Unrolled build for rust-lang#135378

Rollup merge of rust-lang#135378 - compiler-errors:unnecessary-stashing, r=chenyukang

Remove a bunch of diagnostic stashing that doesn't do anything

rust-lang#121669 removed a bunch of conditional diagnostic stashing/canceling, but left around the `steal` calls which just emitted the error eagerly instead of canceling the diagnostic. I think that these no-op `steal` calls don't do much and are confusing to encounter, so let's remove them.

The net effect is:
1. We emit more duplicated errors, since stashing has the side effect of duplicating diagnostics. This is not a big deal, since outside of `-Zdeduplicate-diagnostics=no`, the errors are already being deduplicated by the compiler.
2. It changes the order of diagnostics, since we're no longer stashing and then later stealing the errors. I don't think this matters much for the changes that the UI test suite manifests, and it makes these errors less order dependent.

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -152,7 +152,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         let (Ok(e) | Err(e)) = prev
                             .build_mismatch_error(
                                 &OpaqueHiddenType { ty, span: concrete_type.span },
-                                opaque_type_key.def_id,
                                 infcx.tcx,
                             )
                             .map(|d| d.emit());

compiler/rustc_errors/src/lib.rs

@@ -566,9 +566,7 @@ pub enum StashKey {
     /// FRU syntax
     MaybeFruTypo,
     CallAssocMethod,
-    TraitMissingMethod,
     AssociatedTypeSuggestion,
-    OpaqueHiddenTypeMismatch,
     MaybeForgetReturn,
     /// Query cycle detected, stashing in favor of a better error.
     Cycle,

compiler/rustc_hir_analysis/src/check/check.rs

@@ -575,7 +575,7 @@ fn sanity_check_found_hidden_type<'tcx>(
     } else {
         let span = tcx.def_span(key.def_id);
         let other = ty::OpaqueHiddenType { ty: hidden_ty, span };
-        Err(ty.build_mismatch_error(&other, key.def_id, tcx)?.emit())
+        Err(ty.build_mismatch_error(&other, tcx)?.emit())
     }
 }
 

compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs

@@ -1,4 +1,3 @@
-use rustc_errors::StashKey;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{self, Visitor};
@@ -45,7 +44,7 @@ pub(super) fn find_opaque_ty_constraints_for_impl_trait_in_assoc_type(
         if !hidden.ty.references_error() {
             for concrete_type in locator.typeck_types {
                 if concrete_type.ty != tcx.erase_regions(hidden.ty) {
-                    if let Ok(d) = hidden.build_mismatch_error(&concrete_type, def_id, tcx) {
+                    if let Ok(d) = hidden.build_mismatch_error(&concrete_type, tcx) {
                         d.emit();
                     }
                 }
@@ -121,7 +120,7 @@ pub(super) fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: Local
         if !hidden.ty.references_error() {
             for concrete_type in locator.typeck_types {
                 if concrete_type.ty != tcx.erase_regions(hidden.ty) {
-                    if let Ok(d) = hidden.build_mismatch_error(&concrete_type, def_id, tcx) {
+                    if let Ok(d) = hidden.build_mismatch_error(&concrete_type, tcx) {
                         d.emit();
                     }
                 }
@@ -285,9 +284,8 @@ impl TaitConstraintLocator<'_> {
             debug!(?concrete_type, "found constraint");
             if let Some(prev) = &mut self.found {
                 if concrete_type.ty != prev.ty {
-                    let (Ok(guar) | Err(guar)) = prev
-                        .build_mismatch_error(&concrete_type, self.def_id, self.tcx)
-                        .map(|d| d.emit());
+                    let (Ok(guar) | Err(guar)) =
+                        prev.build_mismatch_error(&concrete_type, self.tcx).map(|d| d.emit());
                     prev.ty = Ty::new_error(self.tcx, guar);
                 }
             } else {
@@ -361,11 +359,8 @@ pub(super) fn find_opaque_ty_constraints_for_rpit<'tcx>(
             );
             if let Some(prev) = &mut hir_opaque_ty {
                 if concrete_type.ty != prev.ty {
-                    if let Ok(d) = prev.build_mismatch_error(&concrete_type, def_id, tcx) {
-                        d.stash(
-                            tcx.def_span(opaque_type_key.def_id),
-                            StashKey::OpaqueHiddenTypeMismatch,
-                        );
+                    if let Ok(d) = prev.build_mismatch_error(&concrete_type, tcx) {
+                        d.emit();
                     }
                 }
             } else {
@@ -435,9 +430,7 @@ impl RpitConstraintChecker<'_> {
             debug!(?concrete_type, "found constraint");
 
