Auto merge of #123982 - compiler-errors:rollup-m2v4epp, r=compiler-er…

…rors

Rollup of 4 pull requests

Successful merges:

 - #123900 (Stop using `PolyTraitRef` for closure/coroutine predicates already instantiated w placeholders)
 - #123924 (Fix various bugs in `ty_kind_suggestion`)
 - #123943 (Use the rustc_private libc less in tests)
 - #123970 (zkvm: fix references to `os_str` module)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -671,68 +671,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         err
     }
 
-    fn ty_kind_suggestion(&self, ty: Ty<'tcx>) -> Option<String> {
-        // Keep in sync with `rustc_hir_analysis/src/check/mod.rs:ty_kind_suggestion`.
-        // FIXME: deduplicate the above.
-        let tcx = self.infcx.tcx;
-        let implements_default = |ty| {
-            let Some(default_trait) = tcx.get_diagnostic_item(sym::Default) else {
-                return false;
-            };
-            self.infcx
-                .type_implements_trait(default_trait, [ty], self.param_env)
-                .must_apply_modulo_regions()
-        };
-
-        Some(match ty.kind() {
-            ty::Never | ty::Error(_) => return None,
-            ty::Bool => "false".to_string(),
-            ty::Char => "\'x\'".to_string(),
-            ty::Int(_) | ty::Uint(_) => "42".into(),
-            ty::Float(_) => "3.14159".into(),
-            ty::Slice(_) => "[]".to_string(),
-            ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::Vec) => {
-                "vec![]".to_string()
-            }
-            ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::String) => {
-                "String::new()".to_string()
-            }
-            ty::Adt(def, args) if def.is_box() => {
-                format!("Box::new({})", self.ty_kind_suggestion(args[0].expect_ty())?)
-            }
-            ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::Option) => {
-                "None".to_string()
-            }
-            ty::Adt(def, args) if Some(def.did()) == tcx.get_diagnostic_item(sym::Result) => {
-                format!("Ok({})", self.ty_kind_suggestion(args[0].expect_ty())?)
-            }
-            ty::Adt(_, _) if implements_default(ty) => "Default::default()".to_string(),
-            ty::Ref(_, ty, mutability) => {
-                if let (ty::Str, hir::Mutability::Not) = (ty.kind(), mutability) {
-                    "\"\"".to_string()
-                } else {
-                    let Some(ty) = self.ty_kind_suggestion(*ty) else {
-                        return None;
-                    };
-                    format!("&{}{ty}", mutability.prefix_str())
-                }
-            }
-            ty::Array(ty, len) => format!(
-                "[{}; {}]",
-                self.ty_kind_suggestion(*ty)?,
-                len.eval_target_usize(tcx, ty::ParamEnv::reveal_all()),
-            ),
-            ty::Tuple(tys) => format!(
-                "({})",
-                tys.iter()
-                    .map(|ty| self.ty_kind_suggestion(ty))
-                    .collect::<Option<Vec<String>>>()?
-                    .join(", ")
-            ),
-            _ => "value".to_string(),
-        })
-    }
-
     fn suggest_assign_value(
         &self,
         err: &mut Diag<'_>,
@@ -742,7 +680,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let ty = moved_place.ty(self.body, self.infcx.tcx).ty;
         debug!("ty: {:?}, kind: {:?}", ty, ty.kind());
 
-        let Some(assign_value) = self.ty_kind_suggestion(ty) else {
+        let Some(assign_value) = self.infcx.err_ctxt().ty_kind_suggestion(self.param_env, ty)
+        else {
             return;
         };
 

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -81,7 +81,6 @@ use rustc_errors::ErrorGuaranteed;
 use rustc_errors::{pluralize, struct_span_code_err, Diag};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::Visitor;
-use rustc_hir::Mutability;
 use rustc_index::bit_set::BitSet;
 use rustc_infer::infer::error_reporting::ObligationCauseExt as _;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
@@ -96,8 +95,9 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{def_id::CRATE_DEF_ID, BytePos, Span, Symbol, DUMMY_SP};
 use rustc_target::abi::VariantIdx;
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor;
+use rustc_trait_selection::traits::error_reporting::suggestions::{
+    ReturnsVisitor, TypeErrCtxtExt as _,
+};
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::ObligationCtxt;
 
