Expose mir-borrowck via a query.

(A followup commit removes the mir::transform based entry point.)

Author: pnkfelix

src/librustc/dep_graph/dep_node.rs

@@ -411,6 +411,8 @@ define_dep_nodes!( <'tcx>
 
     [] BorrowCheckKrate,
     [] BorrowCheck(DefId),
+    [] MirBorrowCheck(DefId),
+
     [] RvalueCheck(DefId),
     [] Reachability,
     [] MirKeys,

src/librustc/ty/maps.rs

@@ -923,6 +923,8 @@ define_maps! { <'tcx>
     [] coherent_trait: coherent_trait_dep_node((CrateNum, DefId)) -> (),
 
     [] borrowck: BorrowCheck(DefId) -> (),
+    // FIXME: shouldn't this return a `Result<(), BorrowckErrors>` instead?
+    [] mir_borrowck: MirBorrowCheck(DefId) -> (),
 
     /// Gets a complete map from all types to their inherent impls.
     /// Not meant to be used directly outside of coherence.

src/librustc_driver/driver.rs

@@ -1075,6 +1075,10 @@ pub fn phase_3_run_analysis_passes<'tcx, F, R>(sess: &'tcx Session,
              "borrow checking",
              || borrowck::check_crate(tcx));
 
+        time(time_passes,
+             "MIR borrow checking",
+             || for def_id in tcx.body_owners() { tcx.mir_borrowck(def_id) });
+
         // Avoid overwhelming user with errors if type checking failed.
         // I'm not sure how helpful this is, to be honest, but it avoids
         // a

src/librustc_mir/borrow_check.rs

@@ -0,0 +1,31 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use rustc::hir::def_id::{DefId};
+use rustc::mir::transform::{MirSource};
+use rustc::ty::{TyCtxt};
+use rustc::ty::maps::Providers;
+
+pub fn provide(providers: &mut Providers) {
+    *providers = Providers {
+        mir_borrowck,
+        ..*providers
+    };
+}
+
+fn mir_borrowck<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) {
+    let mir = tcx.mir_validated(def_id);
+    let src = MirSource::from_local_def_id(tcx, def_id);
+    debug!("run query mir_borrowck: {}", tcx.node_path_str(src.item_id()));
+
+    if tcx.has_attr(def_id, "rustc_mir_borrowck") || tcx.sess.opts.debugging_opts.borrowck_mir {
+        ::transform::borrow_check::borrowck_mir(tcx, src, &mir.borrow());
+    }
+}

src/librustc_mir/lib.rs

@@ -45,6 +45,7 @@ extern crate core; // for NonZero
 
 mod diagnostics;
 
+mod borrow_check;
 mod build;
 mod dataflow;
 mod hair;
@@ -55,6 +56,7 @@ pub mod util;
 use rustc::ty::maps::Providers;
 
 pub fn provide(providers: &mut Providers) {
+    borrow_check::provide(providers);
     shim::provide(providers);
     transform::provide(providers);
 }

src/librustc_mir/transform/borrow_check.rs

@@ -57,7 +57,7 @@ impl MirPass for BorrowckMir {
     }
 }
 
-fn borrowck_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, src: MirSource, mir: &Mir<'tcx>)
+pub(crate) fn borrowck_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, src: MirSource, mir: &Mir<'tcx>)
 {
     let id = src.item_id();
     let def_id = tcx.hir.local_def_id(id);

src/librustc_mir/transform/mod.rs

@@ -123,8 +123,9 @@ fn mir_validated<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx
 }
 
 fn optimized_mir<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx Mir<'tcx> {
-    // Borrowck uses `mir_validated`, so we have to force it to
+    // (Mir-)Borrowck uses `mir_validated`, so we have to force it to
     // execute before we can steal.
+    ty::queries::mir_borrowck::force(tcx, DUMMY_SP, def_id);
     ty::queries::borrowck::force(tcx, DUMMY_SP, def_id);
 
     let mut mir = tcx.mir_validated(def_id).steal();