devenv: fix locale warnings, install shell completions, and more (#367567)

pkgs/by-name/de/devenv/package.nix

@@ -1,16 +1,16 @@
 {
   lib,
-  stdenv,
   fetchFromGitHub,
-  makeWrapper,
+  makeBinaryWrapper,
+  installShellFiles,
   rustPlatform,
   testers,
   cachix,
-  darwin,
   sqlx-cli,
   nixVersions,
   openssl,
   pkg-config,
+  glibcLocalesUtf8,
   devenv, # required to run version test
 }:
 
@@ -55,20 +55,41 @@ rustPlatform.buildRustPackage {
   '';
 
   nativeBuildInputs = [
-    makeWrapper
+    installShellFiles
+    makeBinaryWrapper
     pkg-config
     sqlx-cli
   ];
 
-  buildInputs =
-    [ openssl ]
-    ++ lib.optionals stdenv.hostPlatform.isDarwin [
-      darwin.apple_sdk.frameworks.SystemConfiguration
-    ];
+  buildInputs = [ openssl ];
 
-  postInstall = ''
-    wrapProgram $out/bin/devenv --set DEVENV_NIX ${devenv_nix} --prefix PATH ":" "$out/bin:${cachix}/bin"
-  '';
+  postInstall =
+    let
+      setDefaultLocaleArchive = lib.optionalString (glibcLocalesUtf8 != null) ''
+        --set-default LOCALE_ARCHIVE ${glibcLocalesUtf8}/lib/locale/locale-archive
+      '';
+    in
+    ''
+      wrapProgram $out/bin/devenv \
+        --prefix PATH ":" "$out/bin:${cachix}/bin" \
+        --set DEVENV_NIX ${devenv_nix} \
+        ${setDefaultLocaleArchive}
+
+      # Generate manpages
+      cargo xtask generate-manpages --out-dir man
+      installManPage man/*
+
+      # Generate shell completions
+      compdir=./completions
+      for shell in bash fish zsh; do
+        cargo xtask generate-shell-completion $shell --out-dir $compdir
+      done
+
+      installShellCompletion --cmd devenv \
+        --bash $compdir/devenv.bash \
+        --fish $compdir/devenv.fish \
+        --zsh $compdir/_devenv
+    '';
 
   passthru.tests = {
     version = testers.testVersion {