tools: add bash completion for node

This commit adds a --completion-bash option to node which can be
sourced to provide bash code completion for node options.

Usage:
$ node --completion-bash  > node_bash_completion
$ source node_bash_completion
$ node --[tab]

doc/api/cli.md

@@ -52,6 +52,17 @@ If this flag is passed, the behavior can still be set to not abort through
 [`process.setUncaughtExceptionCaptureCallback()`][] (and through usage of the
 `domain` module that uses it).
 
+### `--completion-bash`
+<!-- YAML
+added: REPLACEME
+-->
+
+Print source-able bash completion script for Node.js.
+```console
+$ node --completion-bash > node_bash_completion
+$ source node_bash_completion
+```
+
 ### `--enable-fips`
 <!-- YAML
 added: v6.0.0

doc/node.1

@@ -75,6 +75,9 @@ the next argument will be used as a script filename.
 .It Fl -abort-on-uncaught-exception
 Aborting instead of exiting causes a core file to be generated for analysis.
 .
+.It Fl -completion-bash
+Print source-able bash completion script for Node.js.
+.
 .It Fl -enable-fips
 Enable FIPS-compliant crypto at startup.
 Requires Node.js to be built with

lib/internal/bash_completion.js

@@ -0,0 +1,25 @@
+'use strict';
+const { internalBinding } = require('internal/bootstrap/loaders');
+const { getOptions } = internalBinding('options');
+
+function print(stream) {
+  const { options, aliases } = getOptions();
+  const all_opts = [...options.keys(), ...aliases.keys()];
+
+  stream.write(`_node_complete() {
+  local cur_word options
+  cur_word="\${COMP_WORDS[COMP_CWORD]}"
+  if [[ "\${cur_word}" == -* ]] ; then
+    COMPREPLY=( $(compgen -W '${all_opts.join(' ')}' -- "\${cur_word}") )
+    return 0
+  else
+    COMPREPLY=( $(compgen -f "\${cur_word}") )
+    return 0
+  fi
+}
+complete -F _node_complete node node_g`);
+}
+
+module.exports = {
+  print
+};

lib/internal/bootstrap/node.js

@@ -111,11 +111,17 @@
       NativeModule.require('internal/inspector_async_hook').setup();
     }
 
-    if (internalBinding('options').getOptions('--help')) {
+    const options = internalBinding('options');
+    if (options.getOptions('--help')) {
       NativeModule.require('internal/print_help').print(process.stdout);
       return;
     }
 
+    if (options.getOptions('--completion-bash')) {
+      NativeModule.require('internal/bash_completion').print(process.stdout);
+      return;
+    }
+
     if (isMainThread) {
       mainThreadSetup.setupChildProcessIpcChannel();
     }

node.gyp

@@ -84,6 +84,7 @@
       'lib/zlib.js',
       'lib/internal/assert.js',
       'lib/internal/async_hooks.js',
+      'lib/internal/bash_completion.js',
       'lib/internal/buffer.js',
       'lib/internal/cli_table.js',
       'lib/internal/child_process.js',

src/node_options.cc

@@ -221,6 +221,9 @@ PerProcessOptionsParser::PerProcessOptionsParser() {
             kAllowedInEnvironment);
 
   AddOption("--security-reverts", "", &PerProcessOptions::security_reverts);
+  AddOption("--completion-bash",
+            "print source-able bash completion script",
+            &PerProcessOptions::print_bash_completion);
   AddOption("--help",
             "print node command line options",
             &PerProcessOptions::print_help);

src/node_options.h

@@ -112,6 +112,7 @@ class PerProcessOptions {
   bool zero_fill_all_buffers = false;
 
   std::vector<std::string> security_reverts;
+  bool print_bash_completion = false;
   bool print_help = false;
   bool print_v8_help = false;
   bool print_version = false;