Report a specialized error when a 'static obligation comes from an impl dyn Trait

estebank · estebank · commit 5b76e776a96f · 2024-02-19T00:44:09.000Z
```text
error: lifetime may not live long enough
  --&gt; $DIR/static-impl-obligation.rs:8:27
   |
LL |     fn bar&lt;'a&gt;(x: &amp;'a &amp;'a u32) {
   |            -- lifetime `'a` defined here
LL |         let y: &amp;dyn Foo = x;
   |                           ^ cast requires that `'a` must outlive `'static`
LL |         y.hello();
   |         --------- calling this method introduces a `'static` lifetime requirement
   |
help: relax the implicit `'static` bound on the impl
   |
LL |     impl dyn Foo + '_ {
   |                  ++++
```
```text
error: lifetime may not live long enough
  --&gt; $DIR/static-impl-obligation.rs:173:27
   |
LL |     fn bar&lt;'a&gt;(x: &amp;'a &amp;'a u32) {
   |            -- lifetime `'a` defined here
LL |         let y: &amp;dyn Foo = x;
   |                           ^ cast requires that `'a` must outlive `'static`
LL |         y.hello();
   |         --------- calling this method introduces a `'static` lifetime requirement
   |
note: the `impl` on `(dyn p::Foo + 'static)` has `'static` lifetime requirements
  --&gt; $DIR/static-impl-obligation.rs:169:20
   |
LL |     impl dyn Foo + 'static where Self: 'static {
   |                    ^^^^^^^             ^^^^^^^
LL |         fn hello(&amp;self) where Self: 'static {}
   |                                     ^^^^^^^
```
diff --git a/compiler/rustc_borrowck/Cargo.toml b/compiler/rustc_borrowck/Cargo.toml
@@ -8,6 +8,7 @@ edition = "2021"
 either = "1.5.0"
 itertools = "0.11"
 polonius-engine = "0.13.0"
+rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -2051,6 +2051,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         CRATE_DEF_ID.to_def_id(),
                         predicate_span,
                     ))
+                } else if let ConstraintCategory::CallArgument(Some(fn_def)) = constraint.category {
+                    Some(ObligationCauseCode::MethodCallConstraint(fn_def, constraint.span))
                 } else {
                     None
                 }
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -100,7 +100,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         locations: Locations,
     ) {
         for (predicate, span) in instantiated_predicates {
-            debug!(?predicate);
+            debug!(?span, ?predicate);
             let category = ConstraintCategory::Predicate(span);
             let predicate = self.normalize_with_category(predicate, locations, category);
             self.prove_predicate(predicate, locations, category);
diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -8,7 +8,7 @@ use rustc_middle::mir::{ClosureOutlivesSubject, ClosureRegionRequirements, Const
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::{self, GenericArgKind, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::Span;
 use rustc_trait_selection::solve::deeply_normalize;
 use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
 use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
@@ -183,7 +183,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
 
                         // we don't actually use this for anything, but
                         // the `TypeOutlives` code needs an origin.
-                        let origin = infer::RelateParamBound(DUMMY_SP, t1, None);
+                        let origin = infer::RelateParamBound(self.span, t1, None);
 
                         TypeOutlives::new(
                             &mut *self,
diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
@@ -10,7 +10,7 @@ use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::query::OutlivesBound;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::{self, RegionVid, Ty, TypeVisitableExt};
-use rustc_span::{ErrorGuaranteed, DUMMY_SP};
+use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::solve::deeply_normalize;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::query::type_op::{self, TypeOp};
@@ -269,7 +269,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
             debug!("build: input_or_output={:?}", ty);
             // We add implied bounds from both the unnormalized and normalized ty.
             // See issue #87748
-            let constraints_unnorm = self.add_implied_bounds(ty);
+            let constraints_unnorm = self.add_implied_bounds(ty, span);
             if let Some(c) = constraints_unnorm {
                 constraints.push(c)
             }
@@ -299,7 +299,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
             // ```
             // Both &Self::Bar and &() are WF
             if ty != norm_ty {
-                let constraints_norm = self.add_implied_bounds(norm_ty);
+                let constraints_norm = self.add_implied_bounds(norm_ty, span);
                 if let Some(c) = constraints_norm {
                     constraints.push(c)
                 }
@@ -323,7 +323,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
 
