Rollup merge of #137863 - compiler-errors:unsafe-binder-render, r=oli-obk

Fix pretty printing of unsafe binders
We used to render `unsafe<> i32` as `i32`, and `unsafe<'a> &'a i32` as `for<'a> &'a i32`.
r? oli-obk
Review with whitespace b/c adding a new argument changes some the wrapping of some function calls.

Author: matthiaskrgr

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -133,6 +133,20 @@ pub macro with_no_queries($e:expr) {{
 ))
 }}
 
+#[derive(Copy,Clone,Debug,PartialEq,Eq)]
+pubenumWrapBinderMode{
+ForAll,
+Unsafe,
+}
+implWrapBinderMode{
+pubfnstart_str(self) -> &'staticstr{
+matchself{
+WrapBinderMode::ForAll => "for<",
+WrapBinderMode::Unsafe => "unsafe<",
+}
+}
+}
+
 /// The "region highlights" are used to control region printing during
 /// specific error messages. When a "region highlight" is enabled, it
 /// gives an alternate way to print specific regions. For now, we
@@ -219,7 +233,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 self.print_def_path(def_id, args)
 }
 
-fnin_binder<T>(&mutself,value:&ty::Binder<'tcx,T>) -> Result<(),PrintError>
+fnprint_in_binder<T>(&mutself,value:&ty::Binder<'tcx,T>) -> Result<(),PrintError>
 where
 T:Print<'tcx,Self> + TypeFoldable<TyCtxt<'tcx>>,
 {
@@ -229,6 +243,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 fnwrap_binder<T,F:FnOnce(&T,&mutSelf) -> Result<(), fmt::Error>>(
 &mutself,
 value:&ty::Binder<'tcx,T>,
+_mode:WrapBinderMode,
 f:F,
 ) -> Result<(),PrintError>
 where
@@ -703,8 +718,9 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 }
  ty::FnPtr(ref sig_tys, hdr) => p!(print(sig_tys.with(hdr))),
  ty::UnsafeBinder(ref bound_ty) => {
-// FIXME(unsafe_binders): Make this print `unsafe<>` rather than `for<>`.
-self.wrap_binder(bound_ty, |ty, cx| cx.pretty_print_type(*ty))?;
+self.wrap_binder(bound_ty,WrapBinderMode::Unsafe, |ty, cx| {
+ cx.pretty_print_type(*ty)
+})?;
 }
  ty::Infer(infer_ty) => {
 ifself.should_print_verbose(){
@@ -1067,29 +1083,33 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 };
 
 ifletSome(return_ty) = entry.return_ty{
-self.wrap_binder(&bound_args_and_self_ty, |(args, _), cx| {
-define_scoped_cx!(cx);
-p!(write("{}", tcx.item_name(trait_def_id)));
-p!("(");
-
-for(idx, ty)in args.iter().enumerate(){
-if idx > 0{
-p!(", ");
+self.wrap_binder(
+&bound_args_and_self_ty,
+WrapBinderMode::ForAll,
+ |(args, _), cx| {
+define_scoped_cx!(cx);
+p!(write("{}", tcx.item_name(trait_def_id)));
+p!("(");
+
+for(idx, ty)in args.iter().enumerate(){
+if idx > 0{
+p!(", ");
+}
+p!(print(ty));
 }
-p!(print(ty));
-}
 
-p!(")");
-ifletSome(ty) = return_ty.skip_binder().as_type(){
-if !ty.is_unit(){
-p!(" -> ", print(return_ty));
+p!(")");
+ifletSome(ty) = return_ty.skip_binder().as_type(){
+if !ty.is_unit(){
+p!(" -> ", print(return_ty));
+}
 }
-}
-p!(write("{}",if paren_needed {")"} else {""}));
+p!(write("{}",if paren_needed {")"} else {""}));
 
- first = false;
-Ok(())
-})?;
+ first = false;
+Ok(())
+},
+)?;
 }else{
 // Otherwise, render this like a regular trait.
  traits.insert(
@@ -1110,7 +1130,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 for(trait_pred, assoc_items)in traits {
 write!(self,"{}",if first {""} else {" + "})?;
 
-self.wrap_binder(&trait_pred, |trait_pred, cx| {
+self.wrap_binder(&trait_pred,WrapBinderMode::ForAll,|trait_pred, cx| {
 define_scoped_cx!(cx);
 
 if trait_pred.polarity == ty::PredicatePolarity::Negative{
@@ -1302,7 +1322,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 letmut first = true;
 
 ifletSome(bound_principal) = predicates.principal(){
-self.wrap_binder(&bound_principal, |principal, cx| {
+self.wrap_binder(&bound_principal,WrapBinderMode::ForAll,|principal, cx| {
 define_scoped_cx!(cx);
 p!(print_def_path(principal.def_id,&[]));
 
