Rollup merge of rust-lang#141580 - oli-obk:early-dyn-catches-the-incompat, r=compiler-errors

Use more detailed spans in dyn compat errors within bodies

Within bodies we can employ the full dyn compat check query instead of only doing the minimal hir ty lowerer one. This in turn gives us better spans and also silences many follow-up duplicate or bogus errors.

alternative to rust-lang#141439, tho I think I could turn the delayed bug from that one into a bug now instead of having an error code path.

r? `@compiler-errors`
cc `@fmease`

Author: compiler-errors

compiler/rustc_hir_analysis/src/collect.rs

@@ -31,7 +31,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{self, InferKind, Visitor, VisitorExt, walk_generics};
 use rustc_hir::{self as hir, GenericParamKind, HirId, Node, PreciseCapturingArgKind};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::{DynCompatibilityViolation, ObligationCause};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::util::{Discr, IntTypeExt};
@@ -40,7 +40,7 @@ use rustc_middle::{bug, span_bug};
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
 use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::ObligationCtxt;
+use rustc_trait_selection::traits::{ObligationCtxt, hir_ty_lowering_dyn_compatibility_violations};
 use tracing::{debug, instrument};
 
 use crate::errors;
@@ -625,6 +625,10 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
 
         (input_tys, output_ty)
     }
+
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation> {
+        hir_ty_lowering_dyn_compatibility_violations(self.tcx, trait_def_id)
+    }
 }
 
 /// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.

compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs

@@ -11,7 +11,7 @@ use rustc_middle::ty::{
 };
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility;
-use rustc_trait_selection::traits::{self, hir_ty_lowering_dyn_compatibility_violations};
+use rustc_trait_selection::traits;
 use smallvec::{SmallVec, smallvec};
 use tracing::{debug, instrument};
 
@@ -97,8 +97,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         // to avoid ICEs.
         for (clause, span) in user_written_bounds {
             if let Some(trait_pred) = clause.as_trait_clause() {
-                let violations =
-                    hir_ty_lowering_dyn_compatibility_violations(tcx, trait_pred.def_id());
+                let violations = self.dyn_compatibility_violations(trait_pred.def_id());
                 if !violations.is_empty() {
                     let reported = report_dyn_incompatibility(
                         tcx,

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -33,7 +33,7 @@ use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, AnonConst, GenericArg, GenericArgs, HirId};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::{DynCompatibilityViolation, ObligationCause};
 use rustc_middle::middle::stability::AllowUnstable;
 use rustc_middle::mir::interpret::LitToConstInput;
 use rustc_middle::ty::print::PrintPolyTraitRefExt as _;
@@ -200,6 +200,10 @@ pub trait HirTyLowerer<'tcx> {
     {
         self
     }
+
+    /// Performs minimalistic dyn compat checks outside of bodies, but full within bodies.
+    /// Outside of bodies we could end up in cycles, so we delay most checks to later phases.
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation>;
 }
 
 /// The "qualified self" of an associated item path.

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -14,7 +14,7 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, HirId, ItemLocalMap};
 use rustc_hir_analysis::hir_ty_lowering::{HirTyLowerer, RegionInferReason};
 use rustc_infer::infer;
-use rustc_infer::traits::Obligation;
+use rustc_infer::traits::{DynCompatibilityViolation, Obligation};
 use rustc_middle::ty::{self, Const, Ty, TyCtxt, TypeVisitableExt};
 use rustc_session::Session;
 use rustc_span::{self, DUMMY_SP, ErrorGuaranteed, Ident, Span, sym};
@@ -388,6 +388,10 @@ impl<'tcx> HirTyLowerer<'tcx> for FnCtxt<'_, 'tcx> {
         };
         (input_tys, output_ty)
     }
+
+    fn dyn_compatibility_violations(&self, trait_def_id: DefId) -> Vec<DynCompatibilityViolation> {
+        self.tcx.dyn_compatibility_violations(trait_def_id).to_vec()
+    }
 }
 
 /// The `ty` representation of a user-provided type. Depending on the use-site

tests/ui/async-await/dyn/mut-is-pointer-like.stderr

@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/mut-is-pointer-like.rs:35:16
+  --> $DIR/mut-is-pointer-like.rs:35:29
    |
 LL |         let x: Pin<&mut dyn AsyncTrait<Output = ()>> = f;
-   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>

tests/ui/async-await/dyn/works.stderr

@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:27:16
+  --> $DIR/works.rs:27:21
    |
 LL |         let x: &dyn AsyncTrait = &"hello, world!";
-   |                ^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                     ^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>

tests/ui/async-await/dyn/wrong-size.stderr

@@ -8,10 +8,10 @@ LL | #![feature(async_fn_in_dyn_trait)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/wrong-size.rs:21:12
+  --> $DIR/wrong-size.rs:21:17
    |
 LL |     let x: &dyn AsyncTrait = &"hello, world!";
-   |            ^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
+   |                 ^^^^^^^^^^ `AsyncTrait` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>

tests/ui/async-await/in-trait/dyn-compatibility.stderr

@@ -1,8 +1,8 @@
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility.rs:9:12
+  --> $DIR/dyn-compatibility.rs:9:17
    |
 LL |     let x: &dyn Foo = todo!();
-   |            ^^^^^^^^ `Foo` is not dyn compatible
+   |                 ^^^ `Foo` is not dyn compatible
    |
 note: for a trait to be dyn compatible it needs to allow building a vtable
       for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>

tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.rs

@@ -4,4 +4,5 @@ fn main() {
     let _: &Copy + 'static; //~ ERROR expected a path
     //~^ ERROR is not dyn compatible
     let _: &'static Copy + 'static; //~ ERROR expected a path
+    //~^ ERROR is not dyn compatible
 }

tests/ui/did_you_mean/trait-object-reference-without-parens-suggestion.stderr

@@ -21,16 +21,26 @@ LL |     let _: &'static (Copy + 'static);
    |                     +              +
 
 error[E0038]: the trait `Copy` is not dyn compatible
-  --> $DIR/trait-object-reference-without-parens-suggestion.rs:4:12
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:4:13
    |
 LL |     let _: &Copy + 'static;
-   |            ^^^^^ `Copy` is not dyn compatible
+   |             ^^^^ `Copy` is not dyn compatible
+   |
+   = note: the trait is not dyn compatible because it requires `Self: Sized`
+   = note: for a trait to be dyn compatible it needs to allow building a vtable
+           for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+
+error[E0038]: the trait `Copy` is not dyn compatible
+  --> $DIR/trait-object-reference-without-parens-suggestion.rs:6:21
+   |
+LL |     let _: &'static Copy + 'static;
+   |                     ^^^^ `Copy` is not dyn compatible
    |
    = note: the trait is not dyn compatible because it requires `Self: Sized`
    = note: for a trait to be dyn compatible it needs to allow building a vtable
            for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0038, E0178.
 For more information about an error, try `rustc --explain E0038`.