-fake-ld cl.exe -nologo "tmp/a_dlink.obj" "tmp/CMakeCUDACompilerId.obj" -link -INCREMENTAL:NO   "/LIBPATH:C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v8.0/bin/../lib/x64" cudadevrt.lib  cudart_static.lib -Fe"a.exe"]])
@@ -532,7 +553,6 @@ set(nvcc_msvc_libs "cudadevrt.lib;cudart_static.lib")
 set(nvcc_msvc_dirs "C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v8.0/lib/x64")
 list(APPEND platforms nvcc_msvc)
 
-
 #-----------------------------------------------------------------------------
 # PGI on Windows