all-in-one: merge entrypoint into the devshell dir (#121)

Split the entrypoint and env.bash. This makes it easier to expose the
buildEnv.

.envrc

@@ -14,4 +14,4 @@ nix-build shell.nix --out-link "$out_link"
 
 # Load the devshell
 # shellcheck disable=SC1090
-source "$out_link"
+source "$out_link/env.bash"

.github/workflows/nix.yml

@@ -18,7 +18,8 @@ jobs:
         with:
           name: numtide
           authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-      - run: $(nix-build shell.nix) --pure /usr/bin/env HOME=$HOME bash -c "cd devshell && golangci-lint run"
+      - run: |
+          $(./shell.nix)/entrypoint --pure /usr/bin/env HOME=$HOME bash -c "cd devshell && golangci-lint run"
       - run: nix-shell --run "echo OK"
       - run: nix-build
   flakes:

modules/devshell.nix

@@ -22,7 +22,7 @@ let
     pkgs.stdenvNoCC.mkDerivation {
       name = "devshell-setup-hook";
       setupHook = pkgs.writeText "devshell-setup-hook.sh" ''
-        source ${entrypoint}
+        source ${devshell_dir}/env.bash
       '';
       dontUnpack = true;
       dontBuild = true;
@@ -58,8 +58,11 @@ let
 
   # Write a bash profile to load
   envBash = pkgs.writeText "devshell-env.bash" ''
+    # It assums that the shell is always loaded from the root of the project.
+    export DEVSHELL_ROOT=''${DEVSHELL_ROOT:-$PWD}
+
     # Expose the folder that contains the assembled environment.
-    export DEVSHELL_DIR=@devshellDir@
+    export DEVSHELL_DIR=@DEVSHELL_DIR@
 
     # Prepend the PATH with the devshell dir and bash
     PATH=''${PATH%:/path-not-set}
@@ -78,29 +81,18 @@ let
     fi # Interactive session
   '';
 
-  # Builds the DEVSHELL_DIR with all the dependencies
-  devshellDir = pkgs.buildEnv {
-    name = "devshell-dir";
-    paths = cfg.packages;
-    postBuild = ''
-      cp ${envBash} $out/env.bash
-      substituteInPlace $out/env.bash --subst-var-by devshellDir $out
-    '';
-  };
 
-  # This is our entry-point for everything!
+  # This is our entrypoint script.
   entrypoint = pkgs.writeShellScript "${cfg.name}-entrypoint" ''
     #!${bashPath}
     # Script that sets-up the environment. Can be both sourced or invoked.
 
-    # It assums that the shell is always loaded from the root of the project.
-    # Store that for later usage.
-    export DEVSHELL_ROOT=$PWD
+    export DEVSHELL_DIR=@DEVSHELL_DIR@
 
     # If the file is sourced, skip all of the rest and just source the env
     # script.
     if [[ $0 != "''${BASH_SOURCE[0]}" ]]; then
-      source "${devshellDir}/env.bash"
+      source "$DEVSHELL_DIR/env.bash"
       return
     fi
 
@@ -109,11 +101,10 @@ let
 
     if [[ $# = 0 ]]; then
       # Start an interactive shell
-      exec "${bashPath}" --rcfile "${devshellDir}/env.bash" --noprofile
+      exec "${bashPath}" --rcfile "$DEVSHELL_DIR/env.bash" --noprofile
     elif [[ $1 == "-h" || $1 == "--help" ]]; then
       cat <<USAGE
     Usage: ${cfg.name}
-      source $0               # load the environment in the current bash
       $0 -h | --help          # show this help
       $0 [--pure]             # start a bash sub-shell
       $0 [--pure] <cmd> [...] # run a command in the environment
@@ -128,10 +119,22 @@ let
       exec -c "$0" "$@"
     else
       # Start a script
-      source "${devshellDir}/env.bash"
+      source "$DEVSHELL_DIR/env.bash"
       exec -- "$@"
     fi
   '';
+
+  # Builds the DEVSHELL_DIR with all the dependencies
+  devshell_dir = pkgs.buildEnv {
+    name = "devshell-dir";
+    paths = cfg.packages;
+    postBuild = ''
+      substitute ${envBash} $out/env.bash --subst-var-by DEVSHELL_DIR $out
+      substitute ${entrypoint} $out/entrypoint --subst-var-by DEVSHELL_DIR $out
+      chmod +x $out/entrypoint
+    '';
+  };
+
 in
 {
   options.devshell = {
@@ -143,11 +146,11 @@ in
       description = "Version of bash to use in the project";
     };
 
