Auto merge of rust-lang#21876 - nick29581:driver-args, r=huonw

This allows people to write tools which are drop-in replacements for rustc by implementing `CompilerCalls` and three lines of code, rather than having to copy+paste a bunch of args parsing code.

r? @alexcrichton

Author: bors

src/librustc/session/config.rs

@@ -33,9 +33,10 @@ use syntax::diagnostic::{ColorConfig, Auto, Always, Never, SpanHandler};
 use syntax::parse;
 use syntax::parse::token::InternedString;
 
+use getopts;
 use std::collections::HashMap;
 use std::collections::hash_map::Entry::{Occupied, Vacant};
-use getopts;
+use std::env;
 use std::fmt;
 
 use llvm;
@@ -821,7 +822,6 @@ pub fn parse_cfgspecs(cfgspecs: Vec<String> ) -> ast::CrateConfig {
 }
 
 pub fn build_session_options(matches: &getopts::Matches) -> Options {
-
     let unparsed_crate_types = matches.opt_strs("crate-type");
     let crate_types = parse_crate_types_from_list(unparsed_crate_types)
         .unwrap_or_else(|e| early_error(&e[]));
@@ -1041,7 +1041,22 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         crate_name: crate_name,
         alt_std_name: None,
         libs: libs,
-        unstable_features: UnstableFeatures::Disallow
+        unstable_features: get_unstable_features_setting(),
+    }
+}
+
+pub fn get_unstable_features_setting() -> UnstableFeatures {
+    // Whether this is a feature-staged build, i.e. on the beta or stable channel
+    let disable_unstable_features = option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some();
+    // The secret key needed to get through the rustc build itself by
+    // subverting the unstable features lints
+    let bootstrap_secret_key = option_env!("CFG_BOOTSTRAP_KEY");
+    // The matching key to the above, only known by the build system
+    let bootstrap_provided_key = env::var_string("RUSTC_BOOTSTRAP_KEY").ok();
+    match (disable_unstable_features, bootstrap_secret_key, bootstrap_provided_key) {
+        (_, Some(ref s), Some(ref p)) if s == p => UnstableFeatures::Cheat,
+        (true, _, _) => UnstableFeatures::Disallow,
+        (false, _, _) => UnstableFeatures::Default
     }
 }
 

src/librustc_driver/driver.rs

@@ -1,4 +1,4 @@
-// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -27,6 +27,7 @@ use rustc_trans::back::write;
 use rustc_trans::trans;
 use rustc_typeck as typeck;
 use rustc_privacy;
+use super::Compilation;
 
 use serialize::json;
 
@@ -55,7 +56,7 @@ pub fn compile_input(sess: Session,
             let state = $make_state;
             (control.$point.callback)(state);
         }
-        if control.$point.stop {
+        if control.$point.stop == Compilation::Stop {
             return;
         }
     })}
@@ -206,14 +207,14 @@ impl<'a> CompileController<'a> {
 }
 
 pub struct PhaseController<'a> {
-    pub stop: bool,
+    pub stop: Compilation,
     pub callback: Box<Fn(CompileState) -> () + 'a>,
 }
 
 impl<'a> PhaseController<'a> {
     pub fn basic() -> PhaseController<'a> {
         PhaseController {
-            stop: false,
+            stop: Compilation::Continue,
             callback: box |_| {},
         }
     }