@@ -467,67 +467,6 @@ fn fn_sig_suggestion<'tcx>(
     )
 }
 
-pub fn ty_kind_suggestion<'tcx>(ty: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<String> {
-    // Keep in sync with `rustc_borrowck/src/diagnostics/conflict_errors.rs:ty_kind_suggestion`.
-    // FIXME: deduplicate the above.
-    let implements_default = |ty| {
-        let Some(default_trait) = tcx.get_diagnostic_item(sym::Default) else {
-            return false;
-        };
-        let infcx = tcx.infer_ctxt().build();
-        infcx
-            .type_implements_trait(default_trait, [ty], ty::ParamEnv::reveal_all())
-            .must_apply_modulo_regions()
-    };
-    Some(match ty.kind() {
-        ty::Never | ty::Error(_) => return None,
-        ty::Bool => "false".to_string(),
-        ty::Char => "\'x\'".to_string(),
-        ty::Int(_) | ty::Uint(_) => "42".into(),
-        ty::Float(_) => "3.14159".into(),
-        ty::Slice(_) => "[]".to_string(),
-        ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::Vec) => {
-            "vec![]".to_string()
-        }
-        ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::String) => {
-            "String::new()".to_string()
-        }
-        ty::Adt(def, args) if def.is_box() => {
-            format!("Box::new({})", ty_kind_suggestion(args[0].expect_ty(), tcx)?)
-        }
-        ty::Adt(def, _) if Some(def.did()) == tcx.get_diagnostic_item(sym::Option) => {
-            "None".to_string()
-        }
-        ty::Adt(def, args) if Some(def.did()) == tcx.get_diagnostic_item(sym::Result) => {
-            format!("Ok({})", ty_kind_suggestion(args[0].expect_ty(), tcx)?)
-        }
-        ty::Adt(_, _) if implements_default(ty) => "Default::default()".to_string(),
-        ty::Ref(_, ty, mutability) => {
-            if let (ty::Str, Mutability::Not) = (ty.kind(), mutability) {
-                "\"\"".to_string()
-            } else {
-                let Some(ty) = ty_kind_suggestion(*ty, tcx) else {
-                    return None;
-                };
-                format!("&{}{ty}", mutability.prefix_str())
-            }
-        }
-        ty::Array(ty, len) => format!(
-            "[{}; {}]",
-            ty_kind_suggestion(*ty, tcx)?,
-            len.eval_target_usize(tcx, ty::ParamEnv::reveal_all()),
-        ),
-        ty::Tuple(tys) => format!(
-            "({})",
-            tys.iter()
-                .map(|ty| ty_kind_suggestion(ty, tcx))
-                .collect::<Option<Vec<String>>>()?
-                .join(", ")
-        ),
-        _ => "value".to_string(),
-    })
-}
-
 /// Return placeholder code for the given associated item.
 /// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a
 /// structured suggestion.
@@ -562,7 +501,12 @@ fn suggestion_signature<'tcx>(
         }
         ty::AssocKind::Const => {
             let ty = tcx.type_of(assoc.def_id).instantiate_identity();
-            let val = ty_kind_suggestion(ty, tcx).unwrap_or_else(|| "value".to_string());
+            let val = tcx
+                .infer_ctxt()
+                .build()
+                .err_ctxt()
+                .ty_kind_suggestion(tcx.param_env(assoc.def_id), ty)
+                .unwrap_or_else(|| "value".to_string());
             format!("const {}: {} = {};", assoc.name, ty, val)
         }
     }

compiler/rustc_hir_typeck/src/coercion.rs

@@ -63,6 +63,7 @@ use rustc_span::DesugaringKind;
 use rustc_span::{BytePos, Span};
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::TraitEngineExt as _;
@@ -1616,6 +1617,15 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                             E0069,
                             "`return;` in a function whose return type is not `()`"
                         );
+                        if let Some(value) = fcx.err_ctxt().ty_kind_suggestion(fcx.param_env, found)
+                        {
+                            err.span_suggestion_verbose(
+                                cause.span.shrink_to_hi(),
+                                "give the `return` a value of the expected type",
+                                format!(" {value}"),
+                                Applicability::HasPlaceholders,
+                            );
+                        }
                         err.span_label(cause.span, "return type is not `()`");
                     }
                     ObligationCauseCode::BlockTailExpression(blk_id, ..) => {

compiler/rustc_hir_typeck/src/expr.rs

@@ -35,7 +35,6 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{ExprKind, HirId, QPath};
-use rustc_hir_analysis::check::ty_kind_suggestion;
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer as _;
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
@@ -57,6 +56,7 @@ use rustc_span::Span;
 use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 use rustc_target::spec::abi::Abi::RustIntrinsic;
 use rustc_trait_selection::infer::InferCtxtExt;
+use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_trait_selection::traits::{self, ObligationCauseCode};
@@ -694,7 +694,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             );
                             let error = Some(Sorts(ExpectedFound { expected: ty, found: e_ty }));
                             self.annotate_loop_expected_due_to_inference(err, expr, error);
-                            if let Some(val) = ty_kind_suggestion(ty, tcx) {
+                            if let Some(val) =
+                                self.err_ctxt().ty_kind_suggestion(self.param_env, ty)
+                            {
                                 err.span_suggestion_verbose(
                                     expr.span.shrink_to_hi(),
                                     "give the `break` a value of the expected type",

