Auto merge of rust-lang#70449 - ecstatic-morse:visit-body, r=oli-obk

Make `Visitor::visit_body` take a plain `&Body`

`ReadOnlyBodyAndCache` has replaced `&Body` in many parts of the code base that don't care about basic block predecessors. This includes the MIR `Visitor` trait, which I suspect resulted in many unnecessary changes in rust-lang#64736. This reverts part of that PR to reduce the number of places where we need to pass a `ReadOnlyBodyAndCache`.

In the long term, we should either give `ReadOnlyBodyAndCache` more ergonomic name and replace all uses of `&mir::Body` with it at the cost of carrying an extra pointer everywhere, or use it only in places that actually need access to the predecessor cache. Perhaps there is an even nicer alternative.

r? @Nashenas88

Author: bors

src/librustc/mir/visit.rs

@@ -65,12 +65,12 @@ use rustc_span::Span;
 // variant argument) that does not require visiting, as in
 // `is_cleanup` above.
 
-macro_rules! body_cache_type {
-    (mut $a:lifetime, $tcx:lifetime) => {
+macro_rules! body_type {
+    (mut $tcx:lifetime) => {
         &mut BodyAndCache<$tcx>
     };
-    ($a:lifetime, $tcx:lifetime) => {
-        ReadOnlyBodyAndCache<$a, $tcx>
+    ($tcx:lifetime) => {
+        &Body<$tcx>
     };
 }
 
@@ -82,7 +82,7 @@ macro_rules! make_mir_visitor {
 
             fn visit_body(
                 &mut self,
-                body: body_cache_type!($($mutability)? '_, 'tcx)
+                body: body_type!($($mutability)? 'tcx)
             ) {
                 self.super_body(body);
             }
@@ -254,7 +254,7 @@ macro_rules! make_mir_visitor {
 
             fn super_body(
                 &mut self,
-                $($mutability)? body: body_cache_type!($($mutability)? '_, 'tcx)
+                $($mutability)? body: body_type!($($mutability)? 'tcx)
             ) {
                 let span = body.span;
                 if let Some(yield_ty) = &$($mutability)? body.yield_ty {
@@ -819,7 +819,7 @@ macro_rules! make_mir_visitor {
 
             fn visit_location(
                 &mut self,
-                body: body_cache_type!($($mutability)? '_, 'tcx),
+                body: body_type!($($mutability)? 'tcx),
                 location: Location
             ) {
                 let basic_block = & $($mutability)? body[location.block];

src/librustc_codegen_ssa/mir/analyze.rs

@@ -20,7 +20,7 @@ pub fn non_ssa_locals<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     let mir = fx.mir;
     let mut analyzer = LocalAnalyzer::new(fx);
 
-    analyzer.visit_body(mir);
+    analyzer.visit_body(&mir);
 
     for (local, decl) in mir.local_decls.iter_enumerated() {
         let ty = fx.monomorphize(&decl.ty);

src/librustc_mir/borrow_check/borrow_set.rs

@@ -107,7 +107,7 @@ impl LocalsStateAtExit {
             LocalsStateAtExit::AllAreInvalidated
         } else {
             let mut has_storage_dead = HasStorageDead(BitSet::new_empty(body.local_decls.len()));
-            has_storage_dead.visit_body(body);
+            has_storage_dead.visit_body(&body);
             let mut has_storage_dead_or_moved = has_storage_dead.0;
             for move_out in &move_data.moves {
                 if let Some(index) = move_data.base_local(move_out.path) {

src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs

@@ -1559,7 +1559,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
         }
         let mut visitor = FakeReadCauseFinder { place, cause: None };
-        visitor.visit_body(self.body);
+        visitor.visit_body(&self.body);
         match visitor.cause {
             Some(FakeReadCause::ForMatchGuard) => Some("match guard"),
             Some(FakeReadCause::ForIndex) => Some("indexing expression"),

src/librustc_mir/borrow_check/invalidation.rs

@@ -37,7 +37,7 @@ pub(super) fn generate_invalidates<'tcx>(
             body: &body,
             dominators,
         };
-        ig.visit_body(body);
+        ig.visit_body(&body);
     }
 }
 

src/librustc_mir/borrow_check/mod.rs

@@ -299,8 +299,8 @@ fn do_mir_borrowck<'a, 'tcx>(
     }
 
     dataflow::visit_results(
-        &*body,
-        traversal::reverse_postorder(&*body).map(|(bb, _)| bb),
+        &body,
+        traversal::reverse_postorder(&body).map(|(bb, _)| bb),
         &results,
         &mut mbcx,
     );

src/librustc_mir/borrow_check/type_check/liveness/local_use_map.rs

@@ -81,7 +81,7 @@ impl LocalUseMap {
         live_locals.iter().for_each(|&local| locals_with_use_data[local] = true);
 
         LocalUseMapBuild { local_use_map: &mut local_use_map, elements, locals_with_use_data }
-            .visit_body(body);
+            .visit_body(&body);
 
         local_use_map
     }

src/librustc_mir/borrow_check/type_check/liveness/polonius.rs

@@ -101,7 +101,7 @@ pub(super) fn populate_access_facts(
             location_table,
             move_data,
         };
-        extractor.visit_body(body);
+        extractor.visit_body(&body);
 
         facts.var_dropped_at.extend(
             dropped_at.iter().map(|&(local, location)| (local, location_table.mid_index(location))),

src/librustc_mir/borrow_check/type_check/mod.rs

@@ -210,7 +210,7 @@ fn type_check_internal<'a, 'tcx, R>(
     );
     let errors_reported = {
         let mut verifier = TypeVerifier::new(&mut checker, *body, promoted);
-        verifier.visit_body(body);
+        verifier.visit_body(&body);
         verifier.errors_reported
     };
 
@@ -435,7 +435,7 @@ impl<'a, 'b, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'tcx> {
         }
     }
 
-    fn visit_body(&mut self, body: ReadOnlyBodyAndCache<'_, 'tcx>) {
+    fn visit_body(&mut self, body: &Body<'tcx>) {
         self.sanitize_type(&"return type", body.return_ty());
         for local_decl in &body.local_decls {
             self.sanitize_type(local_decl, local_decl.ty);
@@ -563,7 +563,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
 
         swap_constraints(self);
 
-        self.visit_body(promoted_body);
+        self.visit_body(&promoted_body);
 
         if !self.errors_reported {
             // if verifier failed, don't do further checks to avoid ICEs

src/librustc_mir/borrow_check/used_muts.rs

@@ -32,7 +32,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 never_initialized_mut_locals: &mut never_initialized_mut_locals,
                 mbcx: self,
             };
-            visitor.visit_body(visitor.mbcx.body);
+            visitor.visit_body(&visitor.mbcx.body);
         }
 
         // Take the union of the existed `used_mut` set with those variables we've found were