Rollup of 8 pull requests

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1432,7 +1432,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         return;
                     }
                 };
-                let (sig, map) = tcx.instantiate_bound_regions(sig, |br| {
+                let (unnormalized_sig, map) = tcx.instantiate_bound_regions(sig, |br| {
                     use crate::renumber::RegionCtxt;
 
                     let region_ctxt_fn = || {
@@ -1454,7 +1454,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         region_ctxt_fn,
                     )
                 });
-                debug!(?sig);
+                debug!(?unnormalized_sig);
                 // IMPORTANT: We have to prove well formed for the function signature before
                 // we normalize it, as otherwise types like `<&'a &'b () as Trait>::Assoc`
                 // get normalized away, causing us to ignore the `'b: 'a` bound used by the function.
@@ -1464,15 +1464,31 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 //
                 // See #91068 for an example.
                 self.prove_predicates(
-                    sig.inputs_and_output.iter().map(|ty| {
+                    unnormalized_sig.inputs_and_output.iter().map(|ty| {
                         ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::WellFormed(
                             ty.into(),
                         )))
                     }),
                     term_location.to_locations(),
                     ConstraintCategory::Boring,
                 );
-                let sig = self.normalize(sig, term_location);
+
+                let sig = self.normalize(unnormalized_sig, term_location);
+                // HACK(#114936): `WF(sig)` does not imply `WF(normalized(sig))`
+                // with built-in `Fn` implementations, since the impl may not be
+                // well-formed itself.
+                if sig != unnormalized_sig {
+                    self.prove_predicates(
+                        sig.inputs_and_output.iter().map(|ty| {
+                            ty::Binder::dummy(ty::PredicateKind::Clause(
+                                ty::ClauseKind::WellFormed(ty.into()),
+                            ))
+                        }),
+                        term_location.to_locations(),
+                        ConstraintCategory::Boring,
+                    );
+                }
+
                 self.check_call_dest(body, term, &sig, *destination, *target, term_location);
 
                 // The ordinary liveness rules will ensure that all

compiler/rustc_infer/src/infer/at.rs

@@ -285,13 +285,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         T: Relate<'tcx>,
     {
         let Trace { at, trace, a_is_expected } = self;
-        at.infcx.commit_if_ok(|_| {
-            let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
-            fields
-                .sub(a_is_expected)
-                .relate(a, b)
-                .map(move |_| InferOk { value: (), obligations: fields.obligations })
-        })
+        let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
+        fields
+            .sub(a_is_expected)
+            .relate(a, b)
+            .map(move |_| InferOk { value: (), obligations: fields.obligations })
     }
 
     /// Makes `a == b`; the expectation is set by the call to
@@ -302,13 +300,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         T: Relate<'tcx>,
     {
         let Trace { at, trace, a_is_expected } = self;
-        at.infcx.commit_if_ok(|_| {
-            let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
-            fields
-                .equate(a_is_expected)
-                .relate(a, b)
-                .map(move |_| InferOk { value: (), obligations: fields.obligations })
-        })
+        let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
+        fields
+            .equate(a_is_expected)
+            .relate(a, b)
+            .map(move |_| InferOk { value: (), obligations: fields.obligations })
     }
 
     #[instrument(skip(self), level = "debug")]
@@ -317,13 +313,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         T: Relate<'tcx>,
     {
         let Trace { at, trace, a_is_expected } = self;
-        at.infcx.commit_if_ok(|_| {
-            let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
-            fields
-                .lub(a_is_expected)
-                .relate(a, b)
-                .map(move |t| InferOk { value: t, obligations: fields.obligations })
-        })
+        let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
+        fields
+            .lub(a_is_expected)
+            .relate(a, b)
+            .map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 
     #[instrument(skip(self), level = "debug")]
@@ -332,13 +326,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         T: Relate<'tcx>,
     {
         let Trace { at, trace, a_is_expected } = self;
-        at.infcx.commit_if_ok(|_| {
-            let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
-            fields
-                .glb(a_is_expected)
-                .relate(a, b)
-                .map(move |t| InferOk { value: t, obligations: fields.obligations })
-        })
+        let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
+        fields
+            .glb(a_is_expected)
+            .relate(a, b)
+            .map(move |t| InferOk { value: t, obligations: fields.obligations })
     }
 }
 

