[BETA] Beta 1.64 backports

compiler/rustc_errors/src/diagnostic.rs

@@ -40,6 +40,26 @@ pub trait IntoDiagnosticArg {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static>;
 }
 
+pub struct DiagnosticArgFromDisplay<'a>(pub &'a dyn fmt::Display);
+
+impl IntoDiagnosticArg for DiagnosticArgFromDisplay<'_> {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        self.0.to_string().into_diagnostic_arg()
+    }
+}
+
+impl<'a> From<&'a dyn fmt::Display> for DiagnosticArgFromDisplay<'a> {
+    fn from(t: &'a dyn fmt::Display) -> Self {
+        DiagnosticArgFromDisplay(t)
+    }
+}
+
+impl<'a, T: fmt::Display> From<&'a T> for DiagnosticArgFromDisplay<'a> {
+    fn from(t: &'a T) -> Self {
+        DiagnosticArgFromDisplay(t)
+    }
+}
+
 macro_rules! into_diagnostic_arg_using_display {
     ($( $ty:ty ),+ $(,)?) => {
         $(

compiler/rustc_errors/src/lib.rs

@@ -371,8 +371,8 @@ impl fmt::Display for ExplicitBug {
 impl error::Error for ExplicitBug {}
 
 pub use diagnostic::{
-    AddSubdiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgValue, DiagnosticId,
-    DiagnosticStyledString, IntoDiagnosticArg, SubDiagnostic,
+    AddSubdiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgFromDisplay,
+    DiagnosticArgValue, DiagnosticId, DiagnosticStyledString, IntoDiagnosticArg, SubDiagnostic,
 };
 pub use diagnostic_builder::{DiagnosticBuilder, EmissionGuarantee, LintDiagnosticBuilder};
 use std::backtrace::Backtrace;

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -40,23 +40,25 @@ pub struct OpaqueTypeDecl<'tcx> {
 }
 
 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
-    pub fn replace_opaque_types_with_inference_vars(
+    /// This is a backwards compatibility hack to prevent breaking changes from
+    /// lazy TAIT around RPIT handling.
+    pub fn replace_opaque_types_with_inference_vars<T: TypeFoldable<'tcx>>(
         &self,
-        ty: Ty<'tcx>,
+        value: T,
         body_id: HirId,
         span: Span,
         param_env: ty::ParamEnv<'tcx>,
-    ) -> InferOk<'tcx, Ty<'tcx>> {
-        if !ty.has_opaque_types() {
-            return InferOk { value: ty, obligations: vec![] };
+    ) -> InferOk<'tcx, T> {
+        if !value.has_opaque_types() {
+            return InferOk { value, obligations: vec![] };
         }
         let mut obligations = vec![];
         let replace_opaque_type = |def_id: DefId| {
             def_id
                 .as_local()
                 .map_or(false, |def_id| self.opaque_type_origin(def_id, span).is_some())
         };
-        let value = ty.fold_with(&mut ty::fold::BottomUpFolder {
+        let value = value.fold_with(&mut ty::fold::BottomUpFolder {
             tcx: self.tcx,
             lt_op: |lt| lt,
             ct_op: |ct| ct,

compiler/rustc_privacy/src/errors.rs

@@ -1,3 +1,4 @@
+use rustc_errors::DiagnosticArgFromDisplay;
 use rustc_macros::{LintDiagnostic, SessionDiagnostic, SessionSubdiagnostic};
 use rustc_span::{Span, Symbol};
 
@@ -35,7 +36,7 @@ pub struct ItemIsPrivate<'a> {
     #[label]
     pub span: Span,
     pub kind: &'a str,
-    pub descr: String,
+    pub descr: DiagnosticArgFromDisplay<'a>,
 }
 
 #[derive(SessionDiagnostic)]
@@ -55,7 +56,7 @@ pub struct InPublicInterfaceTraits<'a> {
     pub span: Span,
     pub vis_descr: &'static str,
     pub kind: &'a str,
-    pub descr: String,
+    pub descr: DiagnosticArgFromDisplay<'a>,
     #[label(privacy::visibility_label)]
     pub vis_span: Span,
 }
@@ -69,7 +70,7 @@ pub struct InPublicInterface<'a> {
     pub span: Span,
     pub vis_descr: &'static str,
     pub kind: &'a str,
-    pub descr: String,
+    pub descr: DiagnosticArgFromDisplay<'a>,
     #[label(privacy::visibility_label)]
     pub vis_span: Span,
 }
@@ -78,7 +79,7 @@ pub struct InPublicInterface<'a> {
 #[lint(privacy::from_private_dep_in_public_interface)]
 pub struct FromPrivateDependencyInPublicInterface<'a> {
     pub kind: &'a str,
-    pub descr: String,
+    pub descr: DiagnosticArgFromDisplay<'a>,
     pub krate: Symbol,
 }
 