-    entrypoint = mkOption {
+    package = mkOption {
       internal = true;
       type = types.package;
       description = ''
-        This package contains a script that loads the current environment.
+        This package contains the DEVSHELL_DIR
       '';
     };
 
@@ -220,7 +223,7 @@ in
   };
 
   config.devshell = {
-    entrypoint = entrypoint;
+    package = devshell_dir;
 
     startup = {
       load_profiles = noDepEntry ''
@@ -283,7 +286,7 @@ in
     # Use a naked derivation to limit the amount of noise passed to nix-shell.
     shell = mkNakedShell {
       name = cfg.name;
-      script = cfg.entrypoint;
+      profile = cfg.package;
       passthru = {
         inherit config;
         flakeApp = mkFlakeApp entrypoint;

nix/mkNakedShell.nix

@@ -20,8 +20,9 @@ let
   };
 in
 { name
-, # A path to a script that will be loaded by the shell
-  script
+, # A path to a buildEnv that will be loaded by the shell.
+  # We assume that the buildEnv contains an ./env.bash script.
+  profile
 , meta ? { }
 , passthru ? { }
 }:
@@ -32,7 +33,7 @@ in
   builder = bashPath;
 
   # Bring in the dependencies on `nix-build`
-  args = [ "-ec" "${coreutils}/bin/ln -s ${script} $out; exit 0" ];
+  args = [ "-ec" "${coreutils}/bin/ln -s ${profile} $out; exit 0" ];
 
   # $stdenv/setup is loaded by nix-shell during startup.
   # https://github.com/nixos/nix/blob/377345e26f1ac4bbc87bb21debcc52a1d03230aa/src/nix-build/nix-build.cc#L429-L432
@@ -53,7 +54,7 @@ in
       export SHELL=${bashPath}
     fi
 
-    # Load the script environment
-    source "${script}"
+    # Load the environment
+    source "${profile}/env.bash"
   '';
 }) // { inherit meta passthru; } // passthru

tests/core/commands.nix

@@ -31,7 +31,7 @@
     in
     runTest "devshell-1" { } ''
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
       menu
 

tests/core/devshell.nix

@@ -10,7 +10,7 @@
     in
     runTest "devshell-1" { } ''
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
       # Sets an environment variable that points to the buildEnv
       assert -n "$DEVSHELL_DIR"

tests/core/env.nix

@@ -25,7 +25,7 @@
       unset XDG_DATA_DIRS
 
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
       # NIXPKGS_PATH is being set
       assert "$NIXPKGS_PATH" == "${toString pkgs.path}"

tests/extra/git.hooks.nix

@@ -26,7 +26,7 @@
       assert_fail -L .git/hooks/pre-commit
 
       # Load the devshell
-      source ${shell1}
+      source ${shell1}/env.bash
 
       # The hook has been install
       assert -L .git/hooks/pre-commit
@@ -35,7 +35,7 @@
       assert "$(.git/hooks/pre-commit)" == "PRE-COMMIT"
 
       # Load the new config
-      source ${shell2}
+      source ${shell2}/env.bash
 
       # The hook should have been uninstalled
       assert_fail -L .git/hooks/pre-commit

tests/extra/language.c.nix

@@ -10,7 +10,7 @@
     in
     runTest "language-c-1" { } ''
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
 
       # Has a C compiler

tests/extra/language.rust.nix

@@ -10,7 +10,7 @@
     in
     runTest "simple" { } ''
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
       # Has a rust compiler
       type -p rustc

tests/extra/locale.nix

@@ -13,7 +13,7 @@
       assert -z "$LOCALE_ARCHIVE"
 
       # Load the devshell
-      source ${shell}
+      source ${shell}/env.bash
 
       # Sets LOCALE_ARCHIVE
       if [[ $OSTYPE == linux-gnu ]]; then