Auto merge of #11262 - campaul:add_version_flag, r=Manishearth

Add `--version` flag

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy --faster` does not report any errors
- [X] These changes fix #11241 (github issue number if applicable).

Either:
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

Not 100% sure of a good way to test this, so I'm submitting as is for feedback. Manually testing it appears to work fine.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="35" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/11262)
<!-- Reviewable:end -->

3 files changed, 30 insertions, 0 deletions

diff --git a/components/servo/main.rs b/components/servo/main.rs
index bf4c0b14f4c..ca0eec17955 100644
--- a/components/servo/main.rs
+++ b/components/servo/main.rs
@@ -40,6 +40,7 @@ use servo::Browser;
 use servo::compositing::windowing::WindowEvent;
 use servo::util::opts::{self, ArgumentParsingResult};
 use servo::util::panicking::initiate_panic_hook;
+use std::process;
 use std::rc::Rc;
 
 pub mod platform {
@@ -102,6 +103,11 @@ fn main() {
         return servo::run_content_process(token)
     }
 
+    if opts::get().is_printing_version {
+        println!("Servo {}{}", env!("CARGO_PKG_VERSION"), env!("GIT_INFO"));
+        process::exit(0);
+    }
+
     let window = app::create_window(None);
 
     // Our wrapper around `Browser` that also implements some
diff --git a/components/util/opts.rs b/components/util/opts.rs
index 711782ab3ea..1fe76f96d26 100644
--- a/components/util/opts.rs
+++ b/components/util/opts.rs
@@ -202,6 +202,9 @@ pub struct Opts {
 
     // don't skip any backtraces on panic
     pub full_backtraces: bool,
+
+    /// Print the version and exit.
+    pub is_printing_version: bool,
 }
 
 fn print_usage(app: &str, opts: &Options) {
@@ -507,6 +510,7 @@ pub fn default_opts() -> Opts {
         render_api: DEFAULT_RENDER_API,
         config_dir: None,
         full_backtraces: false,
+        is_printing_version: false,
     }
 }
 
@@ -564,6 +568,7 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
     opts.optopt("G", "graphics", "Select graphics backend (gl or es2)", "gl");
     opts.optopt("", "config-dir",
                     "config directory following xdg spec on linux platform", "");
+    opts.optflag("v", "version", "Display servo version information");
 
 
     let opt_match = match opts.parse(args) {
@@ -753,6 +758,8 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         _ => args_fail(&format!("error: graphics option must be gl or es2:")),
     };
 
+    let is_printing_version = opt_match.opt_present("v") || opt_match.opt_present("version");
+
     let opts = Opts {
         is_running_problem_test: is_running_problem_test,
         url: Some(url),
@@ -807,6 +814,7 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         use_msaa: debug_options.use_msaa,
         config_dir: opt_match.opt_str("config-dir"),
         full_backtraces: debug_options.full_backtraces,
+        is_printing_version: is_printing_version,
     };
 
     set_defaults(opts);
diff --git a/python/servo/command_base.py b/python/servo/command_base.py
index e90245f43ec..990bc9a586c 100644
--- a/python/servo/command_base.py
+++ b/python/servo/command_base.py
@@ -374,6 +374,22 @@ class CommandBase(object):
 
         env['RUSTFLAGS'] = env.get('RUSTFLAGS', "") + " -W unused-extern-crates"
 
+        git_info = []
+        if os.path.isdir('.git'):
+            git_sha = subprocess.check_output([
+                'git', 'rev-parse', '--short', 'HEAD'
+            ]).strip()
+            git_is_dirty = bool(subprocess.check_output([
+                'git', 'status', '--porcelain'
+            ]).strip())
+
+            git_info.append('')
+            git_info.append(git_sha)
+            if git_is_dirty:
+                git_info.append('dirty')
+
+        env['GIT_INFO'] = '-'.join(git_info)
+
         return env
 
     def servo_crate(self):