ghc-8.6.4-release tag fails to build on 64bit windows using default options.
There seems to be some issue with the haddock submodule/executable.
I did the usual ./boot && ./configure && make
"/c/Users/Andi/AppData/Roaming/cabal/bin//happy" -agc --strict compiler/cmm/CmmParse.y -o compiler/stage2/build/CmmParse.hs
"/c/Users/Andi/AppData/Roaming/cabal/bin//alex" -g --latin1 compiler/parser/Lexer.x -o compiler/stage2/build/Lexer.hs
sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.o|" -e "1s|^|compiler/ghci/|" -e "1s|compiler/|compiler/stage2/build/|" -e "1s|stage2/build/stage2/build|stage2/build|g" -e "s|^E:/ghc_86_src/||gi" compiler/stage2/build/.depend-v-p.c_asm.bit >> compiler/stage2/build/.depend-v-p.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.p_o|" -e "1s|^|compiler/ghci/|" -e "1s|compiler/|compiler/stage2/build/|" -e "1s|stage2/build/stage2/build|stage2/build|g" -e "s|^E:/ghc_86_src/||gi" compiler/stage2/build/.depend-v-p.c_asm.bit >> compiler/stage2/build/.depend-v-p.c_asm.tmp && true
"/c/Users/Andi/AppData/Roaming/cabal/bin//happy" -agc --strict compiler/parser/Parser.y -o compiler/stage2/build/Parser.hs
E:/ghc_86_src/inplace/mingw/bin/gcc.exe -E -DMAKING_GHC_BUILD_SYSTEM_DEPENDENCIES -fno-stack-protector -Wall -Icompiler/stage2/build/./autogen -Icompiler/. -Icompiler/parser -Icompiler/utils -Icompiler/../rts/dist/build -Icompiler/stage2 -Icompiler/stage2/build/. -Icompiler/stage2/build/parser -Icompiler/stage2/build/utils -Icompiler/stage2/build/../rts/dist/build -Icompiler/stage2/build/stage2 -DGHCI -I'E:\ghc_86_src\libraries\process\include' -I'E:\ghc_86_src\libraries\process/dist-install/build/include' -I'E:\ghc_86_src\libraries\process\dist-install\build\include' -I'E:\ghc_86_src\libraries\process\dist-install\build/dist-install/build/include' -I'E:\ghc_86_src\libraries\directory\.' -I'E:\ghc_86_src\libraries\directory\dist-install\build\.' -I'E:\ghc_86_src\libraries\time\lib/include' -I'E:\ghc_86_src\libraries\time\lib/dist-install/build/include' -I'E:\ghc_86_src\libraries\time\dist-install\build\lib/include' -I'E:\ghc_86_src\libraries\time\dist-install\build\lib/dist-install/build/include' -I'E:\ghc_86_src\libraries\containers\include' -I'E:\ghc_86_src\libraries\containers/dist-install/build/include' -I'E:\ghc_86_src\libraries\containers\dist-install\build\include' -I'E:\ghc_86_src\libraries\containers\dist-install\build/dist-install/build/include' -I'E:\ghc_86_src\libraries\Win32\include' -I'E:\ghc_86_src\libraries\Win32/dist-install/build/include' -I'E:\ghc_86_src\libraries\Win32\dist-install\build\include' -I'E:\ghc_86_src\libraries\Win32\dist-install\build/dist-install/build/include' -I'E:\ghc_86_src\libraries\bytestring\include' -I'E:\ghc_86_src\libraries\bytestring/dist-install/build/include' -I'E:\ghc_86_src\libraries\bytestring\dist-install\build\include' -I'E:\ghc_86_src\libraries\bytestring\dist-install\build/dist-install/build/include' -I'E:\ghc_86_src\libraries\base\include' -I'E:\ghc_86_src\libraries\base/dist-install/build/include' -I'E:\ghc_86_src\libraries\base\dist-install\build\include' -I'E:\ghc_86_src\libraries\base\dist-install\build/dist-install/build/include' -I'E:\ghc_86_src\libraries\integer-gmp\include' -I'E:\ghc_86_src\libraries\integer-gmp/dist-install/build/include' -I'E:\ghc_86_src\libraries\integer-gmp\dist-install\build\include' -I'E:\ghc_86_src\libraries\integer-gmp\dist-install\build/dist-install/build/include' -I'E:/ghc_86_src/rts/dist/build' -I'E:/ghc_86_src/includes' -I'E:/ghc_86_src/includes/dist-derivedconstants/header' -Wno-error=inline -MM -x c compiler/cbits/genSym.c -MF compiler/stage2/build/.depend-v-p.c_asm.bit
sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.o|" -e "1s|^|compiler/cbits/|" -e "1s|compiler/|compiler/stage2/build/|" -e "1s|stage2/build/stage2/build|stage2/build|g" -e "s|^E:/ghc_86_src/||gi" compiler/stage2/build/.depend-v-p.c_asm.bit >> compiler/stage2/build/.depend-v-p.c_asm.tmp && sed -e 's|\\|/|g' -e 's| /$| \\|' -e "1s|\.o|\.p_o|" -e "1s|^|compiler/cbits/|" -e "1s|compiler/|compiler/stage2/build/|" -e "1s|stage2/build/stage2/build|stage2/build|g" -e "s|^E:/ghc_86_src/||gi" compiler/stage2/build/.depend-v-p.c_asm.bit >> compiler/stage2/build/.depend-v-p.c_asm.tmp && true
"rm" -f compiler/stage2/build/.depend-v-p.c_asm.bit