                 // We currently add implied bounds from the normalized ty only.
                 // This is more conservative and matches wfcheck behavior.
-                let c = self.add_implied_bounds(norm_ty);
+                let c = self.add_implied_bounds(norm_ty, span);
                 constraints.extend(c);
             }
         }
@@ -361,11 +361,15 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
     /// the same time, compute and add any implied bounds that come
     /// from this local.
     #[instrument(level = "debug", skip(self))]
-    fn add_implied_bounds(&mut self, ty: Ty<'tcx>) -> Option<&'tcx QueryRegionConstraints<'tcx>> {
+    fn add_implied_bounds(
+        &mut self,
+        ty: Ty<'tcx>,
+        span: Span,
+    ) -> Option<&'tcx QueryRegionConstraints<'tcx>> {
         let TypeOpOutput { output: bounds, constraints, .. } = self
             .param_env
             .and(type_op::implied_outlives_bounds::ImpliedOutlivesBounds { ty })
-            .fully_perform(self.infcx, DUMMY_SP)
+            .fully_perform(self.infcx, span)
             .map_err(|_: ErrorGuaranteed| debug!("failed to compute implied bounds {:?}", ty))
             .ok()?;
         debug!(?bounds, ?constraints);
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -37,7 +37,7 @@ use rustc_mir_dataflow::points::DenseLocationMap;
 use rustc_span::def_id::CRATE_DEF_ID;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::sym;
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::Span;
 use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints;
 use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
@@ -1014,7 +1014,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     ) -> Self {
         let mut checker = Self {
             infcx,
-            last_span: DUMMY_SP,
+            last_span: body.span,
             body,
             user_type_annotations: &body.user_type_annotations,
             param_env,
@@ -2766,7 +2766,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 self.param_env,
                 self.known_type_outlives_obligations,
                 locations,
-                DUMMY_SP,                   // irrelevant; will be overridden.
+                self.body.span,             // irrelevant; will be overridden.
                 ConstraintCategory::Boring, // same as above.
                 self.borrowck_context.constraints,
             )
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
@@ -1630,7 +1630,7 @@ fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
 #[instrument(level = "debug", skip(tcx))]
 fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
     let mut result = tcx.explicit_predicates_of(def_id);
-    debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
+    debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result);
     let inferred_outlives = tcx.inferred_outlives_of(def_id);
     if !inferred_outlives.is_empty() {
         debug!(
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -405,7 +405,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// will instantiate fresh inference variables for each canonical
     /// variable instead. Therefore, the result of this method must be
     /// properly unified
-    #[instrument(level = "debug", skip(self, cause, param_env))]
+    #[instrument(level = "debug", skip(self, param_env))]
     fn query_response_instantiation_guess<R>(
         &self,
         cause: &ObligationCause<'tcx>,
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
@@ -451,6 +451,9 @@ pub enum ObligationCauseCode<'tcx> {
 
     /// Obligations emitted during the normalization of a weak type alias.
     TypeAlias(InternedObligationCauseCode<'tcx>, Span, DefId),
+
+    /// During borrowck we've found a method call that could have introduced a lifetime requirement.
+    MethodCallConstraint(Ty<'tcx>, Span),
 }
 
 /// Whether a value can be extracted into a const.
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2683,6 +2683,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             | ObligationCauseCode::MethodReceiver
             | ObligationCauseCode::ReturnNoExpression
             | ObligationCauseCode::UnifyReceiver(..)
+            | ObligationCauseCode::MethodCallConstraint(..)
             | ObligationCauseCode::MiscObligation
             | ObligationCauseCode::WellFormed(..)
             | ObligationCauseCode::MatchImpl(..)
diff --git a/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs b/compiler/rustc_trait_selection/src/traits/outlives_bounds.rs
@@ -62,9 +62,10 @@ fn implied_outlives_bounds<'a, 'tcx>(
     };
 
     let mut constraints = QueryRegionConstraints::default();
+    let span = infcx.tcx.def_span(body_id);
     let Ok(InferOk { value: mut bounds, obligations }) = infcx
         .instantiate_nll_query_response_and_region_obligations(
-            &ObligationCause::dummy(),
+            &ObligationCause::dummy_with_span(span),
             param_env,
             &canonical_var_values,
             canonical_result,
@@ -80,8 +81,6 @@ fn implied_outlives_bounds<'a, 'tcx>(
     bounds.retain(|bound| !bound.has_placeholders());
 
