Disable certain code on nll runs, update constraint generation to fix bugs, and update tests based on feedback

Author: Nashenas88

src/librustc_mir/borrow_check/mod.rs

@@ -81,11 +81,13 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
     // contain non-lexical lifetimes. It will have a lifetime tied
     // to the inference context.
     let mut mir: Mir<'tcx> = input_mir.clone();
-    let free_regions = {
+    let free_regions = if !tcx.sess.opts.debugging_opts.nll {
+        None
+    } else {
         let mir = &mut mir;
 
         // Replace all regions with fresh inference variables.
-        nll::replace_regions_in_mir(infcx, src, mir)
+        Some(nll::replace_regions_in_mir(infcx, src, mir))
     };
     let mir = &mir;
 
@@ -119,7 +121,7 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
 
     let mdpe = MoveDataParamEnv { move_data: move_data, param_env: param_env };
     let dead_unwinds = IdxSetBuf::new_empty(mir.basic_blocks().len());
-    let flow_inits = FlowInProgress::new(do_dataflow(tcx, mir, id, &attributes, &dead_unwinds,
+    let mut flow_inits = FlowInProgress::new(do_dataflow(tcx, mir, id, &attributes, &dead_unwinds,
                                  MaybeInitializedLvals::new(tcx, mir, &mdpe),
                                  |bd, i| &bd.move_data().move_paths[i]));
     let flow_uninits = FlowInProgress::new(do_dataflow(tcx, mir, id, &attributes, &dead_unwinds,
@@ -133,13 +135,14 @@ fn do_mir_borrowck<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
         Some(nll::compute_regions(
             infcx,
             src,
-            &free_regions,
+            &free_regions.unwrap(),
             mir,
             param_env,
-            &flow_inits,
+            &mut flow_inits,
             &mdpe.move_data
         ))
     };
+    let flow_inits = flow_inits; // remove mut
 
     let mut mbcx = MirBorrowckCtxt {
         tcx: tcx,

src/librustc_mir/borrow_check/nll/constraint_generation.rs

@@ -13,7 +13,7 @@ use rustc::mir::{Location, Lvalue, Mir, Rvalue};
 use rustc::mir::transform::MirSource;
 use rustc::mir::visit::Visitor;
 use rustc::mir::Lvalue::Projection;
-use rustc::mir::{LvalueProjection, ProjectionElem};
+use rustc::mir::{LvalueProjection, ProjectionElem, Local};
 use rustc::infer::InferCtxt;
 use rustc::traits::{self, ObligationCause};
 use rustc::ty::{self, Ty};
@@ -35,7 +35,7 @@ pub(super) fn generate_constraints<'cx, 'gcx, 'tcx>(
     mir: &Mir<'tcx>,
     mir_source: MirSource,
     liveness: &LivenessResults,
-    flow_inits: &FlowInProgress<MaybeInitializedLvals<'cx, 'gcx, 'tcx>>,
+    flow_inits: &mut FlowInProgress<MaybeInitializedLvals<'cx, 'gcx, 'tcx>>,
     move_data: &MoveData<'tcx>,
 ) {
     ConstraintGeneration {
@@ -56,7 +56,7 @@ struct ConstraintGeneration<'cg, 'cx: 'cg, 'gcx: 'tcx, 'tcx: 'cx> {
     mir: &'cg Mir<'tcx>,
     liveness: &'cg LivenessResults,
     mir_source: MirSource,
-    flow_inits: &'cg FlowInProgress<MaybeInitializedLvals<'cx, 'gcx, 'tcx>>,
+    flow_inits: &'cg mut FlowInProgress<MaybeInitializedLvals<'cx, 'gcx, 'tcx>>,
     move_data: &'cg MoveData<'tcx>,
 }
 
@@ -84,19 +84,27 @@ impl<'cx, 'cg, 'gcx, 'tcx> ConstraintGeneration<'cx, 'cg, 'gcx, 'tcx> {
                     }
                 });
 
