...
/nix/store/gahx1w92ldx16a3nacdhi4z050ikzii1-python3.7-sphinx-1.8.3/bin/sphinx-build -b man -d docs/users_guide/.doctrees-man docs/users_guide docs/users_guide/build-man

looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 25%] index
writing output... [ 50%] intro
writing output... [ 75%] invoking
writing output... [100%] markup

/build/ghc-8.4.4/utils/haddock/doc/invoking.rst:457: WARNING: unknown option: -cpp
generating indices... genindex
writing additional pages... searchRunning Sphinx v1.8.3

copying static files... Running Sphinx v1.8.3
done
copying extra files... done
dumping search index in English (code: en) ... done
dumping object inventory... done
build succeeded, 1 warning.

The HTML pages are in .build-html.
cp -R utils/haddock/doc/.build-html utils/haddock/doc/haddock
"inplace/bin/mkdirhier" utils/count_lines/dist//.
"inplace/bin/mkdirhier" utils/compare_sizes/dist-install/build/tmp//.
"inplace/bin/mkdirhier" iserv/stage2/build/cbits//.
"inplace/bin/mkdirhier" iserv/stage2/build/tmp//.
"inplace/bin/mkdirhier" iserv/stage2_p/build/cbits//.
"inplace/bin/mkdirhier" iserv/stage2_p/build/tmp//.
"inplace/bin/mkdirhier" iserv/stage2_dyn/build/cbits//.
"inplace/bin/mkdirhier" iserv/stage2_dyn/build/tmp//.
"inplace/bin/ghc-stage1" -o utils/unlit/dist-install/build/tmp/unlit -hisuf dyn_hi -osuf  dyn_o -hcsuf dyn_hc -fPIC -dynamic  -H32m -O -Wall       -i -iutils/unlit/. -iutils/unlit/dist-install/build -Iutils/unlit/dist-install/build -iutils/unlit/dist-install/build/unlit/autogen -Iutils/unlit/dist-install/build/unlit/autogen         -no-user-package-db -rtsopts       -Wnoncanonical-monad-instances  -odir utils/unlit/dist-install/build -hidir utils/unlit/dist-install/build -stubdir utils/unlit/dist-install/build     -fPIC -dynamic  -H32m -O -Wall       -i -iutils/unlit/. -iutils/unlit/dist-install/build -Iutils/unlit/dist-install/build -iutils/unlit/dist-install/build/unlit/autogen -Iutils/unlit/dist-install/build/unlit/autogen         -no-user-package-db -rtsopts       -Wnoncanonical-monad-instances  -fno-use-rpaths  -optl-Wl,-zorigin -no-auto-link-packages -no-hs-main  utils/unlit/dist-install/build/unlit.dyn_o
Warning: -rtsopts and -with-rtsopts have no effect with -no-hs-main.
    Call hs_init_ghc() from your main() function to set these options.
"/nix/store/f6xdg9gbi6s4ydqwz19v5hjmcy7x3gmz-ghc-8.2.2-binary/bin/ghc" -o utils/hp2ps/dist/build/tmp/hp2ps -hisuf hi -osuf  o -hcsuf hc -static  -H32m -O -Wall   -package-db libraries/bootstrapping.conf   -i -iutils/hp2ps/. -iutils/hp2ps/dist/build -Iutils/hp2ps/dist/build -iutils/hp2ps/dist/build/hp2ps/autogen -Iutils/hp2ps/dist/build/hp2ps/autogen         -no-user-package-db -rtsopts        -odir utils/hp2ps/dist/build -hidir utils/hp2ps/dist/build -stubdir utils/hp2ps/dist/build     -static  -H32m -O -Wall   -package-db libraries/bootstrapping.conf   -i -iutils/hp2ps/. -iutils/hp2ps/dist/build -Iutils/hp2ps/dist/build -iutils/hp2ps/dist/build/hp2ps/autogen -Iutils/hp2ps/dist/build/hp2ps/autogen         -no-user-package-db -rtsopts        -no-auto-link-packages -no-hs-main  utils/hp2ps/dist/build/AreaBelow.o utils/hp2ps/dist/build/Curves.o utils/hp2ps/dist/build/Error.o utils/hp2ps/dist/build/Main.o utils/hp2ps/dist/build/Reorder.o utils/hp2ps/dist/build/TopTwenty.o utils/hp2ps/dist/build/AuxFile.o utils/hp2ps/dist/build/Deviation.o utils/hp2ps/dist/build/HpFile.o utils/hp2ps/dist/build/Marks.o utils/hp2ps/dist/build/Scale.o utils/hp2ps/dist/build/TraceElement.o utils/hp2ps/dist/build/Axes.o utils/hp2ps/dist/build/Dimensions.o utils/hp2ps/dist/build/Key.o utils/hp2ps/dist/build/PsFile.o utils/hp2ps/dist/build/Shade.o utils/hp2ps/dist/build/Utilities.o   -lm