     if !constraints.is_empty() {
-        let span = infcx.tcx.def_span(body_id);
-
         debug!(?constraints);
         if !constraints.member_constraints.is_empty() {
             span_bug!(span, "{:#?}", constraints.member_constraints);
diff --git a/tests/ui/inference/issue-80409.no-compat.stderr b/tests/ui/inference/issue-80409.no-compat.stderr
@@ -1,6 +1,16 @@
 error: internal compiler error: error performing ParamEnvAnd { param_env: ParamEnv { caller_bounds: [], reveal: UserFacing }, value: ImpliedOutlivesBounds { ty: &'?2 mut StateContext<'?3, usize> } }
+  --> $DIR/issue-80409.rs:48:30
    |
-   = query stack during panic:
+LL |     builder.state().on_entry(|_| {});
+   |                              ^^^
+   |
+note: delayed at /home/gh-estebank/rust/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs:164:29 - disabled backtrace
+  --> $DIR/issue-80409.rs:48:30
+   |
+LL |     builder.state().on_entry(|_| {});
+   |                              ^^^
+
+query stack during panic:
 end of query stack
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/lifetimes/static-impl-obligation.rs b/tests/ui/lifetimes/static-impl-obligation.rs
@@ -0,0 +1,195 @@
+mod a {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo { //~ HELP consider relaxing the implicit `'static` requirement
+        fn hello(&self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod b {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo {
+        fn hello(&'static self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod c {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo {
+        fn hello(&'static self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod d {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo {
+        fn hello(&self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod e {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static { //~ HELP consider replacing this `'static` requirement
+        fn hello(&self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod f {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static {
+        fn hello(&'static self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod g {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static {
+        fn hello(&'static self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod h {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static {
+        fn hello(&self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod i {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo where Self: 'static {
+        fn hello(&self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod j {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo where Self: 'static {
+        fn hello(&'static self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod k {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo where Self: 'static {
+        fn hello(&'static self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod l {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo where Self: 'static {
+        fn hello(&self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod m {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static where Self: 'static {
+        fn hello(&self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod n {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static where Self: 'static {
+        fn hello(&'static self) {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod o {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static where Self: 'static {
+        fn hello(&'static self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod p {
+    trait Foo {}
+    impl<'a> Foo for &'a u32 {}
+    impl dyn Foo + 'static where Self: 'static {
+        fn hello(&self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a u32) {
+        let y: &dyn Foo = x; //~ ERROR lifetime may not live long enough
+        y.hello();
+    }
+}
+mod q {
+    struct Foo {}
+    impl Foo {
+        fn hello(&'static self) {}
+    }
+    fn bar<'a>(x: &'a &'a Foo) {
+        x.hello(); //~ ERROR borrowed data escapes outside of function
+    }
+}
+mod r {
+    struct Foo {}
+    impl Foo {
+        fn hello(&'static self) where Self: 'static {}
+    }
+    fn bar<'a>(x: &'a &'a Foo) {
+        x.hello(); //~ ERROR borrowed data escapes outside of function
+    }
+}
+fn main() {}
diff --git a/tests/ui/lifetimes/static-impl-obligation.stderr b/tests/ui/lifetimes/static-impl-obligation.stderr
diff --git a/tests/ui/regions/issue-78262.base.stderr b/tests/ui/regions/issue-78262.base.stderr
diff --git a/tests/ui/regions/issue-78262.polonius.stderr b/tests/ui/regions/issue-78262.polonius.stderr
diff --git a/tests/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.stderr b/tests/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.stderr

Original file line number	Diff line number	Diff line change
`@@ -2051,6 +2051,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {`
`2051`	`2051`	`CRATE_DEF_ID.to_def_id(),`
`2052`	`2052`	`predicate_span,`
`2053`	`2053`	`))`
	`2054`	`+ } else if let ConstraintCategory::CallArgument(Some(fn_def)) = constraint.category {`
	`2055`	`+ Some(ObligationCauseCode::MethodCallConstraint(fn_def, constraint.span))`
`2054`	`2056`	`} else {`
`2055`	`2057`	`None`
`2056`	`2058`	`}`
Original file line number	Diff line number	Diff line change
`@@ -451,6 +451,9 @@ pub enum ObligationCauseCode<'tcx> {`
`451`	`451`
`452`	`452`	`/// Obligations emitted during the normalization of a weak type alias.`
`453`	`453`	`TypeAlias(InternedObligationCauseCode<'tcx>, Span, DefId),`
	`454`	`+`
	`455`	`+ /// During borrowck we've found a method call that could have introduced a lifetime requirement.`
	`456`	`+ MethodCallConstraint(Ty<'tcx>, Span),`
`454`	`457`	`}`
`455`	`458`
`456`	`459`	`/// Whether a value can be extracted into a const.`