@@ -87,5 +88,5 @@ pub struct FromPrivateDependencyInPublicInterface<'a> {
 pub struct PrivateInPublicLint<'a> {
     pub vis_descr: &'static str,
     pub kind: &'a str,
-    pub descr: String,
+    pub descr: DiagnosticArgFromDisplay<'a>,
 }

compiler/rustc_privacy/src/lib.rs

@@ -1079,11 +1079,7 @@ impl<'tcx> TypePrivacyVisitor<'tcx> {
     fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display) -> bool {
         let is_error = !self.item_is_accessible(def_id);
         if is_error {
-            self.tcx.sess.emit_err(ItemIsPrivate {
-                span: self.span,
-                kind,
-                descr: descr.to_string(),
-            });
+            self.tcx.sess.emit_err(ItemIsPrivate { span: self.span, kind, descr: descr.into() });
         }
         is_error
     }
@@ -1255,7 +1251,9 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
                 };
                 let kind = kind.descr(def_id);
                 let _ = match name {
-                    Some(name) => sess.emit_err(ItemIsPrivate { span, kind, descr: name }),
+                    Some(name) => {
+                        sess.emit_err(ItemIsPrivate { span, kind, descr: (&name).into() })
+                    }
                     None => sess.emit_err(UnnamedItemIsPrivate { span, kind }),
                 };
                 return;
@@ -1723,7 +1721,7 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                 self.tcx.def_span(self.item_def_id.to_def_id()),
                 FromPrivateDependencyInPublicInterface {
                     kind,
-                    descr: descr.to_string(),
+                    descr: descr.into(),
                     krate: self.tcx.crate_name(def_id.krate),
                 },
             );
@@ -1750,7 +1748,6 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                 }
             };
             let span = self.tcx.def_span(self.item_def_id.to_def_id());
-            let descr = descr.to_string();
             if self.has_old_errors
                 || self.in_assoc_ty
                 || self.tcx.resolutions(()).has_pub_restricted
@@ -1761,15 +1758,15 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                         span,
                         vis_descr,
                         kind,
-                        descr,
+                        descr: descr.into(),
                         vis_span,
                     });
                 } else {
                     self.tcx.sess.emit_err(InPublicInterface {
                         span,
                         vis_descr,
                         kind,
-                        descr,
+                        descr: descr.into(),
                         vis_span,
                     });
                 }
@@ -1778,7 +1775,7 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                     lint::builtin::PRIVATE_IN_PUBLIC,
                     hir_id,
                     span,
-                    PrivateInPublicLint { vis_descr, kind, descr },
+                    PrivateInPublicLint { vis_descr, kind, descr: descr.into() },
                 );
             }
         }

compiler/rustc_trait_selection/src/traits/project.rs

@@ -252,10 +252,20 @@ fn project_and_unify_type<'cx, 'tcx>(
         Err(InProgress) => return ProjectAndUnifyResult::Recursive,
     };
     debug!(?normalized, ?obligations, "project_and_unify_type result");
-    match infcx
-        .at(&obligation.cause, obligation.param_env)
-        .eq(normalized, obligation.predicate.term)
-    {
+    let actual = obligation.predicate.term;
+    // For an example where this is neccessary see src/test/ui/impl-trait/nested-return-type2.rs
+    // This allows users to omit re-mentioning all bounds on an associated type and just use an
+    // `impl Trait` for the assoc type to add more bounds.
+    let InferOk { value: actual, obligations: new } =
+        selcx.infcx().replace_opaque_types_with_inference_vars(
+            actual,
+            obligation.cause.body_id,
+            obligation.cause.span,
+            obligation.param_env,
+        );
+    obligations.extend(new);
+
+    match infcx.at(&obligation.cause, obligation.param_env).eq(normalized, actual) {
         Ok(InferOk { obligations: inferred_obligations, value: () }) => {
             obligations.extend(inferred_obligations);
             ProjectAndUnifyResult::Holds(obligations)

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -1761,13 +1761,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             .filter_map(|seg| seg.args.as_ref())
                             .flat_map(|a| a.args.iter())
                         {
-                            if let hir::GenericArg::Type(hir_ty) = &arg {
-                                let ty = self.resolve_vars_if_possible(
-                                    self.typeck_results.borrow().node_type(hir_ty.hir_id),
-                                );
-                                if ty == predicate.self_ty() {
-                                    error.obligation.cause.span = hir_ty.span;
-                                }
+                            if let hir::GenericArg::Type(hir_ty) = &arg
+                                && let Some(ty) =
+                                    self.typeck_results.borrow().node_type_opt(hir_ty.hir_id)
+                                && self.resolve_vars_if_possible(ty) == predicate.self_ty()
+                            {
+                                error.obligation.cause.span = hir_ty.span;
+                                break;
                             }
                         }
                     }

src/test/ui/argument-suggestions/issue-100154.rs

@@ -0,0 +1,7 @@
+fn foo(i: impl std::fmt::Display) {}
+
+fn main() {
+    foo::<()>(());
+    //~^ ERROR this function takes 0 generic arguments but 1 generic argument was supplied
+    //~| ERROR `()` doesn't implement `std::fmt::Display`
+}

