Rollup of 8 pull requests

Cargo.lock

@@ -3451,9 +3451,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.16.0"
+version = "1.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "86f0b0d4bf799edbc74508c1e8bf170ff5f41238e5f8225603ca7caaae2b7860"
+checksum = "b7e5500299e16ebb147ae15a00a942af264cf3688f47923b8fc2cd5858f23ad3"
 
 [[package]]
 name = "opener"
@@ -6101,6 +6101,15 @@ version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6bdef32e8150c2a081110b42772ffe7d7c9032b606bc226c8260fd97e0976601"
 
+[[package]]
+name = "suggest-tests"
+version = "0.1.0"
+dependencies = [
+ "build_helper",
+ "glob",
+ "once_cell",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.102"

Cargo.toml

@@ -44,6 +44,7 @@ members = [
   "src/tools/lld-wrapper",
   "src/tools/collect-license-metadata",
   "src/tools/generate-copyright",
+  "src/tools/suggest-tests",
 ]
 
 exclude = [

compiler/rustc_hir_typeck/src/generator_interior/mod.rs

@@ -239,8 +239,7 @@ pub fn resolve_interior<'a, 'tcx>(
             // typeck had previously found constraints that would cause them to be related.
 
             let mut counter = 0;
-            let mut mk_bound_region = |span| {
-                let kind = ty::BrAnon(span);
+            let mut mk_bound_region = |kind| {
                 let var = ty::BoundVar::from_u32(counter);
                 counter += 1;
                 ty::BoundRegion { var, kind }
@@ -252,24 +251,23 @@ pub fn resolve_interior<'a, 'tcx>(
                         let origin = fcx.region_var_origin(vid);
                         match origin {
                             RegionVariableOrigin::EarlyBoundRegion(span, _) => {
-                                mk_bound_region(Some(span))
+                                mk_bound_region(ty::BrAnon(Some(span)))
                             }
-                            _ => mk_bound_region(None),
+                            _ => mk_bound_region(ty::BrAnon(None)),
                         }
                     }
-                    // FIXME: these should use `BrNamed`
                     ty::ReEarlyBound(region) => {
-                        mk_bound_region(Some(fcx.tcx.def_span(region.def_id)))
+                        mk_bound_region(ty::BrNamed(region.def_id, region.name))
                     }
                     ty::ReLateBound(_, ty::BoundRegion { kind, .. })
                     | ty::ReFree(ty::FreeRegion { bound_region: kind, .. }) => match kind {
-                        ty::BoundRegionKind::BrAnon(span) => mk_bound_region(span),
-                        ty::BoundRegionKind::BrNamed(def_id, _) => {
-                            mk_bound_region(Some(fcx.tcx.def_span(def_id)))
+                        ty::BoundRegionKind::BrAnon(span) => mk_bound_region(ty::BrAnon(span)),
+                        ty::BoundRegionKind::BrNamed(def_id, sym) => {
+                            mk_bound_region(ty::BrNamed(def_id, sym))
                         }
-                        ty::BoundRegionKind::BrEnv => mk_bound_region(None),
+                        ty::BoundRegionKind::BrEnv => mk_bound_region(ty::BrAnon(None)),
                     },
-                    _ => mk_bound_region(None),
+                    _ => mk_bound_region(ty::BrAnon(None)),
                 };
                 let r = fcx.tcx.mk_re_late_bound(current_depth, br);
                 r
@@ -293,10 +291,7 @@ pub fn resolve_interior<'a, 'tcx>(
             type_causes,
             FnMutDelegate {
                 regions: &mut |br| {
-                    let kind = match br.kind {
-                        ty::BrAnon(span) => ty::BrAnon(span),
-                        _ => br.kind,
-                    };
+                    let kind = br.kind;
                     let var = ty::BoundVar::from_usize(bound_vars.len());
                     bound_vars.push(ty::BoundVariableKind::Region(kind));
                     counter += 1;

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1927,6 +1927,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         {
             let span = self.tcx.def_span(def_id);
             diag.span_note(span, "this closure does not fulfill the lifetime requirements");
+            self.suggest_for_all_lifetime_closure(span, self.tcx.hir().get_by_def_id(def_id), &exp_found, diag);
         }
 