echo "compiler_stage2_depfile_c_asm_EXISTS = YES" >> compiler/stage2/build/.depend-v-p.c_asm.tmp
mv compiler/stage2/build/.depend-v-p.c_asm.tmp compiler/stage2/build/.depend-v-p.c_asm
"inplace/bin/hsc2hs.exe" '--cc=E:/ghc_86_src/inplace/mingw/bin/gcc.exe' '--ld=E:/ghc_86_src/inplace/mingw/bin/gcc.exe' --cflag=-Wall --cflag=-fno-stack-protector --cflag=-Dx86_64_HOST_ARCH --cflag=-Dmingw32_HOST_OS --cflag=-D__GLASGOW_HASKELL__=806 '--cflag=-fno-stack-protector' '--cflag=-Wall' '--cflag=-Icompiler/stage2/build/./autogen' '--cflag=-Icompiler/.' '--cflag=-Icompiler/parser' '--cflag=-Icompiler/utils' '--cflag=-Icompiler/../rts/dist/build' '--cflag=-Icompiler/stage2' '--cflag=-Icompiler/stage2/build/.' '--cflag=-Icompiler/stage2/build/parser' '--cflag=-Icompiler/stage2/build/utils' '--cflag=-Icompiler/stage2/build/../rts/dist/build' '--cflag=-Icompiler/stage2/build/stage2' '--cflag=-DGHCI' '--cflag=-IE:\ghc_86_src\libraries\process\include' '--cflag=-IE:\ghc_86_src\libraries\process/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\process\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\process\dist-install\build/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\directory\.' '--cflag=-IE:\ghc_86_src\libraries\directory\dist-install\build\.' '--cflag=-IE:\ghc_86_src\libraries\time\lib/include' '--cflag=-IE:\ghc_86_src\libraries\time\lib/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\time\dist-install\build\lib/include' '--cflag=-IE:\ghc_86_src\libraries\time\dist-install\build\lib/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\containers\include' '--cflag=-IE:\ghc_86_src\libraries\containers/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\containers\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\containers\dist-install\build/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\Win32\include' '--cflag=-IE:\ghc_86_src\libraries\Win32/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\Win32\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\Win32\dist-install\build/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\bytestring\include' '--cflag=-IE:\ghc_86_src\libraries\bytestring/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\bytestring\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\bytestring\dist-install\build/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\base\include' '--cflag=-IE:\ghc_86_src\libraries\base/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\base\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\base\dist-install\build/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\integer-gmp\include' '--cflag=-IE:\ghc_86_src\libraries\integer-gmp/dist-install/build/include' '--cflag=-IE:\ghc_86_src\libraries\integer-gmp\dist-install\build\include' '--cflag=-IE:\ghc_86_src\libraries\integer-gmp\dist-install\build/dist-install/build/include' '--cflag=-IE:/ghc_86_src/rts/dist/build' '--cflag=-IE:/ghc_86_src/includes' '--cflag=-IE:/ghc_86_src/includes/dist-derivedconstants/header' '--cflag=-Wno-error=inline' --cflag=-Icompiler/stage2/build/./autogen --cflag=-include --cflag=compiler/stage2/build/./autogen/cabal_macros.h compiler/utils/Fingerprint.hsc -o compiler/stage2/build/Fingerprint.hs
E:/ghc_86_src/inplace/mingw/bin/gcc.exe -E -undef -traditional -P -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Icompiler/stage2 -x c compiler/prelude/primops.txt.pp | grep -v '^#pragma GCC' > compiler/stage2/build/primops.txt
"rm" -f utils/haddock/dist/build/.depend.c_asm.tmp
utils/haddock/ghc.mk:20: utils/haddock/dist/build/.depend.haskell: No such file or directory
make[1]: *** No rule to make target 'utils/haddock/dist/build/Main.hs', needed by 'utils/haddock/dist/build/.depend.haskell'. Stop.
make[1]: *** Waiting for unfinished jobs....
"rm" -f utils/haddock/dist/build/.depend.c_asm.bit
echo "utils/haddock_dist_depfile_c_asm_EXISTS = YES" >> utils/haddock/dist/build/.depend.c_asm.tmp
mv utils/haddock/dist/build/.depend.c_asm.tmp utils/haddock/dist/build/.depend.c_asm
unused terminals: 2
make: *** [Makefile:127: all] Error 2
I've tried to wipe the haddock folder completely and restoring it via submodule update to no avail. Disabling haddock generation at least allows the build to proceed as a workaround.
I don't think this is all too important but better to document it than not.