Auto merge of #40347 - alexcrichton:rm-liblog, r=brson

Remove internal liblog

This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.

The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:

    #![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
    #![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]

This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:

* Mark themselves as entirely unstable via the `staged_api` feature and the
  `#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
  required if the crate relies on any other crates to compile (other than std).

3 files changed, 6 insertions, 3 deletions

diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index caa5c8b7e00..5b5113caa8e 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -11,7 +11,8 @@ crate-type = ["dylib"]
 [dependencies]
 arena = { path = "../libarena" }
 graphviz = { path = "../libgraphviz" }
-log = { path = "../liblog" }
+log = { version = "0.3", features = ["release_max_level_info"] }
+env_logger = { version = "0.4", default-features = false }
 proc_macro_plugin = { path = "../libproc_macro_plugin" }
 rustc = { path = "../librustc" }
 rustc_back = { path = "../librustc_back" }
diff --git a/src/librustc_driver/driver.rs b/src/librustc_driver/driver.rs
index d37553d7d66..81095ad9f83 100644
--- a/src/librustc_driver/driver.rs
+++ b/src/librustc_driver/driver.rs
@@ -198,13 +198,13 @@ pub fn compile_input(sess: &Session,
 
             result?;
 
-            if log_enabled!(::log::INFO) {
+            if log_enabled!(::log::LogLevel::Info) {
                 println!("Pre-trans");
                 tcx.print_debug_stats();
             }
             let trans = phase_4_translate_to_llvm(tcx, analysis, &incremental_hashes_map);
 
-            if log_enabled!(::log::INFO) {
+            if log_enabled!(::log::LogLevel::Info) {
                 println!("Post-trans");
                 tcx.print_debug_stats();
             }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 62d75126557..68b9f85721a 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -35,6 +35,7 @@
 extern crate arena;
 extern crate getopts;
 extern crate graphviz;
+extern crate env_logger;
 extern crate libc;
 extern crate rustc;
 extern crate rustc_back;
@@ -1127,6 +1128,7 @@ pub fn diagnostics_registry() -> errors::registry::Registry {
 }
 
 pub fn main() {
+    env_logger::init().unwrap();
     let result = run(|| run_compiler(&env::args().collect::<Vec<_>>(),
                                      &mut RustcDefaultCalls,
                                      None,