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -620,42 +620,40 @@ impl<'tcx> InferCtxt<'tcx> {
         variables1: &OriginalQueryValues<'tcx>,
         variables2: impl Fn(BoundVar) -> GenericArg<'tcx>,
     ) -> InferResult<'tcx, ()> {
-        self.commit_if_ok(|_| {
-            let mut obligations = vec![];
-            for (index, value1) in variables1.var_values.iter().enumerate() {
-                let value2 = variables2(BoundVar::new(index));
-
-                match (value1.unpack(), value2.unpack()) {
-                    (GenericArgKind::Type(v1), GenericArgKind::Type(v2)) => {
-                        obligations.extend(
-                            self.at(cause, param_env)
-                                .eq(DefineOpaqueTypes::Yes, v1, v2)?
-                                .into_obligations(),
-                        );
-                    }
-                    (GenericArgKind::Lifetime(re1), GenericArgKind::Lifetime(re2))
-                        if re1.is_erased() && re2.is_erased() =>
-                    {
-                        // no action needed
-                    }
-                    (GenericArgKind::Lifetime(v1), GenericArgKind::Lifetime(v2)) => {
-                        obligations.extend(
-                            self.at(cause, param_env)
-                                .eq(DefineOpaqueTypes::Yes, v1, v2)?
-                                .into_obligations(),
-                        );
-                    }
-                    (GenericArgKind::Const(v1), GenericArgKind::Const(v2)) => {
-                        let ok = self.at(cause, param_env).eq(DefineOpaqueTypes::Yes, v1, v2)?;
-                        obligations.extend(ok.into_obligations());
-                    }
-                    _ => {
-                        bug!("kind mismatch, cannot unify {:?} and {:?}", value1, value2,);
-                    }
+        let mut obligations = vec![];
+        for (index, value1) in variables1.var_values.iter().enumerate() {
+            let value2 = variables2(BoundVar::new(index));
+
+            match (value1.unpack(), value2.unpack()) {
+                (GenericArgKind::Type(v1), GenericArgKind::Type(v2)) => {
+                    obligations.extend(
+                        self.at(cause, param_env)
+                            .eq(DefineOpaqueTypes::Yes, v1, v2)?
+                            .into_obligations(),
+                    );
+                }
+                (GenericArgKind::Lifetime(re1), GenericArgKind::Lifetime(re2))
+                    if re1.is_erased() && re2.is_erased() =>
+                {
+                    // no action needed
+                }
+                (GenericArgKind::Lifetime(v1), GenericArgKind::Lifetime(v2)) => {
+                    obligations.extend(
+                        self.at(cause, param_env)
+                            .eq(DefineOpaqueTypes::Yes, v1, v2)?
+                            .into_obligations(),
+                    );
+                }
+                (GenericArgKind::Const(v1), GenericArgKind::Const(v2)) => {
+                    let ok = self.at(cause, param_env).eq(DefineOpaqueTypes::Yes, v1, v2)?;
+                    obligations.extend(ok.into_obligations());
+                }
+                _ => {
+                    bug!("kind mismatch, cannot unify {:?} and {:?}", value1, value2,);
                 }
             }
-            Ok(InferOk { value: (), obligations })
-        })
+        }
+        Ok(InferOk { value: (), obligations })
     }
 }
 

compiler/rustc_trait_selection/src/solve/assembly/mod.rs

@@ -337,6 +337,13 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         let mut consider_impls_for_simplified_type = |simp| {
             if let Some(impls_for_type) = trait_impls.non_blanket_impls().get(&simp) {
                 for &impl_def_id in impls_for_type {
+                    // For every `default impl`, there's always a non-default `impl`
+                    // that will *also* apply. There's no reason to register a candidate
+                    // for this impl, since it is *not* proof that the trait goal holds.
+                    if tcx.defaultness(impl_def_id).is_default() {
+                        return;
+                    }
+
                     match G::consider_impl_candidate(self, goal, impl_def_id) {
                         Ok(candidate) => candidates.push(candidate),
                         Err(NoSolution) => (),
@@ -440,6 +447,13 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         let tcx = self.tcx();
         let trait_impls = tcx.trait_impls_of(goal.predicate.trait_def_id(tcx));
         for &impl_def_id in trait_impls.blanket_impls() {
+            // For every `default impl`, there's always a non-default `impl`
+            // that will *also* apply. There's no reason to register a candidate
+            // for this impl, since it is *not* proof that the trait goal holds.
+            if tcx.defaultness(impl_def_id).is_default() {
+                return;
+            }
+
             match G::consider_impl_candidate(self, goal, impl_def_id) {
                 Ok(candidate) => candidates.push(candidate),
                 Err(NoSolution) => (),

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -566,6 +566,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 {
                     return;
                 }
+
+                // For every `default impl`, there's always a non-default `impl`
+                // that will *also* apply. There's no reason to register a candidate
+                // for this impl, since it is *not* proof that the trait goal holds.
+                if self.tcx().defaultness(impl_def_id).is_default() {
+                    return;
+                }
+
                 if self.reject_fn_ptr_impls(
                     impl_def_id,
                     obligation,

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -192,13 +192,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             &mut obligations,
         );
 
-        obligations.extend(self.infcx.commit_if_ok(|_| {
+        obligations.extend(
             self.infcx
                 .at(&obligation.cause, obligation.param_env)
                 .sup(DefineOpaqueTypes::No, placeholder_trait_predicate, candidate)
                 .map(|InferOk { obligations, .. }| obligations)
-                .map_err(|_| Unimplemented)
-        })?);
+                .map_err(|_| Unimplemented)?,
+        );
 
         // FIXME(compiler-errors): I don't think this is needed.
         if let ty::Alias(ty::Projection, alias_ty) = placeholder_self_ty.kind() {
@@ -532,13 +532,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             &mut nested,
         );
 
