[WIP] Start fix of --experimental_use_sandboxfs

[smelc]

Fixes #1265

This draft PR starts implementing the solution drafted by @aherrmann in #1265 (comment) to make --experimental_use_sandboxfs work when using bindists (no NixOS, no nix-shell context). Let me record that the intended setup to test this PR is described here.

It fixes the issue that executables - within ghc's install bin directory - need content in the sibling lib directory. Because this content is not tracked precisely right now, it is missing when executing within sandboxfs with --experimental_use_sandboxfs (see bazel+sandboxfs usage).

The first commit fixes failures of the form ../lib/path being missing. I made a checkpoint here because with this commit, bazel test //tests/... now fails in a different manner:

  File "bazel-out/host/bin/haskell/cc_wrapper-python", line 111, in FindModuleSpace
    raise AssertionError('Cannot find .runfiles directory for %s' % sys.argv[0])
AssertionError: Cannot find .runfiles directory for bazel-out/host/bin/haskell/cc_wrapper-python
compiling bazel-out/k8-fastbuild/bin/tests/library-with-cbits/_hsc/library-with-cbits-static/AddOne_hsc_make.c failed (exit code 1)
command was: bazel-out/host/bin/haskell/cc_wrapper-python -c bazel-out/k8-fastbuild/bin/tests/library-with-cbits/_hsc/library-with-cbits-static/AddOne_hsc_make.c -o bazel-out/k8-fastbuild/bin/tests/library-with-cbits/_hsc/library-with-cbits-static/AddOne_hsc_make.o -fno-stack-protector -iquote . -iquote bazel-out/k8-fastbuild/bin -U_FORTIFY_SOURCE -fstack-protector -Wall -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer -fno-canonical-system-headers -Wno-builtin-macro-redefined -D__DATE__="redacted" -D__TIMESTAMP__="redacted" -D__TIME__="redacted" -Iexternal/rules_haskell_ghc_linux_amd64/bin/../lib/include/

And here's one specific failure when running bazel test --experimental_use_sandboxfs --sandbox_debug //tests/cc_haskell_import/...:

ERROR: /media/crypt1/repos/rules_haskell/rules_haskell_1265_alt/tests/cc_haskell_import/BUILD.bazel:19:1: HaskellBuildLibrary //tests/cc_haskell_import:hs-lib-b failed (Exit 1) linux-sandbox failed: error executing command 
  (cd /home/churlin/.cache/bazel/_bazel_churlin/31b8c33fa4dcf9eee06a0a8329314f3e/sandbox/sandboxfs/75 && \
  exec env - \
    LANG=C.UTF-8 \
    TMPDIR=/tmp \
  /home/churlin/.cache/bazel/_bazel_churlin/install/d687aca87a7669724cc958527f2423da/linux-sandbox -t 15 -w /home/churlin/.cache/bazel/_bazel_churlin/31b8c33fa4dcf9eee06a0a8329314f3e/sandbox/linux-sandbox/80/execroot/rules_haskell -w /tmp -w /dev/shm -D -- bazel-out/host/bin/haskell/ghc_wrapper bazel-out/k8-fastbuild/bin/tests/cc_haskell_import/compile_flags_hs-lib-b_HaskellBuildLibrary bazel-out/k8-fastbuild/bin/tests/cc_haskell_import/extra_args_hs-lib-b_HaskellBuildLibrary)
...
tests/cc_haskell_import/LibB_stub.h: openFile: permission denied (Permission denied)

[aherrmann]

Note, you can use ctx.files.full_ghc as a short-cut.

[aherrmann]

The first commit fixes failures of the form ../lib/path being missing. I made a checkpoint here because with this commit, bazel test //tests/... now fails in a different manner:

  File "bazel-out/host/bin/haskell/cc_wrapper-python", line 111, in FindModuleSpace
    raise AssertionError('Cannot find .runfiles directory for %s' % sys.argv[0])
AssertionError: Cannot find .runfiles directory for bazel-out/host/bin/haskell/cc_wrapper-python
compiling bazel-out/k8-fastbuild/bin/tests/library-with-cbits/_hsc/library-with-cbits-static/AddOne_hsc_make.c failed (exit code 1)
command was: bazel-out/host/bin/haskell/cc_wrapper-python -c bazel-out/k8-fastbuild/bin/tests

That's interesting. This indicates that the cc_wrapper's runfiles are not included in the sandbox. If you haven't, yet, I recommend reading the runfiles guide to get a good understanding of them.

[smelc]

Closing request as it's not planned for me to have time allocated to continue this work in the near future.