@@ -1927,7 +1947,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
 let kind = closure.kind_ty().to_opt_closure_kind().unwrap_or(ty::ClosureKind::Fn);
 
 write!(self,"impl ")?;
-self.wrap_binder(&sig, |sig, cx| {
+self.wrap_binder(&sig,WrapBinderMode::ForAll,|sig, cx| {
 define_scoped_cx!(cx);
 
 p!(write("{kind}("));
@@ -2367,22 +2387,23 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
 Ok(())
 }
 
-fnin_binder<T>(&mutself,value:&ty::Binder<'tcx,T>) -> Result<(),PrintError>
+fnprint_in_binder<T>(&mutself,value:&ty::Binder<'tcx,T>) -> Result<(),PrintError>
 where
 T:Print<'tcx,Self> + TypeFoldable<TyCtxt<'tcx>>,
 {
-self.pretty_in_binder(value)
+self.pretty_print_in_binder(value)
 }
 
 fnwrap_binder<T,C:FnOnce(&T,&mutSelf) -> Result<(),PrintError>>(
 &mutself,
 value:&ty::Binder<'tcx,T>,
+mode:WrapBinderMode,
 f:C,
 ) -> Result<(),PrintError>
 where
 T:TypeFoldable<TyCtxt<'tcx>>,
 {
-self.pretty_wrap_binder(value, f)
+self.pretty_wrap_binder(value,mode,f)
 }
 
 fntyped_value(
@@ -2632,6 +2653,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 pubfnname_all_regions<T>(
 &mutself,
 value:&ty::Binder<'tcx,T>,
+mode:WrapBinderMode,
 ) -> Result<(T,UnordMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>
 where
 T:TypeFoldable<TyCtxt<'tcx>>,
@@ -2705,9 +2727,13 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 // anyways.
 let(new_value, map) = ifself.should_print_verbose(){
 for var in value.bound_vars().iter(){
-start_or_continue(self,"for<",", ");
+start_or_continue(self,mode.start_str(),", ");
 write!(self,"{var:?}")?;
 }
+// Unconditionally render `unsafe<>`.
+if value.bound_vars().is_empty() && mode == WrapBinderMode::Unsafe{
+start_or_continue(self, mode.start_str(),"");
+}
 start_or_continue(self,"","> ");
 (value.clone().skip_binder(),UnordMap::default())
 }else{
@@ -2772,8 +2798,9 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 }
 };
 
-if !trim_path {
-start_or_continue(self,"for<",", ");
+// Unconditionally render `unsafe<>`.
+if !trim_path || mode == WrapBinderMode::Unsafe{
+start_or_continue(self, mode.start_str(),", ");
 do_continue(self, name);
 }
  ty::Region::new_bound(tcx, ty::INNERMOST, ty::BoundRegion{var: br.var, kind })
@@ -2786,9 +2813,12 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 };
 let new_value = value.clone().skip_binder().fold_with(&mut folder);
 let region_map = folder.region_map;
-if !trim_path {
-start_or_continue(self,"","> ");
+
+if mode == WrapBinderMode::Unsafe && region_map.is_empty(){
+start_or_continue(self, mode.start_str(),"");
 }
+start_or_continue(self,"","> ");
+
 (new_value, region_map)
 };
 
@@ -2797,12 +2827,15 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 Ok((new_value, map))
 }
 
-pubfnpretty_in_binder<T>(&mutself,value:&ty::Binder<'tcx,T>) -> Result<(), fmt::Error>
+pubfnpretty_print_in_binder<T>(
+&mutself,
+value:&ty::Binder<'tcx,T>,
+) -> Result<(), fmt::Error>
 where
 T:Print<'tcx,Self> + TypeFoldable<TyCtxt<'tcx>>,
 {
 let old_region_index = self.region_index;
-let(new_value, _) = self.name_all_regions(value)?;
+let(new_value, _) = self.name_all_regions(value,WrapBinderMode::ForAll)?;
  new_value.print(self)?;
 self.region_index = old_region_index;
 self.binder_depth -= 1;
@@ -2812,13 +2845,14 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
 pubfnpretty_wrap_binder<T,C:FnOnce(&T,&mutSelf) -> Result<(), fmt::Error>>(
 &mutself,
 value:&ty::Binder<'tcx,T>,
+mode:WrapBinderMode,
 f:C,
 ) -> Result<(), fmt::Error>
 where
 T:TypeFoldable<TyCtxt<'tcx>>,
 {
 let old_region_index = self.region_index;
-let(new_value, _) = self.name_all_regions(value)?;
+let(new_value, _) = self.name_all_regions(value, mode)?;
 f(&new_value,self)?;
 self.region_index = old_region_index;
 self.binder_depth -= 1;
@@ -2877,7 +2911,7 @@ where
 T:Print<'tcx,P> + TypeFoldable<TyCtxt<'tcx>>,
 {
 fnprint(&self,cx:&mutP) -> Result<(),PrintError>{
- cx.in_binder(self)
+ cx.print_in_binder(self)
 }
 }
 

