Rebased 99a1523 -> f2b7ea4 (pr21344.01 -> pr21344.02) due to the conflict with #21339.

@fanquake

Please rebase this, and remove/trim the link error output from the PR description. There's no need to have all of that pasted in there.

Done.

Looks like this might also fix the issue of cross compiling libbitcoinconsensus for windows when building on macOS:

# Using brew installed Mingw-w64 v8.0.0 (based  on GCC 10.2).

  CXXLD    libbitcoinconsensus.la
/usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/bin/x86_64-w64-mingw32-ld: /usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/x86_64-w64-mingw32/lib/libssp.a(ssp.o): in function `__stack_chk_fail':
/private/tmp/mingw-w64-20210210-85400-sa28mi/mingw-w64-v8.0.0/gcc/build-x86_64/x86_64-w64-mingw32/libssp/../../../libssp/ssp.c:183: multiple definition of `__stack_chk_fail'; /usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/x86_64-w64-mingw32/lib/../lib/libssp.dll.a(d000007.o):(.text+0x0): first defined here
collect2: error: ld returned 1 exit status

@fanquake

Looks like this might also fix the issue of cross compiling libbitcoinconsensus for windows when building on macOS:

# Using brew installed Mingw-w64 v8.0.0 (based  on GCC 10.2).

  CXXLD    libbitcoinconsensus.la
/usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/bin/x86_64-w64-mingw32-ld: /usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/x86_64-w64-mingw32/lib/libssp.a(ssp.o): in function `__stack_chk_fail':
/private/tmp/mingw-w64-20210210-85400-sa28mi/mingw-w64-v8.0.0/gcc/build-x86_64/x86_64-w64-mingw32/libssp/../../../libssp/ssp.c:183: multiple definition of `__stack_chk_fail'; /usr/local/Cellar/mingw-w64/8.0.0_3/toolchain-x86_64/x86_64-w64-mingw32/lib/../lib/libssp.dll.a(d000007.o):(.text+0x0): first defined here
collect2: error: ld returned 1 exit status

You are right. Tested on macOS Mojave 10.14.6 (18G8022) with Homebrew's make:

• master (a22653a) -- the same error as above

• this PR, merged into the current master (a22653a):

$ make -C depends HOST=x86_64-w64-mingw32 NO_QT=1
$ ./autogen.sh
$ CONFIG_SITE=$PWD/depends/x86_64-w64-mingw32/share/config.site ./configure
$ make

@luke-jr

Won't this produce the wrong output?

You're right. The libbitcoinconsensus-0.dll is not produced with this PR.

Closing.