Rollup merge of rust-lang#101996 - b-naber:binder-print, r=lcnr

Don't duplicate region names for late-bound regions in print of Binder Fixes rust-lang#101280
matthiaskrgr · Sep 22, 2022 · 4e6d2d9 · 4e6d2d9
2 parents 6763980 + 953d88b
commit 4e6d2d9
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Showing 108 changed files with 313 additions and 234 deletions.
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1572,7 +1572,9 @@ pub struct FmtPrinterData<'a, 'tcx> {
     in_value: bool,
     pub print_alloc_ids: bool,
 
+    // set of all named (non-anonymous) region names
     used_region_names: FxHashSet<Symbol>,
+
     region_index: usize,
     binder_depth: usize,
     printed_type_count: usize,
@@ -2139,23 +2141,31 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
     where
         T: Print<'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>,
     {
-        fn name_by_region_index(index: usize) -> Symbol {
-            match index {
-                0 => Symbol::intern("'r"),
-                1 => Symbol::intern("'s"),
-                i => Symbol::intern(&format!("'t{}", i - 2)),
+        fn name_by_region_index(
+            index: usize,
+            available_names: &mut Vec<Symbol>,
+            num_available: usize,
+        ) -> Symbol {
+            if let Some(name) = available_names.pop() {
+                name
+            } else {
+                Symbol::intern(&format!("'z{}", index - num_available))
             }
         }
 
+        debug!("name_all_regions");
+
         // Replace any anonymous late-bound regions with named
         // variants, using new unique identifiers, so that we can
         // clearly differentiate between named and unnamed regions in
         // the output. We'll probably want to tweak this over time to
         // decide just how much information to give.
         if self.binder_depth == 0 {
-            self.prepare_late_bound_region_info(value);
+            self.prepare_region_info(value);
         }
 
+        debug!("self.used_region_names: {:?}", &self.used_region_names);
+
         let mut empty = true;
         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
             let w = if empty {
@@ -2172,13 +2182,24 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 
         define_scoped_cx!(self);
 
+        let possible_names =
+            ('a'..='z').rev().map(|s| Symbol::intern(&format!("'{s}"))).collect::<Vec<_>>();
+
+        let mut available_names = possible_names
+            .into_iter()
+            .filter(|name| !self.used_region_names.contains(&name))
+            .collect::<Vec<_>>();
+        debug!(?available_names);
+        let num_available = available_names.len();
+
         let mut region_index = self.region_index;
-        let mut next_name = |this: &Self| loop {
-            let name = name_by_region_index(region_index);
+        let mut next_name = |this: &Self| {
+            let name = name_by_region_index(region_index, &mut available_names, num_available);
+            debug!(?name);
             region_index += 1;
-            if !this.used_region_names.contains(&name) {
-                break name;
-            }
+            assert!(!this.used_region_names.contains(&name));
+
+            name
         };
 
         // If we want to print verbosely, then print *all* binders, even if they
@@ -2199,6 +2220,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
                         ty::BrAnon(_) | ty::BrEnv => {
                             start_or_continue(&mut self, "for<", ", ");
                             let name = next_name(&self);
+                            debug!(?name);
                             do_continue(&mut self, name);
                             ty::BrNamed(CRATE_DEF_ID.to_def_id(), name)
                         }
@@ -2292,29 +2314,37 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
         Ok(inner)
     }
 
-    fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
+    fn prepare_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
     where
         T: TypeVisitable<'tcx>,
     {
-        struct LateBoundRegionNameCollector<'a, 'tcx> {
-            used_region_names: &'a mut FxHashSet<Symbol>,
+        struct RegionNameCollector<'tcx> {
+            used_region_names: FxHashSet<Symbol>,
             type_collector: SsoHashSet<Ty<'tcx>>,
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_, 'tcx> {
+        impl<'tcx> RegionNameCollector<'tcx> {
+            fn new() -> Self {
+                RegionNameCollector {
+                    used_region_names: Default::default(),
+                    type_collector: SsoHashSet::new(),
+                }
+            }
+        }
+
+        impl<'tcx> ty::visit::TypeVisitor<'tcx> for RegionNameCollector<'tcx> {
             type BreakTy = ();
 
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
                 trace!("address: {:p}", r.0.0);
-                if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r {
-                    self.used_region_names.insert(name);
-                } else if let ty::RePlaceholder(ty::PlaceholderRegion {
-                    name: ty::BrNamed(_, name),
-                    ..
-                }) = *r
-                {
+
+                // Collect all named lifetimes. These allow us to prevent duplication
+                // of already existing lifetime names when introducing names for
+                // anonymous late-bound regions.
+                if let Some(name) = r.get_name() {
                     self.used_region_names.insert(name);
                 }
+
                 r.super_visit_with(self)
             }
 