             if concrete_type.ty != self.found.ty {
-                if let Ok(d) =
-                    self.found.build_mismatch_error(&concrete_type, self.def_id, self.tcx)
-                {
+                if let Ok(d) = self.found.build_mismatch_error(&concrete_type, self.tcx) {
                     d.emit();
                 }
             }

compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

@@ -96,7 +96,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 s1.append(s2);
                 sugg.cancel();
             }
-            diag.stash(self_ty.span, StashKey::TraitMissingMethod)
+            Some(diag.emit())
         } else {
             tcx.node_span_lint(BARE_TRAIT_OBJECTS, self_ty.hir_id, self_ty.span, |lint| {
                 lint.primary_message("trait objects without an explicit `dyn` are deprecated");

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -3,7 +3,7 @@ use std::slice;
 
 use rustc_abi::FieldIdx;
 use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan, StashKey};
+use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan};
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
@@ -806,17 +806,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let item_name = item_segment.ident;
         let result = self
             .resolve_fully_qualified_call(span, item_name, ty.normalized, qself.span, hir_id)
-            .map(|r| {
-                // lint bare trait if the method is found in the trait
-                if span.edition().at_least_rust_2021() {
-                    self.dcx().try_steal_modify_and_emit_err(
-                        qself.span,
-                        StashKey::TraitMissingMethod,
-                        |_err| {},
-                    );
-                }
-                r
-            })
             .or_else(|error| {
                 let guar = self
                     .dcx()
@@ -840,17 +829,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                 }
 
-                // Emit the diagnostic for bare traits. (We used to cancel for slightly better
-                // error messages, but cancelling stashed diagnostics is no longer allowed because
-                // it causes problems when tracking whether errors have actually occurred.)
-                if span.edition().at_least_rust_2021() {
-                    self.dcx().try_steal_modify_and_emit_err(
-                        qself.span,
-                        StashKey::TraitMissingMethod,
-                        |_err| {},
-                    );
-                }
-
                 if item_name.name != kw::Empty {
                     self.report_method_error(
                         hir_id,

compiler/rustc_hir_typeck/src/writeback.rs

@@ -5,7 +5,7 @@
 use std::mem;
 
 use rustc_data_structures::unord::ExtendUnord;
-use rustc_errors::{ErrorGuaranteed, StashKey};
+use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::HirId;
 use rustc_hir::intravisit::{self, Visitor};
@@ -582,15 +582,8 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
                 && last_opaque_ty.ty != hidden_type.ty
             {
                 assert!(!self.fcx.next_trait_solver());
-                if let Ok(d) = hidden_type.build_mismatch_error(
-                    &last_opaque_ty,
-                    opaque_type_key.def_id,
-                    self.tcx(),
-                ) {
-                    d.stash(
-                        self.tcx().def_span(opaque_type_key.def_id),
-                        StashKey::OpaqueHiddenTypeMismatch,
-                    );
+                if let Ok(d) = hidden_type.build_mismatch_error(&last_opaque_ty, self.tcx()) {
+                    d.emit();
                 }
             }
         }