src/test/ui/argument-suggestions/issue-100154.stderr

@@ -0,0 +1,35 @@
+error[E0107]: this function takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/issue-100154.rs:4:5
+   |
+LL |     foo::<()>(());
+   |     ^^^------ help: remove these generics
+   |     |
+   |     expected 0 generic arguments
+   |
+note: function defined here, with 0 generic parameters
+  --> $DIR/issue-100154.rs:1:4
+   |
+LL | fn foo(i: impl std::fmt::Display) {}
+   |    ^^^
+   = note: `impl Trait` cannot be explicitly specified as a generic argument
+
+error[E0277]: `()` doesn't implement `std::fmt::Display`
+  --> $DIR/issue-100154.rs:4:15
+   |
+LL |     foo::<()>(());
+   |     --------- ^^ `()` cannot be formatted with the default formatter
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: the trait `std::fmt::Display` is not implemented for `()`
+   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
+note: required by a bound in `foo`
+  --> $DIR/issue-100154.rs:1:16
+   |
+LL | fn foo(i: impl std::fmt::Display) {}
+   |                ^^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0107, E0277.
+For more information about an error, try `rustc --explain E0107`.

src/test/ui/impl-trait/issues/issue-86800.rs

@@ -1,6 +1,14 @@
 #![feature(type_alias_impl_trait)]
 
 // edition:2021
+// unset-rustc-env:RUST_BACKTRACE
+// compile-flags:-Z treat-err-as-bug=1
+// error-pattern:stack backtrace:
+// failure-status:101
+// normalize-stderr-test "note: .*" -> ""
+// normalize-stderr-test "thread 'rustc' .*" -> ""
+// normalize-stderr-test " +[0-9]+:.*\n" -> ""
+// normalize-stderr-test " +at .*\n" -> ""
 
 use std::future::Future;
 
@@ -23,7 +31,6 @@ struct Context {
 type TransactionResult<O> = Result<O, ()>;
 
 type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
-//~^ ERROR unconstrained opaque type
 
 fn execute_transaction_fut<'f, F, O>(
     f: F,

src/test/ui/impl-trait/issues/issue-86800.stderr

@@ -1,10 +1,19 @@
-error: unconstrained opaque type
-  --> $DIR/issue-86800.rs:25:34
-   |
-LL | type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
-   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `TransactionFuture` must be used in combination with a concrete type within the same module
 
-error: aborting due to previous error
+stack backtrace:
 
+error: internal compiler error: unexpected panic
+
+
+
+
+
+
+
+
+
+query stack during panic:
+#0 [mir_borrowck] borrow-checking `execute_transaction_fut`
+#1 [type_of] computing type of `TransactionFuture::{opaque#0}`
+#2 [check_mod_item_types] checking item types in top-level module
+#3 [analysis] running analysis passes on this crate
+end of query stack

src/test/ui/impl-trait/nested-return-type2-tait.rs

@@ -1,5 +1,7 @@
 #![feature(type_alias_impl_trait)]
 
+// check-pass
+
 trait Duh {}
 
 impl Duh for i32 {}
@@ -17,13 +19,13 @@ impl<R: Duh, F: FnMut() -> R> Trait for F {
 
 type Sendable = impl Send;
 
-// The `Sendable` here is then later compared against the inference var
-// created, causing the inference var to be set to `Sendable` instead of
+// The `Sendable` here is converted to an inference var and then later compared
+// against the inference var created, causing the inference var to be set to
+// the hidden type of `Sendable` instead of
 // the hidden type. We already have obligations registered on the inference
 // var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
-// type does not implement `Duh`, even if its hidden type does. So we error out.
+// type does not implement `Duh`, but if its hidden type does.
 fn foo() -> impl Trait<Assoc = Sendable> {
-    //~^ ERROR `Sendable: Duh` is not satisfied
     || 42
 }
 

src/test/ui/impl-trait/nested-return-type2-tait2.rs

@@ -24,8 +24,8 @@ type Traitable = impl Trait<Assoc = Sendable>;
 // var to make it uphold the `: Duh` bound on `Trait::Assoc`. The opaque
 // type does not implement `Duh`, even if its hidden type does. So we error out.
 fn foo() -> Traitable {
-    //~^ ERROR `Sendable: Duh` is not satisfied
     || 42
+    //~^ ERROR `Sendable: Duh` is not satisfied
 }
 
 fn main() {

src/test/ui/impl-trait/nested-return-type2-tait2.stderr

@@ -1,11 +1,11 @@
 error[E0277]: the trait bound `Sendable: Duh` is not satisfied
-  --> $DIR/nested-return-type2-tait2.rs:26:13
+  --> $DIR/nested-return-type2-tait2.rs:27:5
    |
-LL | fn foo() -> Traitable {
-   |             ^^^^^^^^^ the trait `Duh` is not implemented for `Sendable`
+LL |     || 42
+   |     ^^^^^ the trait `Duh` is not implemented for `Sendable`
    |
    = help: the trait `Duh` is implemented for `i32`
-note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait2.rs:28:5: 28:7]`
+note: required because of the requirements on the impl of `Trait` for `[closure@$DIR/nested-return-type2-tait2.rs:27:5: 27:7]`
   --> $DIR/nested-return-type2-tait2.rs:14:31
    |
 LL | impl<R: Duh, F: FnMut() -> R> Trait for F {