@@ -2330,12 +2360,9 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
             }
         }
 
-        self.used_region_names.clear();
-        let mut collector = LateBoundRegionNameCollector {
-            used_region_names: &mut self.used_region_names,
-            type_collector: SsoHashSet::new(),
-        };
+        let mut collector = RegionNameCollector::new();
         value.visit_with(&mut collector);
+        self.used_region_names = collector.used_region_names;
         self.region_index = 0;
     }
 }

diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
@@ -85,6 +85,17 @@ impl BoundRegionKind {
             _ => false,
         }
     }
+
+    pub fn get_name(&self) -> Option<Symbol> {
+        if self.is_named() {
+            match *self {
+                BoundRegionKind::BrNamed(_, name) => return Some(name),
+                _ => unreachable!(),
+            }
+        }
+
+        None
+    }
 }
 
 pub trait Article {
@@ -1441,6 +1452,23 @@ impl<'tcx> Region<'tcx> {
         *self.0.0
     }
 
+    pub fn get_name(self) -> Option<Symbol> {
+        if self.has_name() {
+            let name = match *self {
+                ty::ReEarlyBound(ebr) => Some(ebr.name),
+                ty::ReLateBound(_, br) => br.kind.get_name(),
+                ty::ReFree(fr) => fr.bound_region.get_name(),
+                ty::ReStatic => Some(kw::StaticLifetime),
+                ty::RePlaceholder(placeholder) => placeholder.name.get_name(),
+                _ => None,
+            };
+
+            return name;
+        }
+
+        None
+    }
+
     /// Is this region named by the user?
     pub fn has_name(self) -> bool {
         match *self {

diff --git a/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff b/src/test/mir-opt/combine_clone_of_primitives.{impl#0}-clone.InstCombine.diff
@@ -24,7 +24,7 @@
           _2 = <T as Clone>::clone(move _3) -> bb1; // scope 0 at $DIR/combine_clone_of_primitives.rs:8:5: 8:9
                                            // mir::Constant
                                            // + span: $DIR/combine_clone_of_primitives.rs:8:5: 8:9
-                                           // + literal: Const { ty: for<'r> fn(&'r T) -> T {<T as Clone>::clone}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a T) -> T {<T as Clone>::clone}, val: Value(<ZST>) }
       }
 
       bb1: {
@@ -37,7 +37,7 @@
 -         _5 = <u64 as Clone>::clone(move _6) -> [return: bb2, unwind: bb4]; // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 -                                          // mir::Constant
 -                                          // + span: $DIR/combine_clone_of_primitives.rs:9:5: 9:11
--                                          // + literal: Const { ty: for<'r> fn(&'r u64) -> u64 {<u64 as Clone>::clone}, val: Value(<ZST>) }
+-                                          // + literal: Const { ty: for<'a> fn(&'a u64) -> u64 {<u64 as Clone>::clone}, val: Value(<ZST>) }
 +         _6 = _7;                         // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 +         _5 = (*_6);                      // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
 +         goto -> bb2;                     // scope 0 at $DIR/combine_clone_of_primitives.rs:9:5: 9:11
@@ -53,7 +53,7 @@
 -         _8 = <[f32; 3] as Clone>::clone(move _9) -> [return: bb3, unwind: bb4]; // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 -                                          // mir::Constant
 -                                          // + span: $DIR/combine_clone_of_primitives.rs:10:5: 10:16
--                                          // + literal: Const { ty: for<'r> fn(&'r [f32; 3]) -> [f32; 3] {<[f32; 3] as Clone>::clone}, val: Value(<ZST>) }
+-                                          // + literal: Const { ty: for<'a> fn(&'a [f32; 3]) -> [f32; 3] {<[f32; 3] as Clone>::clone}, val: Value(<ZST>) }
 +         _9 = _10;                        // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 +         _8 = (*_9);                      // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16
 +         goto -> bb3;                     // scope 0 at $DIR/combine_clone_of_primitives.rs:10:5: 10:16

diff --git a/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
@@ -33,7 +33,7 @@
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:+0:31: +0:44
                                            // mir::Constant
                                            // + span: $DIR/const-promotion-extern-static.rs:9:36: 9:42
-                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
       }
 
       bb1: {

diff --git a/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
@@ -35,7 +35,7 @@
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:+0:31: +0:55
                                            // mir::Constant
                                            // + span: $DIR/const-promotion-extern-static.rs:13:47: 13:53
-                                           // + literal: Const { ty: for<'r> fn(&'r [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a [&i32]) -> *const &i32 {core::slice::<impl [&i32]>::as_ptr}, val: Value(<ZST>) }
       }
 