         // It reads better to have the error origin as the final

compiler/rustc_infer/src/infer/error_reporting/suggest.rs

@@ -8,7 +8,7 @@ use rustc_middle::traits::{
     StatementAsExpression,
 };
 use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::{self as ty, IsSuggestable, Ty, TypeVisitableExt};
+use rustc_middle::ty::{self as ty, GenericArgKind, IsSuggestable, Ty, TypeVisitableExt};
 use rustc_span::{sym, BytePos, Span};
 use rustc_target::abi::FieldIdx;
 
@@ -536,6 +536,82 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
         None
     }
+
+    /// For "one type is more general than the other" errors on closures, suggest changing the lifetime
+    /// of the parameters to accept all lifetimes.
+    pub(super) fn suggest_for_all_lifetime_closure(
+        &self,
+        span: Span,
+        hir: hir::Node<'_>,
+        exp_found: &ty::error::ExpectedFound<ty::PolyTraitRef<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        // 0. Extract fn_decl from hir
+        let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(hir::Closure { body, fn_decl, .. }), .. }) = hir else { return; };
+        let hir::Body { params, .. } = self.tcx.hir().body(*body);
+
+        // 1. Get the substs of the closure.
+        // 2. Assume exp_found is FnOnce / FnMut / Fn, we can extract function parameters from [1].
+        let Some(expected) = exp_found.expected.skip_binder().substs.get(1) else { return; };
+        let Some(found) = exp_found.found.skip_binder().substs.get(1) else { return; };
+        let expected = expected.unpack();
+        let found = found.unpack();
+        // 3. Extract the tuple type from Fn trait and suggest the change.
+        if let GenericArgKind::Type(expected) = expected &&
+            let GenericArgKind::Type(found) = found &&
+            let ty::Tuple(expected) = expected.kind() &&
+            let ty::Tuple(found)= found.kind() &&
+            expected.len() == found.len() {
+            let mut suggestion = "|".to_string();
+            let mut is_first = true;
+            let mut has_suggestion = false;
+
+            for (((expected, found), param_hir), arg_hir) in expected.iter()
+                .zip(found.iter())
+                .zip(params.iter())
+                .zip(fn_decl.inputs.iter()) {
+                if is_first {
+                    is_first = false;
+                } else {
+                    suggestion += ", ";
+                }
+
+                if let ty::Ref(expected_region, _, _) = expected.kind() &&
+                    let ty::Ref(found_region, _, _) = found.kind() &&
+                    expected_region.is_late_bound() &&
+                    !found_region.is_late_bound() &&
+                    let hir::TyKind::Infer = arg_hir.kind {
+                    // If the expected region is late bound, the found region is not, and users are asking compiler
+                    // to infer the type, we can suggest adding `: &_`.
+                    if param_hir.pat.span == param_hir.ty_span {
+                        // for `|x|`, `|_|`, `|x: impl Foo|`
+                        let Ok(pat) = self.tcx.sess.source_map().span_to_snippet(param_hir.pat.span) else { return; };
+                        suggestion += &format!("{}: &_", pat);
+                    } else {
+                        // for `|x: ty|`, `|_: ty|`
+                        let Ok(pat) = self.tcx.sess.source_map().span_to_snippet(param_hir.pat.span) else { return; };
+                        let Ok(ty) = self.tcx.sess.source_map().span_to_snippet(param_hir.ty_span) else { return; };
+                        suggestion += &format!("{}: &{}", pat, ty);
+                    }
+                    has_suggestion = true;
+                } else {
+                    let Ok(arg) = self.tcx.sess.source_map().span_to_snippet(param_hir.span) else { return; };
+                    // Otherwise, keep it as-is.
+                    suggestion += &arg;
+                }
+            }
+            suggestion += "|";
+
+            if has_suggestion {
+                diag.span_suggestion_verbose(
+                    span,
+                    "consider specifying the type of the closure parameters",
+                    suggestion,
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        }
+    }
 }
 
 impl<'tcx> TypeErrCtxt<'_, 'tcx> {

compiler/rustc_middle/src/hir/mod.rs

@@ -7,7 +7,7 @@ pub mod nested_filter;
 pub mod place;
 
 use crate::ty::query::Providers;
-use crate::ty::{ImplSubject, TyCtxt};
+use crate::ty::{EarlyBinder, ImplSubject, TyCtxt};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{par_for_each_in, Send, Sync};
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -104,11 +104,11 @@ impl<'tcx> TyCtxt<'tcx> {
         self.parent_module_from_def_id(id.owner.def_id)
     }
 
