Support returning the modified PATH

[ndmitchell]

From https://github.com/digital-asset/ghcide/issues/294, if you stack install a package then any build tools (e.g. record-dot-preprocessor) seem to get put locally and added to the PATH locally by Stack. Maybe hie-bios needs to include that extra PATH information, so that tools building on it see the PATH too? Probably an additional field to ComponentOptions?

[fendor]

With recent stack versions, there is the command stack config env that prints the modified path. Could be useful for this!
Example output:

> stack config env
GHC_ENVIRONMENT='-'; export GHC_ENVIRONMENT;
GHC_PACKAGE_PATH='/home/baldr/Documents/haskell/fprog/.stack-work/install/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/pkgdb:/home/baldr/.stack/snapshots/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/pkgdb:/nix/store/hg3na12737n7wws1kndxvs95ai88fgn8-ghc-8.6.5/lib/ghc-8.6.5/package.conf.d'; export GHC_PACKAGE_PATH;
HASKELL_DIST_DIR='/home/baldr/Documents/haskell/fprog/.stack-work/dist/x86_64-linux-nix/Cabal-2.4.0.1'; export HASKELL_DIST_DIR;
HASKELL_PACKAGE_SANDBOX='/home/baldr/.stack/snapshots/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/pkgdb'; export HASKELL_PACKAGE_SANDBOX;
HASKELL_PACKAGE_SANDBOXES='/home/baldr/Documents/haskell/fprog/.stack-work/install/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/pkgdb:/home/baldr/.stack/snapshots/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/pkgdb:'; export HASKELL_PACKAGE_SANDBOXES;
PATH='/home/baldr/Documents/haskell/fprog/.stack-work/install/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/bin:/home/baldr/.stack/snapshots/x86_64-linux-nix/80444f540c4822726693e9a6f829471e2418b26f60fd37aa1ddd1f531fd9d952/8.6.5/bin:/home/baldr/.stack/compiler-tools/x86_64-linux-nix/ghc-8.6.5/bin:/nix/store/hg3na12737n7wws1kndxvs95ai88fgn8-ghc-8.6.5/bin:/nix/store/lb3hli8d9536g45mndwfwyi6fpny0blh-bash-interactive-4.4-p23/bin:/nix/store/2xwxj5qrrc71asdk1wyq19nz9k845pzs-patchelf-0.9/bin:/nix/store/hg3na12737n7wws1kndxvs95ai88fgn8-ghc-8.6.5/bin:/nix/store/291ldi6fqsbmkbvbs8is4mcg3jb64ld4-gcc-wrapper-8.3.0/bin:/nix/store/62x7m20m7lm8y8s17cbgha0sf3cmma19-gcc-8.3.0/bin:/nix/store/hblpx8x5w88igmwa4ydnsnb65s363lji-glibc-2.27-bin/bin:/nix/store/9v78r3afqy9xn9zwdj9wfys6sk3vc01d-coreutils-8.31/bin:/nix/store/gwwycf3w6cbj0gd2mpgblrdjc24f3cys-binutils-wrapper-2.31.1/bin:/nix/store/ajrrkivdfvp8dp4vdg5hp1h5hblmanc9-binutils-2.31.1/bin:/nix/store/hblpx8x5w88igmwa4ydnsnb65s363lji-glibc-2.27-bin/bin:/nix/store/9v78r3afqy9xn9zwdj9wfys6sk3vc01d-coreutils-8.31/bin:/nix/store/06q8j7z84zqjzcijvz90i4v7j5mfk4jl-git-2.23.1/bin:/nix/store/my5v4x1n5568vgziyc63vmc97nk8ril9-ncurses-6.1-20190112/bin:/nix/store/9v78r3afqy9xn9zwdj9wfys6sk3vc01d-coreutils-8.31/bin:/nix/store/0zdsw4qdrwi41mfdwqpxknsvk9fz3gkb-findutils-4.7.0/bin:/nix/store/dys98skw6ifw5qsqrhjxjjiydyfbg3nq-diffutils-3.7/bin:/nix/store/g2h4491kab7l06v9rf1lnyjvzdwy5ak0-gnused-4.7/bin:/nix/store/71y5ddyz8vmsw9wgi3gzifcls53r60i9-gnugrep-3.3/bin:/nix/store/84yafwjc6sga23vwsbahhymikjhfbnw4-gawk-5.0.1/bin:/nix/store/aawf0q16ql39w2gwv52qyjfzgbg5f22r-gnutar-1.32/bin:/nix/store/afyqk8219zfv5and3pqahzvn6bpmx3dq-gzip-1.10/bin:/nix/store/iws7dm1jij4lv09mbpwf9i8lc1d4b798-bzip2-1.0.6.0.1-bin/bin:/nix/store/j8fq1ksp37w88rx80blzazldi17f3x7s-gnumake-4.2.1/bin:/nix/store/rm1hz1lybxangc8sdl7xvzs5dcvigvf7-bash-4.4-p23/bin:/nix/store/lmi2nqb1cfzr3ps2zkq97q88zzkhp4mj-patch-2.7.6/bin:/nix/store/y04xj2mbc66zs53fackn1wwlrv31bv3y-xz-5.2.4-bin/bin'; export PATH;
STACK_EXE='/nix/store/8h0dkdjxjdrnvwsp8l0wp9infn9j010l-stack-2.1.3.1/bin/stack'; export STACK_EXE;

[wz1000]

Can't we read PATH from the environment in the cabal wrapper program?

[fendor]

Indeed.

EDIT: I got sidetracked and forgot what I wanted to write and apparently pressed send by accident.