[Bug bootstrap/108011] New: [13 Regression] gcc-13-20221204 failure to build on Cygwin: ‘uc_mcontext’ has incomplete type

[mckelvey at maskull dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108011

            Bug ID: 108011
           Summary: [13 Regression] gcc-13-20221204 failure to build on
                    Cygwin: ‘uc_mcontext’ has incomplete type
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mckelvey at maskull dot com
  Target Milestone: ---

Created attachment 54035
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54035&action=edit
Build log with failure

This worked two snapshots ago.

/home/McKelvey/gcc-13-20221204/host-x86_64-pc-cygwin/gcc/xgcc
-B/home/McKelvey/gcc-13-20221204/host-x86_64-pc-cygwin/gcc/
-B/usr/local/x86_64-pc-cygwin/bin/ -B/usr/local/x86_64-pc-cygwin/lib/ -isystem
/usr/local/x86_64-pc-cygwin/include -isystem
/usr/local/x86_64-pc-cygwin/sys-include   -fno-checking -g -O2 -m32 -O2
-I../../.././libgcc/../winsup/w32api/include
-I../../.././libgcc/../winsup/include
-I../../.././libgcc/../winsup/cygwin/include -g -O2 -DIN_GCC    -W -Wall
-Wno-narrowing -Wwrite-strings -Wcast-qual -Wno-format -Wstrict-prototypes
-Wmissing-prototypes -Wold-style-definition  -isystem ./include   -g
-DIN_LIBGCC2 -fbuilding-libgcc -fno-stack-protector   -I. -I.
-I../../../host-x86_64-pc-cygwin/gcc -I../../.././libgcc -I../../.././libgcc/.
-I../../.././libgcc/../gcc -I../../.././libgcc/../include
-I../../.././libgcc/config/libbid -DENABLE_DECIMAL_BID_FORMAT -DHAVE_CC_TLS
-DUSE_EMUTLS  -o _muldi3.o -MT _muldi3.o -MD -MP -MF _muldi3.dep -DL_muldi3 -c
../../.././libgcc/libgcc2.c
In file included from /usr/include/sys/signal.h:23,
                 from /usr/include/signal.h:6,
                 from /usr/include/time.h:158,
                 from ../../.././libgcc/../gcc/tsystem.h:108,
                 from ../../.././libgcc/libgcc2.c:27:
/usr/include/cygwin/signal.h:102:2: error: #error unimplemented for this target
  102 | #error unimplemented for this target
      |  ^~~~~
In file included from /usr/include/sys/signal.h:379:
/usr/include/sys/ucontext.h:17:25: error: field ‘uc_mcontext’ has incomplete
type
   17 |         mcontext_t      uc_mcontext;
      |                         ^~~~~~~~~~~
make[5]: *** [Makefile:501: _muldi3.o] Error 1

$ uname
CYGWIN_NT-10.0-19044

$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-pc-cygwin/13.0.0/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with: ./configure --enable-languages=c,c++ --enable-threads=posix
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.0.0 20221118 (experimental) (GCC)

./configure --enable-languages=c,c++ --enable-threads=posix