compiler/rustc_middle/src/ty/mod.rs

@@ -32,7 +32,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
-use rustc_errors::{Diag, ErrorGuaranteed, StashKey};
+use rustc_errors::{Diag, ErrorGuaranteed};
 use rustc_hir::LangItem;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
@@ -782,18 +782,8 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
     pub fn build_mismatch_error(
         &self,
         other: &Self,
-        opaque_def_id: LocalDefId,
         tcx: TyCtxt<'tcx>,
     ) -> Result<Diag<'tcx>, ErrorGuaranteed> {
-        // We used to cancel here for slightly better error messages, but
-        // cancelling stashed diagnostics is no longer allowed because it
-        // causes problems when tracking whether errors have actually
-        // occurred.
-        tcx.sess.dcx().try_steal_modify_and_emit_err(
-            tcx.def_span(opaque_def_id),
-            StashKey::OpaqueHiddenTypeMismatch,
-            |_err| {},
-        );
         (self.ty, other.ty).error_reported()?;
         // Found different concrete types for the opaque type.
         let sub_diag = if self.span == other.span {

tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs

@@ -15,6 +15,7 @@ fn f<T>(
      }],
 ) -> impl Iterator<Item = SubAssign> {
 //~^ ERROR expected a type, found a trait
+//~| ERROR expected a type, found a trait
 //~| ERROR `()` is not an iterator
 }
 

tests/ui/const-generics/generic_const_exprs/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.stderr

@@ -16,20 +16,28 @@ help: you might be missing a type parameter
 LL | fn f<T, F>(
    |       +++
 
-error[E0277]: `()` is not an iterator
-  --> $DIR/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs:16:6
+error[E0782]: expected a type, found a trait
+  --> $DIR/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs:16:27
    |
 LL | ) -> impl Iterator<Item = SubAssign> {
-   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
+   |                           ^^^^^^^^^
    |
-   = help: the trait `Iterator` is not implemented for `()`
+help: you can add the `dyn` keyword if you want a trait object
+   |
+LL | ) -> impl Iterator<Item = dyn SubAssign> {
+   |                           +++
+help: you might have meant to write a bound here
+   |
+LL | ) -> impl Iterator<Item: SubAssign> {
+   |                        ~
 
 error[E0782]: expected a type, found a trait
   --> $DIR/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs:16:27
    |
 LL | ) -> impl Iterator<Item = SubAssign> {
    |                           ^^^^^^^^^
    |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 help: you can add the `dyn` keyword if you want a trait object
    |
 LL | ) -> impl Iterator<Item = dyn SubAssign> {
@@ -39,7 +47,15 @@ help: you might have meant to write a bound here
 LL | ) -> impl Iterator<Item: SubAssign> {
    |                        ~
 
-error: aborting due to 3 previous errors
+error[E0277]: `()` is not an iterator
+  --> $DIR/expected-type-of-closure-body-to-be-a-closure-or-coroutine-ice-113776.rs:16:6
+   |
+LL | ) -> impl Iterator<Item = SubAssign> {
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `()` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `()`
+
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0277, E0412, E0782.
 For more information about an error, try `rustc --explain E0277`.

tests/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.edition2021.stderr

@@ -9,6 +9,18 @@ help: you can add the `dyn` keyword if you want a trait object
 LL | fn ice() -> impl AsRef<dyn Fn(&())> {
    |                        +++
 
-error: aborting due to 1 previous error
+error[E0782]: expected a type, found a trait
+  --> $DIR/generic-with-implicit-hrtb-without-dyn.rs:6:24
+   |
+LL | fn ice() -> impl AsRef<Fn(&())> {
+   |                        ^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: you can add the `dyn` keyword if you want a trait object
+   |
+LL | fn ice() -> impl AsRef<dyn Fn(&())> {
+   |                        +++
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0782`.