-    pub fn impl_subject(self, def_id: DefId) -> ImplSubject<'tcx> {
-        self.impl_trait_ref(def_id)
-            .map(|t| t.subst_identity())
-            .map(ImplSubject::Trait)
-            .unwrap_or_else(|| ImplSubject::Inherent(self.type_of(def_id).subst_identity()))
+    pub fn impl_subject(self, def_id: DefId) -> EarlyBinder<ImplSubject<'tcx>> {
+        match self.impl_trait_ref(def_id) {
+            Some(t) => t.map_bound(ImplSubject::Trait),
+            None => self.type_of(def_id).map_bound(ImplSubject::Inherent),
+        }
     }
 }
 

compiler/rustc_middle/src/ty/util.rs

@@ -708,10 +708,6 @@ impl<'tcx> TyCtxt<'tcx> {
         ty::EarlyBinder(self.explicit_item_bounds(def_id))
     }
 
-    pub fn bound_impl_subject(self, def_id: DefId) -> ty::EarlyBinder<ty::ImplSubject<'tcx>> {
-        ty::EarlyBinder(self.impl_subject(def_id))
-    }
-
     /// Returns names of captured upvars for closures and generators.
     ///
     /// Here are some examples:

compiler/rustc_trait_selection/src/solve/canonicalize.rs

@@ -125,8 +125,9 @@ impl<'a, 'tcx> Canonicalizer<'a, 'tcx> {
         // - var_infos: [E0, U1, E1, U1, E1, E6, U6], curr_compressed_uv: 1, next_orig_uv: 6
         // - var_infos: [E0, U1, E1, U1, E1, E2, U2], curr_compressed_uv: 2, next_orig_uv: -
         //
-        // This algorithm runs in `O(n²)` where `n` is the number of different universe
-        // indices in the input. This should be fine as `n` is expected to be small.
+        // This algorithm runs in `O(nm)` where `n` is the number of different universe
+        // indices in the input and `m` is the number of canonical variables.
+        // This should be fine as both `n` and `m` are expected to be small.
         let mut curr_compressed_uv = ty::UniverseIndex::ROOT;
         let mut existential_in_new_uv = false;
         let mut next_orig_uv = Some(ty::UniverseIndex::ROOT);
@@ -245,18 +246,14 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'_, 'tcx> {
             ty::ReError(_) => return r,
         };
 
-        let existing_bound_var = match self.canonicalize_mode {
-            CanonicalizeMode::Input => None,
-            CanonicalizeMode::Response { .. } => {
-                self.variables.iter().position(|&v| v == r.into()).map(ty::BoundVar::from)
-            }
-        };
-        let var = existing_bound_var.unwrap_or_else(|| {
-            let var = ty::BoundVar::from(self.variables.len());
-            self.variables.push(r.into());
-            self.primitive_var_infos.push(CanonicalVarInfo { kind });
-            var
-        });
+        let var = ty::BoundVar::from(
+            self.variables.iter().position(|&v| v == r.into()).unwrap_or_else(|| {
+                let var = self.variables.len();
+                self.variables.push(r.into());
+                self.primitive_var_infos.push(CanonicalVarInfo { kind });
+                var
+            }),
+        );
         let br = ty::BoundRegion { var, kind: BrAnon(None) };
         self.interner().mk_re_late_bound(self.binder_index, br)
     }

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -306,7 +306,7 @@ fn negative_impl(tcx: TyCtxt<'_>, impl1_def_id: DefId, impl2_def_id: DefId) -> b
         &infcx,
         ObligationCause::dummy(),
         impl_env,
-        tcx.impl_subject(impl1_def_id),
+        tcx.impl_subject(impl1_def_id).subst_identity(),
     ) {
         Ok(s) => s,
         Err(err) => {

compiler/rustc_trait_selection/src/traits/util.rs

@@ -198,7 +198,7 @@ pub fn impl_subject_and_oblig<'a, 'tcx>(
     impl_def_id: DefId,
     impl_substs: SubstsRef<'tcx>,
 ) -> (ImplSubject<'tcx>, impl Iterator<Item = PredicateObligation<'tcx>>) {
-    let subject = selcx.tcx().bound_impl_subject(impl_def_id);
+    let subject = selcx.tcx().impl_subject(impl_def_id);
     let subject = subject.subst(selcx.tcx(), impl_substs);
 
     let InferOk { value: subject, obligations: normalization_obligations1 } =