       bb1: {

diff --git a/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff b/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
@@ -20,7 +20,7 @@
           _2 = core::str::<impl str>::as_bytes(move _3) -> bb1; // scope 0 at $DIR/deduplicate_blocks.rs:+1:11: +1:23
                                            // mir::Constant
                                            // + span: $DIR/deduplicate_blocks.rs:5:13: 5:21
-                                           // + literal: Const { ty: for<'r> fn(&'r str) -> &'r [u8] {core::str::<impl str>::as_bytes}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a str) -> &'a [u8] {core::str::<impl str>::as_bytes}, val: Value(<ZST>) }
       }
 
       bb1: {

diff --git a/src/test/mir-opt/derefer_complex_case.main.Derefer.diff b/src/test/mir-opt/derefer_complex_case.main.Derefer.diff
@@ -56,7 +56,7 @@
           _7 = <std::slice::Iter<i32> as Iterator>::next(move _8) -> bb3; // scope 1 at $DIR/derefer_complex_case.rs:+1:17: +1:26
                                            // mir::Constant
                                            // + span: $DIR/derefer_complex_case.rs:6:17: 6:26
-                                           // + literal: Const { ty: for<'r> fn(&'r mut std::slice::Iter<i32>) -> Option<<std::slice::Iter<i32> as Iterator>::Item> {<std::slice::Iter<i32> as Iterator>::next}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a mut std::slice::Iter<i32>) -> Option<<std::slice::Iter<i32> as Iterator>::Item> {<std::slice::Iter<i32> as Iterator>::next}, val: Value(<ZST>) }
       }
 
       bb3: {

diff --git a/src/test/mir-opt/dest-prop/simple.nrvo.DestinationPropagation.diff b/src/test/mir-opt/dest-prop/simple.nrvo.DestinationPropagation.diff
@@ -1,12 +1,12 @@
 - // MIR for `nrvo` before DestinationPropagation
 + // MIR for `nrvo` after DestinationPropagation
 
-  fn nrvo(_1: for<'r> fn(&'r mut [u8; 1024])) -> [u8; 1024] {
+  fn nrvo(_1: for<'a> fn(&'a mut [u8; 1024])) -> [u8; 1024] {
       debug init => _1;                    // in scope 0 at $DIR/simple.rs:+0:9: +0:13
       let mut _0: [u8; 1024];              // return place in scope 0 at $DIR/simple.rs:+0:39: +0:49
       let mut _2: [u8; 1024];              // in scope 0 at $DIR/simple.rs:+1:9: +1:16
       let _3: ();                          // in scope 0 at $DIR/simple.rs:+2:5: +2:19
-      let mut _4: for<'r> fn(&'r mut [u8; 1024]); // in scope 0 at $DIR/simple.rs:+2:5: +2:9
+      let mut _4: for<'a> fn(&'a mut [u8; 1024]); // in scope 0 at $DIR/simple.rs:+2:5: +2:9
       let mut _5: &mut [u8; 1024];         // in scope 0 at $DIR/simple.rs:+2:10: +2:18
       let mut _6: &mut [u8; 1024];         // in scope 0 at $DIR/simple.rs:+2:10: +2:18
       scope 1 {

diff --git a/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff b/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
@@ -41,7 +41,7 @@
           _4 = Formatter::sign_plus(move _5) -> bb1; // scope 0 at $DIR/funky_arms.rs:+4:22: +4:37
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:15:26: 15:35
-                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> bool {Formatter::sign_plus}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a Formatter) -> bool {Formatter::sign_plus}, val: Value(<ZST>) }
       }
 
       bb1: {
@@ -69,7 +69,7 @@
           _7 = Formatter::precision(move _8) -> bb5; // scope 3 at $DIR/funky_arms.rs:+13:30: +13:45
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:24:34: 24:43
-                                           // + literal: Const { ty: for<'r> fn(&'r Formatter) -> Option<usize> {Formatter::precision}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a Formatter) -> Option<usize> {Formatter::precision}, val: Value(<ZST>) }
       }
 
       bb5: {
@@ -100,7 +100,7 @@
           _0 = float_to_exponential_common_exact::<T>(move _11, move _12, move _13, move _14, move _17) -> bb7; // scope 3 at $DIR/funky_arms.rs:+15:9: +15:87
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:26:9: 26:42
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, u32, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_exact::<T>}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a, 'b, 'c> fn(&'a mut Formatter<'b>, &'c T, Sign, u32, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_exact::<T>}, val: Value(<ZST>) }
       }
 