tests/ui/impl-trait/generic-with-implicit-hrtb-without-dyn.rs

@@ -6,6 +6,7 @@
 fn ice() -> impl AsRef<Fn(&())> {
     //[edition2015]~^ ERROR: the trait bound `(): AsRef<(dyn for<'a> Fn(&'a ()) + 'static)>` is not satisfied [E0277]
     //[edition2021]~^^ ERROR: expected a type, found a trait [E0782]
+    //[edition2021]~| ERROR: expected a type, found a trait [E0782]
     todo!()
 }
 

tests/ui/impl-trait/issue-99073-2.stderr

@@ -1,12 +1,3 @@
-error[E0792]: expected generic type parameter, found `i32`
-  --> $DIR/issue-99073-2.rs:9:22
-   |
-LL | fn test<T: Display>(t: T, recurse: bool) -> impl Display {
-   |         - this generic parameter must be used with a generic type parameter
-LL |     let f = || {
-LL |         let i: u32 = test::<i32>(-1, false);
-   |                      ^^^^^^^^^^^^^^^^^^^^^^
-
 error: concrete type differs from previous defining opaque type use
   --> $DIR/issue-99073-2.rs:9:22
    |
@@ -19,6 +10,15 @@ note: previous use here
 LL | fn test<T: Display>(t: T, recurse: bool) -> impl Display {
    |                                             ^^^^^^^^^^^^
 
+error[E0792]: expected generic type parameter, found `i32`
+  --> $DIR/issue-99073-2.rs:9:22
+   |
+LL | fn test<T: Display>(t: T, recurse: bool) -> impl Display {
+   |         - this generic parameter must be used with a generic type parameter
+LL |     let f = || {
+LL |         let i: u32 = test::<i32>(-1, false);
+   |                      ^^^^^^^^^^^^^^^^^^^^^^
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0792`.

tests/ui/impl-trait/issue-99073.stderr

@@ -1,11 +1,3 @@
-error[E0792]: expected generic type parameter, found `&F`
-  --> $DIR/issue-99073.rs:6:11
-   |
-LL | fn fix<F: Fn(G), G: Fn()>(f: F) -> impl Fn() {
-   |        - this generic parameter must be used with a generic type parameter
-LL |   move || f(fix(&f))
-   |           ^^^^^^^^^^
-
 error: concrete type differs from previous defining opaque type use
   --> $DIR/issue-99073.rs:6:13
    |
@@ -18,6 +10,14 @@ note: previous use here
 LL | fn fix<F: Fn(G), G: Fn()>(f: F) -> impl Fn() {
    |                                    ^^^^^^^^^
 
+error[E0792]: expected generic type parameter, found `&F`
+  --> $DIR/issue-99073.rs:6:11
+   |
+LL | fn fix<F: Fn(G), G: Fn()>(f: F) -> impl Fn() {
+   |        - this generic parameter must be used with a generic type parameter
+LL |   move || f(fix(&f))
+   |           ^^^^^^^^^^
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0792`.

tests/ui/impl-trait/multiple-defining-usages-in-body.stderr

@@ -1,15 +1,3 @@
-warning: function cannot return without recursing
-  --> $DIR/multiple-defining-usages-in-body.rs:4:1
-   |
-LL | fn foo<T: Trait, U: Trait>() -> impl Trait {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
-LL |
-LL |     let a: T = foo::<T, U>();
-   |                ------------- recursive call site
-   |
-   = help: a `loop` may express intention better if this is on purpose
-   = note: `#[warn(unconditional_recursion)]` on by default
-
 error: concrete type differs from previous defining opaque type use
   --> $DIR/multiple-defining-usages-in-body.rs:8:16
    |
@@ -22,5 +10,17 @@ note: previous use here
 LL |     let a: T = foo::<T, U>();
    |                ^^^^^^^^^^^^^
 
+warning: function cannot return without recursing
+  --> $DIR/multiple-defining-usages-in-body.rs:4:1
+   |
+LL | fn foo<T: Trait, U: Trait>() -> impl Trait {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
+LL |
+LL |     let a: T = foo::<T, U>();
+   |                ------------- recursive call site
+   |
+   = help: a `loop` may express intention better if this is on purpose
+   = note: `#[warn(unconditional_recursion)]` on by default
+
 error: aborting due to 1 previous error; 1 warning emitted