-            self.liveness.drop.simulate_block(
-                self.mir,
-                bb,
-                |location, live_locals| {
-                    for live_local in live_locals.iter() {
-                        let mpi = self.move_data.rev_lookup.find_local(live_local);
-                        if self.flow_inits.has_any_child_of(mpi).is_some() {
-                            let live_local_ty = self.mir.local_decls[live_local].ty;
-                            self.add_drop_live_constraint(live_local_ty, location);
-                        }
+            let mut all_live_locals: Vec<(Location, Vec<Local>)> = vec![];
+            self.liveness.drop.simulate_block(self.mir, bb, |location, live_locals| {
+                all_live_locals.push((location, live_locals.iter().collect()));
+            });
+
+            self.flow_inits.reset_to_entry_of(bb);
+            for index in 0 .. self.mir.basic_blocks()[bb].statements.len() {
+                let location = Location { block: bb, statement_index: index };
+                let (location2, live_locals) = all_live_locals.pop().unwrap();
+                assert_eq!(location, location2);
+
+                for live_local in live_locals {
+                    let mpi = self.move_data.rev_lookup.find_local(live_local);
+                    if self.flow_inits.has_any_child_of(mpi).is_some() {
+                        let live_local_ty = self.mir.local_decls[live_local].ty;
+                        self.add_drop_live_constraint(live_local_ty, location);
                     }
-                },
-            );
+                }
+
+                self.flow_inits.reconstruct_statement_effect(location);
+            }
         }
     }
 

src/librustc_mir/borrow_check/nll/mod.rs

@@ -37,8 +37,8 @@ mod renumber;
 /// scraping out the set of free regions (e.g., region parameters)
 /// declared on the function. That set will need to be given to
 /// `compute_regions`.
-pub(super) fn replace_regions_in_mir<'a, 'gcx, 'tcx>(
-    infcx: &InferCtxt<'a, 'gcx, 'tcx>,
+pub(super) fn replace_regions_in_mir<'cx, 'gcx, 'tcx>(
+    infcx: &InferCtxt<'cx, 'gcx, 'tcx>,
     source: MirSource,
     mir: &mut Mir<'tcx>
 ) -> FreeRegions<'tcx> {
@@ -54,13 +54,13 @@ pub(super) fn replace_regions_in_mir<'a, 'gcx, 'tcx>(
 /// Computes the (non-lexical) regions from the input MIR.
 ///
 /// This may result in errors being reported.
-pub(super) fn compute_regions<'a, 'gcx, 'tcx>(
-    infcx: &InferCtxt<'a, 'gcx, 'tcx>,
+pub(super) fn compute_regions<'cx, 'gcx, 'tcx>(
+    infcx: &InferCtxt<'cx, 'gcx, 'tcx>,
     source: MirSource,
     free_regions: &FreeRegions<'tcx>,
     mir: &Mir<'tcx>,
     param_env: ty::ParamEnv<'gcx>,
-    flow_inits: &FlowInProgress<MaybeInitializedLvals<'a, 'gcx, 'tcx>>,
+    flow_inits: &mut FlowInProgress<MaybeInitializedLvals<'cx, 'gcx, 'tcx>>,
     move_data: &MoveData<'tcx>,
 ) -> RegionInferenceContext<'tcx> {
     // Run the MIR type-checker.

src/test/ui/nll/maybe-initialized-drop.rs

@@ -7,8 +7,8 @@
 // <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.
-// revisions: mir
-//[mir]compile-flags: -Z emit-end-regions -Z borrowck-mir
+
+//compile-flags: -Z emit-end-regions -Z borrowck-mir -Z nll
 
 struct Wrap<'p> { p: &'p mut i32 }
 
@@ -43,6 +43,7 @@ fn baz_a() {
     let s = String::from("str");
     let foo = Foo { a: s, b: wrap };
     move_string(foo.a);
+    x += 1; //~ ERROR because of Foo.b's Wrap dtor
 }
 
 fn baz_a_b() {
@@ -52,6 +53,7 @@ fn baz_a_b() {
     let foo = Foo { a: s, b: wrap };
     move_string(foo.a);
     move_wrap(foo.b);
+    x += 1; // OK, drops are inert
 }
 