-        nested.extend(self.infcx.commit_if_ok(|_| {
+        nested.extend(
             self.infcx
                 .at(&obligation.cause, obligation.param_env)
                 .sup(DefineOpaqueTypes::No, obligation_trait_ref, upcast_trait_ref)
                 .map(|InferOk { obligations, .. }| obligations)
-                .map_err(|_| Unimplemented)
-        })?);
+                .map_err(|_| Unimplemented)?,
+        );
 
         // Check supertraits hold. This is so that their associated type bounds
         // will be checked in the code below.

library/std/src/process.rs

@@ -171,7 +171,7 @@ pub struct Child {
     /// The handle for writing to the child's standard input (stdin), if it
     /// has been captured. You might find it helpful to do
     ///
-    /// ```compile_fail,E0425
+    /// ```ignore (incomplete)
     /// let stdin = child.stdin.take().unwrap();
     /// ```
     ///
@@ -183,7 +183,7 @@ pub struct Child {
     /// The handle for reading from the child's standard output (stdout), if it
     /// has been captured. You might find it helpful to do
     ///
-    /// ```compile_fail,E0425
+    /// ```ignore (incomplete)
     /// let stdout = child.stdout.take().unwrap();
     /// ```
     ///
@@ -195,7 +195,7 @@ pub struct Child {
     /// The handle for reading from the child's standard error (stderr), if it
     /// has been captured. You might find it helpful to do
     ///
-    /// ```compile_fail,E0425
+    /// ```ignore (incomplete)
     /// let stderr = child.stderr.take().unwrap();
     /// ```
     ///

src/librustdoc/clean/mod.rs

@@ -254,16 +254,14 @@ fn clean_poly_trait_ref_with_bindings<'tcx>(
 }
 
 fn clean_lifetime<'tcx>(lifetime: &hir::Lifetime, cx: &mut DocContext<'tcx>) -> Lifetime {
-    let def = cx.tcx.named_bound_var(lifetime.hir_id);
     if let Some(
-        rbv::ResolvedArg::EarlyBound(node_id)
-        | rbv::ResolvedArg::LateBound(_, _, node_id)
-        | rbv::ResolvedArg::Free(_, node_id),
-    ) = def
+        rbv::ResolvedArg::EarlyBound(did)
+        | rbv::ResolvedArg::LateBound(_, _, did)
+        | rbv::ResolvedArg::Free(_, did),
+    ) = cx.tcx.named_bound_var(lifetime.hir_id)
+        && let Some(lt) = cx.args.get(&did).and_then(|arg| arg.as_lt())
     {
-        if let Some(lt) = cx.args.get(&node_id).and_then(|p| p.as_lt()).cloned() {
-            return lt;
-        }
+        return lt.clone();
     }
     Lifetime(lifetime.ident.name)
 }
@@ -1791,12 +1789,12 @@ fn maybe_expand_private_type_alias<'tcx>(
                     _ => None,
                 });
                 if let Some(lt) = lifetime {
-                    let cleaned = if !lt.is_anonymous() {
+                    let lt = if !lt.is_anonymous() {
                         clean_lifetime(lt, cx)
                     } else {
                         Lifetime::elided()
                     };
-                    args.insert(param.def_id.to_def_id(), InstantiationParam::Lifetime(cleaned));
+                    args.insert(param.def_id.to_def_id(), GenericArg::Lifetime(lt));
                 }
                 indices.lifetimes += 1;
             }
@@ -1805,44 +1803,20 @@ fn maybe_expand_private_type_alias<'tcx>(
                 let type_ = generic_args.args.iter().find_map(|arg| match arg {
                     hir::GenericArg::Type(ty) => {
                         if indices.types == j {
-                            return Some(ty);
+                            return Some(*ty);
                         }
                         j += 1;
                         None
                     }
                     _ => None,
                 });
-                if let Some(ty) = type_ {
-                    args.insert(
-                        param.def_id.to_def_id(),
-                        InstantiationParam::Type(clean_ty(ty, cx)),
-                    );
-                } else if let Some(default) = *default {
-                    args.insert(
-                        param.def_id.to_def_id(),
-                        InstantiationParam::Type(clean_ty(default, cx)),
-                    );
+                if let Some(ty) = type_.or(*default) {
+                    args.insert(param.def_id.to_def_id(), GenericArg::Type(clean_ty(ty, cx)));
                 }
                 indices.types += 1;
             }
-            hir::GenericParamKind::Const { .. } => {
-                let mut j = 0;
-                let const_ = generic_args.args.iter().find_map(|arg| match arg {
-                    hir::GenericArg::Const(ct) => {
-                        if indices.consts == j {
-                            return Some(ct);
-                        }
-                        j += 1;
-                        None
-                    }
-                    _ => None,
-                });
-                if let Some(_) = const_ {
-                    args.insert(param.def_id.to_def_id(), InstantiationParam::Constant);
-                }
-                // FIXME(const_generics_defaults)
-                indices.consts += 1;
-            }
+            // FIXME(#82852): Instantiate const parameters.
+            hir::GenericParamKind::Const { .. } => {}
         }
     }