Rollup merge of rust-lang#67325 - Centril:push-fake-read, r=matthewja…

…sper

cleanup with push_fake_read

...and make things a bit more readable.

r? @matthewjasper

src/librustc_mir/build/cfg.rs

@@ -59,6 +59,18 @@ impl<'tcx> CFG<'tcx> {
         ));
     }
 
+    pub fn push_fake_read(
+        &mut self,
+        block: BasicBlock,
+        source_info: SourceInfo,
+        cause: FakeReadCause,
+        place: Place<'tcx>,
+    ) {
+        let kind = StatementKind::FakeRead(cause, box place);
+        let stmt = Statement { source_info, kind };
+        self.push(block, stmt);
+    }
+
     pub fn terminate(&mut self,
                      block: BasicBlock,
                      source_info: SourceInfo,

src/librustc_mir/build/expr/as_place.rs

@@ -484,24 +484,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
     fn read_fake_borrows(
         &mut self,
-        block: BasicBlock,
+        bb: BasicBlock,
         fake_borrow_temps: &mut Vec<Local>,
         source_info: SourceInfo,
     ) {
         // All indexes have been evaluated now, read all of the
         // fake borrows so that they are live across those index
         // expressions.
         for temp in fake_borrow_temps {
-            self.cfg.push(
-                block,
-                Statement {
-                    source_info,
-                    kind: StatementKind::FakeRead(
-                        FakeReadCause::ForIndex,
-                        Box::new(Place::from(*temp)),
-                    )
-                }
-            );
+            self.cfg.push_fake_read(bb, source_info, FakeReadCause::ForIndex, Place::from(*temp));
         }
     }
 }

src/librustc_mir/build/matches/mod.rs

@@ -131,13 +131,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         // check safety.
 
         let source_info = self.source_info(scrutinee_span);
-        self.cfg.push(block, Statement {
-            source_info,
-            kind: StatementKind::FakeRead(
-                FakeReadCause::ForMatchedPlace,
-                box(scrutinee_place.clone()),
-            ),
-        });
+        let cause_matched_place = FakeReadCause::ForMatchedPlace;
+        self.cfg.push_fake_read(block, source_info, cause_matched_place, scrutinee_place.clone());
 
         // Step 2. Create the otherwise and prebinding blocks.
 
@@ -313,16 +308,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     self.storage_live_binding(block, var, irrefutable_pat.span, OutsideGuard);
                 unpack!(block = self.into(&place, block, initializer));
 
-
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
                 let source_info = self.source_info(irrefutable_pat.span);
-                self.cfg.push(
-                    block,
-                    Statement {
-                        source_info,
-                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, box(place)),
-                    },
-                );
+                self.cfg.push_fake_read(block, source_info, FakeReadCause::ForLet, place);
 
                 self.schedule_drop_for_binding(var, irrefutable_pat.span, OutsideGuard);
                 block.unit()
@@ -358,13 +346,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 // Inject a fake read, see comments on `FakeReadCause::ForLet`.
                 let pattern_source_info = self.source_info(irrefutable_pat.span);
-                self.cfg.push(
-                    block,
-                    Statement {
-                        source_info: pattern_source_info,
-                        kind: StatementKind::FakeRead(FakeReadCause::ForLet, box(place.clone())),
-                    },
-                );
+                let cause_let = FakeReadCause::ForLet;
+                self.cfg.push_fake_read(block, pattern_source_info, cause_let, place.clone());
 
                 let ty_source_info = self.source_info(user_ty_span);
                 let user_ty = pat_ascription_ty.user_ty(
@@ -1515,13 +1498,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             );
 
             for &(_, temp) in fake_borrows {
-                self.cfg.push(post_guard_block, Statement {
-                    source_info: guard_end,
-                    kind: StatementKind::FakeRead(
-                        FakeReadCause::ForMatchGuard,
-                        box(Place::from(temp)),
-                    ),
-                });
+                let cause = FakeReadCause::ForMatchGuard;
+                self.cfg.push_fake_read(post_guard_block, guard_end, cause, Place::from(temp));
             }
 
             self.exit_scope(
@@ -1564,14 +1542,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             // place they refer to can't be modified by the guard.
             for binding in by_value_bindings.clone() {
                 let local_id = self.var_local_id(binding.var_id, RefWithinGuard);
-                let place = Place::from(local_id);
-                self.cfg.push(
-                    post_guard_block,
-                    Statement {
-                        source_info: guard_end,
-                        kind: StatementKind::FakeRead(FakeReadCause::ForGuardBinding, box(place)),
-                    },
-                );
+                let cause = FakeReadCause::ForGuardBinding;
+                self.cfg.push_fake_read(post_guard_block, guard_end, cause, Place::from(local_id));
             }
             self.bind_matched_candidate_for_arm_body(
                 post_guard_block,