       bb7: {
@@ -125,7 +125,7 @@
           _0 = float_to_exponential_common_shortest::<T>(move _18, move _19, move _20, move _21) -> bb9; // scope 2 at $DIR/funky_arms.rs:+17:9: +17:68
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:28:9: 28:45
-                                           // + literal: Const { ty: for<'r, 's, 't0> fn(&'r mut Formatter<'s>, &'t0 T, Sign, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_shortest::<T>}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a, 'b, 'c> fn(&'a mut Formatter<'b>, &'c T, Sign, bool) -> Result<(), std::fmt::Error> {float_to_exponential_common_shortest::<T>}, val: Value(<ZST>) }
       }
 
       bb9: {

diff --git a/src/test/mir-opt/inline/cycle.f.Inline.diff b/src/test/mir-opt/inline/cycle.f.Inline.diff
@@ -17,7 +17,7 @@
           _2 = <impl Fn() as Fn<()>>::call(move _3, move _4) -> [return: bb1, unwind: bb3]; // scope 0 at $DIR/cycle.rs:+1:5: +1:8
                                            // mir::Constant
                                            // + span: $DIR/cycle.rs:6:5: 6:6
-                                           // + literal: Const { ty: for<'r> extern "rust-call" fn(&'r impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> extern "rust-call" fn(&'a impl Fn(), ()) -> <impl Fn() as FnOnce<()>>::Output {<impl Fn() as Fn<()>>::call}, val: Value(<ZST>) }
       }
 
       bb1: {

diff --git a/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff b/src/test/mir-opt/inline/dyn_trait.get_query.Inline.diff
@@ -28,7 +28,7 @@
                                            // mir::Constant
                                            // + span: $DIR/dyn-trait.rs:33:13: 33:21
                                            // + user_ty: UserType(0)
-                                           // + literal: Const { ty: for<'r> fn(&'r T) -> &'r <Q as Query>::C {<Q as Query>::cache::<T>}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a T) -> &'a <Q as Query>::C {<Q as Query>::cache::<T>}, val: Value(<ZST>) }
       }
 
       bb1: {
@@ -46,9 +46,9 @@
 +         _0 = <dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache(move _7) -> bb2; // scope 3 at $DIR/dyn-trait.rs:21:5: 21:22
                                            // mir::Constant
 -                                          // + span: $DIR/dyn-trait.rs:34:5: 34:22
--                                          // + literal: Const { ty: for<'r> fn(&'r <Q as Query>::C) {try_execute_query::<<Q as Query>::C>}, val: Value(<ZST>) }
+-                                          // + literal: Const { ty: for<'a> fn(&'a <Q as Query>::C) {try_execute_query::<<Q as Query>::C>}, val: Value(<ZST>) }
 +                                          // + span: $DIR/dyn-trait.rs:21:7: 21:20
-+                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <Q as Query>::V>) {<dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
++                                          // + literal: Const { ty: for<'a> fn(&'a dyn Cache<V = <Q as Query>::V>) {<dyn Cache<V = <Q as Query>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
 
       bb2: {

diff --git a/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff b/src/test/mir-opt/inline/dyn_trait.mk_cycle.Inline.diff
@@ -12,7 +12,7 @@
           _0 = <dyn Cache<V = V> as Cache>::store_nocache(move _2) -> bb1; // scope 0 at $DIR/dyn-trait.rs:+1:5: +1:22
                                            // mir::Constant
                                            // + span: $DIR/dyn-trait.rs:21:7: 21:20
-                                           // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = V>) {<dyn Cache<V = V> as Cache>::store_nocache}, val: Value(<ZST>) }
+                                           // + literal: Const { ty: for<'a> fn(&'a dyn Cache<V = V>) {<dyn Cache<V = V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
 
       bb1: {

diff --git a/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff b/src/test/mir-opt/inline/dyn_trait.try_execute_query.Inline.diff
@@ -23,9 +23,9 @@
 +         _0 = <dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache(move _4) -> bb1; // scope 1 at $DIR/dyn-trait.rs:21:5: 21:22
                                            // mir::Constant
 -                                          // + span: $DIR/dyn-trait.rs:27:5: 27:13
--                                          // + literal: Const { ty: for<'r> fn(&'r (dyn Cache<V = <C as Cache>::V> + 'r)) {mk_cycle::<<C as Cache>::V>}, val: Value(<ZST>) }
+-                                          // + literal: Const { ty: for<'a> fn(&'a (dyn Cache<V = <C as Cache>::V> + 'a)) {mk_cycle::<<C as Cache>::V>}, val: Value(<ZST>) }
 +                                          // + span: $DIR/dyn-trait.rs:21:7: 21:20
-+                                          // + literal: Const { ty: for<'r> fn(&'r dyn Cache<V = <C as Cache>::V>) {<dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
++                                          // + literal: Const { ty: for<'a> fn(&'a dyn Cache<V = <C as Cache>::V>) {<dyn Cache<V = <C as Cache>::V> as Cache>::store_nocache}, val: Value(<ZST>) }
       }
 
       bb1: {