 fn baz_b() {
@@ -60,6 +62,8 @@ fn baz_b() {
     let s = String::from("str");
     let foo = Foo { a: s, b: wrap };
     move_wrap(foo.b);
+    x += 1; //~ ERROR because of Foo.a's implicit dtor
+    // FIXME ^ Should not error in the future with implicit dtors, only manually implemented ones
 }
 
 fn main() { }

src/test/ui/nll/maybe-initialized-drop.stderr

@@ -1,97 +1,46 @@
 error[E0506]: cannot assign to `x` because it is borrowed (Ast)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
+  --> $DIR/maybe-initialized-drop.rs:24:5
    |
 23 |     let wrap = Wrap { p: &mut x };
    |                               - borrow of `x` occurs here
 24 |     x += 1; //~ ERROR because of dtor
    |     ^^^^^^ assignment to borrowed `x` occurs here
 
 error[E0506]: cannot assign to `x` because it is borrowed (Ast)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
+  --> $DIR/maybe-initialized-drop.rs:31:5
    |
 29 |     let wrap = Wrap { p: &mut x };
    |                               - borrow of `x` occurs here
 30 |     std::mem::drop(wrap);
 31 |     x += 1; // OK, drop is inert
    |     ^^^^^^ assignment to borrowed `x` occurs here
 
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
-   |
-23 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-24 |     x += 1; //~ ERROR because of dtor
-   |     ^^^^^^ assignment to borrowed `x` occurs here
-
-error[E0503]: cannot use `x` because it was mutably borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:24:5
-   |
-23 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-24 |     x += 1; //~ ERROR because of dtor
-   |     ^^^^^^ use of borrowed `x`
-
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:25:2
-   |
-23 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-24 |     x += 1; //~ ERROR because of dtor
-25 | }
-   |  ^ assignment to borrowed `x` occurs here
-
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
-   |
-29 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-30 |     std::mem::drop(wrap);
-31 |     x += 1; // OK, drop is inert
-   |     ^^^^^^ assignment to borrowed `x` occurs here
-
-error[E0503]: cannot use `x` because it was mutably borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:31:5
-   |
-29 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-30 |     std::mem::drop(wrap);
-31 |     x += 1; // OK, drop is inert
-   |     ^^^^^^ use of borrowed `x`
-
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:32:2
-   |
-29 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
-...
-32 | }
-   |  ^ assignment to borrowed `x` occurs here
-
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:46:2
+error[E0506]: cannot assign to `x` because it is borrowed (Ast)
+  --> $DIR/maybe-initialized-drop.rs:46:5
    |
 42 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
+   |                               - borrow of `x` occurs here
 ...
-46 | }
-   |  ^ assignment to borrowed `x` occurs here
+46 |     x += 1; //~ ERROR because of Foo.b's Wrap dtor
+   |     ^^^^^^ assignment to borrowed `x` occurs here
 
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:55:2
+error[E0506]: cannot assign to `x` because it is borrowed (Ast)
+  --> $DIR/maybe-initialized-drop.rs:56:5
    |
-50 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
+51 |     let wrap = Wrap { p: &mut x };
+   |                               - borrow of `x` occurs here
 ...
-55 | }
-   |  ^ assignment to borrowed `x` occurs here
+56 |     x += 1; // OK, drops are inert
+   |     ^^^^^^ assignment to borrowed `x` occurs here
 
-error[E0506]: cannot assign to `x` because it is borrowed (Mir)
-  --> /home/paulf/rust/src/test/ui/nll/maybe-initialized-drop.rs:63:2
+error[E0506]: cannot assign to `x` because it is borrowed (Ast)
+  --> $DIR/maybe-initialized-drop.rs:65:5
    |
-59 |     let wrap = Wrap { p: &mut x };
-   |                          ------ borrow of `x` occurs here
+61 |     let wrap = Wrap { p: &mut x };
+   |                               - borrow of `x` occurs here
 ...
-63 | }
-   |  ^ assignment to borrowed `x` occurs here
+65 |     x += 1; //~ ERROR because of Foo.a's implicit dtor
+   |     ^^^^^^ assignment to borrowed `x` occurs here
+
+error: aborting due to 5 previous errors
 
-error: aborting due to 11 previous errors