just: fix cross-compilation (#351032)

pkgs/by-name/ju/just/package.nix

@@ -9,16 +9,25 @@
   libiconv,
   mdbook,
   nix-update-script,
+  # run the compiled `just` to build the completions
+  installShellCompletions ? stdenv.buildPlatform.canExecute stdenv.hostPlatform,
+  # run the compiled `just` to build the man pages
+  installManPages ? stdenv.buildPlatform.canExecute stdenv.hostPlatform,
+  # run the compiled `generate-book` utility to prepare the files for mdbook
+  withDocumentation ? stdenv.buildPlatform.canExecute stdenv.hostPlatform,
 }:
 
 rustPlatform.buildRustPackage rec {
   pname = "just";
   version = "1.38.0";
-  outputs = [
-    "out"
-    "man"
-    "doc"
-  ];
+  outputs =
+    [
+      "out"
+    ]
+    ++ lib.optionals installManPages [
+      "man"
+    ]
+    ++ lib.optionals withDocumentation [ "doc" ];
 
   src = fetchFromGitHub {
     owner = "casey";
@@ -29,10 +38,9 @@ rustPlatform.buildRustPackage rec {
 
   cargoHash = "sha256-JHLkjMy5b1spJrAqFCCzqgnlYTAKA1Z9Tx4w1WWuiAI=";
 
-  nativeBuildInputs = [
-    installShellFiles
-    mdbook
-  ];
+  nativeBuildInputs =
+    lib.optionals (installShellCompletions || installManPages) [ installShellFiles ]
+    ++ lib.optionals withDocumentation [ mdbook ];
   buildInputs = lib.optionals stdenv.hostPlatform.isDarwin [ libiconv ];
 
   preCheck = ''
@@ -61,22 +69,9 @@ rustPlatform.buildRustPackage rec {
     ./fix-just-path-in-tests.patch
   ];
 
-  postBuild = ''
-    cargo run --package generate-book
-
-    mkdir -p completions man
-
-    cargo run -- --man > man/just.1
-
-    for shell in bash fish zsh; do
-        cargo run -- --completions $shell > completions/just.$shell
-    done
-
-    # No linkcheck in sandbox
-    echo 'optional = true' >> book/en/book.toml
-    mdbook build book/en
-    find .
-  '';
+  cargoBuildFlags = [
+    "--package=just"
+  ] ++ (lib.optionals withDocumentation [ "--package=generate-book" ]);
 
   checkFlags = [
     "--skip=backticks::trailing_newlines_are_stripped" # Wants to use python3 as alternate shell
@@ -87,16 +82,26 @@ rustPlatform.buildRustPackage rec {
     "--skip=shebang::run_shebang" # test case very rarely fails with "Text file busy"
   ];
 
-  postInstall = ''
-    mkdir -p $doc/share/doc/$name
-    mv ./book/en/build/html $doc/share/doc/$name
-    installManPage man/just.1
-
-    installShellCompletion --cmd just \
-      --bash completions/just.bash \
-      --fish completions/just.fish \
-      --zsh completions/just.zsh
-  '';
+  postInstall =
+    lib.optionalString withDocumentation ''
+      $out/bin/generate-book
+      rm $out/bin/generate-book
+      # No linkcheck in sandbox
+      echo 'optional = true' >> book/en/book.toml
+      mdbook build book/en
+      mkdir -p $doc/share/doc/$name
+      mv ./book/en/build/html $doc/share/doc/$name
+    ''
+    + lib.optionalString installManPages ''
+      $out/bin/just --man > ./just.1
+      installManPage ./just.1
+    ''
+    + lib.optionalString installShellCompletions ''
+      installShellCompletion --cmd just \
+        --bash <($out/bin/just --completions bash) \
+        --fish <($out/bin/just --completions fish) \
+        --zsh <($out/bin/just --completions zsh)
+    '';
 
   setupHook = ./setup-hook.sh;