compiler/rustc_symbol_mangling/src/v0.rs

@@ -169,7 +169,7 @@ impl<'tcx> SymbolMangler<'tcx> {
 Ok(())
 }
 
-fnin_binder<T>(
+fnwrap_binder<T>(
 &mutself,
 value:&ty::Binder<'tcx,T>,
 print_value:implFnOnce(&mutSelf,&T) -> Result<(),PrintError>,
@@ -471,7 +471,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
  ty::FnPtr(sig_tys, hdr) => {
 let sig = sig_tys.with(hdr);
 self.push("F");
-self.in_binder(&sig, |cx, sig| {
+self.wrap_binder(&sig, |cx, sig| {
 if sig.safety.is_unsafe(){
  cx.push("U");
 }
@@ -554,7 +554,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
 // [<Trait> [{<Projection>}]] [{<Auto>}]
 // Since any predicates after the first one shouldn't change the binders,
 // just put them all in the binders of the first.
-self.in_binder(&predicates[0], |cx, _| {
+self.wrap_binder(&predicates[0], |cx, _| {
 for predicate in predicates.iter(){
 // It would be nice to be able to validate bound vars here, but
 // projections can actually include bound vars from super traits

compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs

@@ -65,7 +65,9 @@ use rustc_middle::bug;
 use rustc_middle::dep_graph::DepContext;
 use rustc_middle::traits::PatternOriginExpr;
 use rustc_middle::ty::error::{ExpectedFound,TypeError,TypeErrorToStringExt};
-use rustc_middle::ty::print::{PrintError,PrintTraitRefExtas _, with_forced_trimmed_paths};
+use rustc_middle::ty::print::{
+PrintError,PrintTraitRefExtas _,WrapBinderMode, with_forced_trimmed_paths,
+};
 use rustc_middle::ty::{
 self,List,ParamEnv,Region,Ty,TyCtxt,TypeFoldable,TypeSuperVisitable,TypeVisitable,
 TypeVisitableExt,
@@ -835,7 +837,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 let get_lifetimes = |sig| {
 use rustc_hir::def::Namespace;
 let(sig, reg) = ty::print::FmtPrinter::new(self.tcx,Namespace::TypeNS)
-.name_all_regions(sig)
+.name_all_regions(sig,WrapBinderMode::ForAll)
 .unwrap();
 let lts:Vec<String> =
  reg.into_items().map(|(_, kind)| kind.to_string()).into_sorted_stable_ord();

tests/ui/unsafe-binders/type-mismatch.rs

@@ -0,0 +1,9 @@
+#![feature(unsafe_binders)]
+//~^ WARN the feature `unsafe_binders` is incomplete
+
+fnmain(){
+let x:unsafe<> i32 = 0;
+//~^ ERROR mismatched types
+let x:unsafe<'a> &'ai32 = &0;
+//~^ ERROR mismatched types
+}

tests/ui/unsafe-binders/type-mismatch.stderr

@@ -0,0 +1,34 @@
+warning: the feature `unsafe_binders` is incomplete and may not be safe to use and/or cause compiler crashes
+ --> $DIR/type-mismatch.rs:1:12
+ |
+LL | #![feature(unsafe_binders)]
+ | ^^^^^^^^^^^^^^
+ |
+ = note: see issue #130516 <https://github.com/rust-lang/rust/issues/130516> for more information
+ = note: `#[warn(incomplete_features)]` on by default
+
+error[E0308]: mismatched types
+ --> $DIR/type-mismatch.rs:5:27
+ |
+LL | let x: unsafe<> i32 = 0;
+ | ------------ ^ expected `unsafe<> i32`, found integer
+ | |
+ | expected due to this
+ |
+ = note: expected unsafe binder `unsafe<> i32`
+ found type `{integer}`
+
+error[E0308]: mismatched types
+ --> $DIR/type-mismatch.rs:7:33
+ |
+LL | let x: unsafe<'a> &'a i32 = &0;
+ | ------------------ ^^ expected `unsafe<'a> &i32`, found `&{integer}`
+ | |
+ | expected due to this
+ |
+ = note: expected unsafe binder `unsafe<'a> &'a i32`
+ found reference `&{integer}`
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0308`.