Warning: -rtsopts and -with-rtsopts have no effect with -no-hs-main.
    Call hs_init_ghc() from your main() function to set these options.
"inplace/bin/ghc-stage1" -o utils/hp2ps/dist-install/build/tmp/hp2ps -hisuf dyn_hi -osuf  dyn_o -hcsuf dyn_hc -fPIC -dynamic  -H32m -O -Wall       -i -iutils/hp2ps/. -iutils/hp2ps/dist-install/build -Iutils/hp2ps/dist-install/build -iutils/hp2ps/dist-install/build/hp2ps/autogen -Iutils/hp2ps/dist-install/build/hp2ps/autogen         -no-user-package-db -rtsopts       -Wnoncanonical-monad-instances  -odir utils/hp2ps/dist-install/build -hidir utils/hp2ps/dist-install/build -stubdir utils/hp2ps/dist-install/build     -fPIC -dynamic  -H32m -O -Wall       -i -iutils/hp2ps/. -iutils/hp2ps/dist-install/build -Iutils/hp2ps/dist-install/build -iutils/hp2ps/dist-install/build/hp2ps/autogen -Iutils/hp2ps/dist-install/build/hp2ps/autogen         -no-user-package-db -rtsopts       -Wnoncanonical-monad-instances  -fno-use-rpaths  -optl-Wl,-zorigin -no-auto-link-packages -no-hs-main  utils/hp2ps/dist-install/build/AreaBelow.dyn_o utils/hp2ps/dist-install/build/Curves.dyn_o utils/hp2ps/dist-install/build/Error.dyn_o utils/hp2ps/dist-install/build/Main.dyn_o utils/hp2ps/dist-install/build/Reorder.dyn_o utils/hp2ps/dist-install/build/TopTwenty.dyn_o utils/hp2ps/dist-install/build/AuxFile.dyn_o utils/hp2ps/dist-install/build/Deviation.dyn_o utils/hp2ps/dist-install/build/HpFile.dyn_o utils/hp2ps/dist-install/build/Marks.dyn_o utils/hp2ps/dist-install/build/Scale.dyn_o utils/hp2ps/dist-install/build/TraceElement.dyn_o utils/hp2ps/dist-install/build/Axes.dyn_o utils/hp2ps/dist-install/build/Dimensions.dyn_o utils/hp2ps/dist-install/build/Key.dyn_o utils/hp2ps/dist-install/build/PsFile.dyn_o utils/hp2ps/dist-install/build/Shade.dyn_o utils/hp2ps/dist-install/build/Utilities.dyn_o   -lm
Warning: -rtsopts and -with-rtsopts have no effect with -no-hs-main.
    Call hs_init_ghc() from your main() function to set these options.
"inplace/bin/ghc-stage1" -optc-fno-stack-protector -optc-Wall -optc-Wall -optc-Wextra -optc-Wstrict-prototypes -optc-Wmissing-prototypes -optc-Wmissing-declarations -optc-Winline -optc-Waggregate-return -optc-Wpointer-arith -optc-Wmissing-noreturn -optc-Wnested-externs -optc-Wredundant-decls -optc-Wundef -optc-Iincludes -optc-Iincludes/dist -optc-Iincludes/dist-derivedconstants/header -optc-Iincludes/dist-ghcconstants/header -optc-Irts -optc-Irts/dist/build -optc-DCOMPILING_RTS -optc-fno-strict-aliasing -optc-fno-common -optc-Irts/dist/build/./autogen -optc-Werror=unused-but-set-variable -optc-Wno-error=inline -optc-O2 -optc-fomit-frame-pointer -optc-g -optc-DRtsWay=\"rts_v\" -optc-ffunction-sections -optc-fdata-sections -static  -H32m -O -Wall   -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -dcmm-lint      -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen            -O2 -Wcpp-undef    -Wnoncanonical-monad-instances  -c rts/hooks/StackOverflow.c -o rts/dist/build/hooks/StackOverflow.o

Extension error:
The 'ghc-flag' directive is already registered to domain std

Extension error:
The 'ghc-flag' directive is already registered to domain std
make[1]: *** [docs/users_guide/ghc.mk:16: docs/users_guide/build-html/users_guide/index.html] Error 2
make[1]: *** Waiting for unfinished jobs....
make[1]: *** [docs/users_guide/ghc.mk:28: docs/users_guide/build-man/ghc.1] Error 2
make: *** [Makefile:127: all] Error 2
builder for '/nix/store/hc37mvicvrpaxibnwis4b9ah218wazqb-ghc-8.4.4.drv' failed with exit code 2
cannot build derivation '/nix/store/650asmf250zdywz3h1q3gz2r780cyr3w-parallel-julia-0.1.0.0.drv': 1 dependencies couldn't be built
error: build of '/nix/store/650asmf250zdywz3h1q3gz2r780cyr3w-parallel-julia-0.1.0.0.drv' failed