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -367,7 +367,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }),
         ) = error.code
             && let ty::Closure(def_id, _) | ty::Coroutine(def_id, ..) =
-                expected_trait_ref.skip_binder().self_ty().kind()
+                expected_trait_ref.self_ty().kind()
             && span.overlaps(self.tcx.def_span(*def_id))
         {
             true

compiler/rustc_infer/src/infer/at.rs

@@ -424,25 +424,7 @@ impl<'tcx> ToTrace<'tcx> for ty::TraitRef<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(
-                a_is_expected,
-                ty::Binder::dummy(a),
-                ty::Binder::dummy(b),
-            )),
-        }
-    }
-}
-
-impl<'tcx> ToTrace<'tcx> for ty::PolyTraitRef<'tcx> {
-    fn to_trace(
-        cause: &ObligationCause<'tcx>,
-        a_is_expected: bool,
-        a: Self,
-        b: Self,
-    ) -> TypeTrace<'tcx> {
-        TypeTrace {
-            cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }

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

@@ -1653,7 +1653,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             .report(diag);
                         (false, Mismatch::Fixed("signature"))
                     }
-                    ValuePairs::PolyTraitRefs(_) => (false, Mismatch::Fixed("trait")),
+                    ValuePairs::TraitRefs(_) => (false, Mismatch::Fixed("trait")),
                     ValuePairs::Aliases(infer::ExpectedFound { expected, .. }) => {
                         (false, Mismatch::Fixed(self.tcx.def_descr(expected.def_id)))
                     }
@@ -1969,8 +1969,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             self.note_and_explain_type_err(diag, exp_found, cause, span, cause.body_id.to_def_id());
         }
 
-        if let Some(ValuePairs::PolyTraitRefs(exp_found)) = values
-            && let ty::Closure(def_id, _) = exp_found.expected.skip_binder().self_ty().kind()
+        if let Some(ValuePairs::TraitRefs(exp_found)) = values
+            && let ty::Closure(def_id, _) = exp_found.expected.self_ty().kind()
             && let Some(def_id) = def_id.as_local()
             && terr.involves_regions()
         {
@@ -2188,7 +2188,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Aliases(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
-            infer::PolyTraitRefs(exp_found) => {
+            infer::TraitRefs(exp_found) => {
                 let pretty_exp_found = ty::error::ExpectedFound {
                     expected: exp_found.expected.print_trait_sugared(),
                     found: exp_found.found.print_trait_sugared(),

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs

@@ -195,13 +195,13 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         value_pairs: &ValuePairs<'tcx>,
     ) -> Option<Diag<'tcx>> {
         let (expected_args, found_args, trait_def_id) = match value_pairs {
-            ValuePairs::PolyTraitRefs(ExpectedFound { expected, found })
-                if expected.def_id() == found.def_id() =>
+            ValuePairs::TraitRefs(ExpectedFound { expected, found })
+                if expected.def_id == found.def_id =>
             {
                 // It's possible that the placeholders come from a binder
                 // outside of this value pair. Use `no_bound_vars` as a
                 // simple heuristic for that.
-                (expected.no_bound_vars()?.args, found.no_bound_vars()?.args, expected.def_id())
+                (expected.args, found.args, expected.def_id)
             }
             _ => return None,
         };

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

@@ -599,7 +599,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         span: Span,
         hir: hir::Node<'_>,
-        exp_found: &ty::error::ExpectedFound<ty::PolyTraitRef<'tcx>>,
+        exp_found: &ty::error::ExpectedFound<ty::TraitRef<'tcx>>,
         diag: &mut Diag<'_>,
     ) {
         // 0. Extract fn_decl from hir
@@ -614,10 +614,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         // 1. Get the args 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().args.get(1) else {
+        let Some(expected) = exp_found.expected.args.get(1) else {
             return;
         };
-        let Some(found) = exp_found.found.skip_binder().args.get(1) else {
+        let Some(found) = exp_found.found.args.get(1) else {
             return;
         };
         let expected = expected.unpack();

compiler/rustc_infer/src/infer/mod.rs

@@ -403,7 +403,7 @@ pub enum ValuePairs<'tcx> {
     Regions(ExpectedFound<ty::Region<'tcx>>),
     Terms(ExpectedFound<ty::Term<'tcx>>),
     Aliases(ExpectedFound<ty::AliasTy<'tcx>>),
-    PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
+    TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
     PolySigs(ExpectedFound<ty::PolyFnSig<'tcx>>),
     ExistentialTraitRef(ExpectedFound<ty::PolyExistentialTraitRef<'tcx>>),
     ExistentialProjection(ExpectedFound<ty::PolyExistentialProjection<'tcx>>),
@@ -1882,15 +1882,15 @@ impl<'tcx> TypeTrace<'tcx> {
         }
     }
 
-    pub fn poly_trait_refs(
+    pub fn trait_refs(
         cause: &ObligationCause<'tcx>,
         a_is_expected: bool,
-        a: ty::PolyTraitRef<'tcx>,
-        b: ty::PolyTraitRef<'tcx>,
+        a: ty::TraitRef<'tcx>,
+        b: ty::TraitRef<'tcx>,
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 

compiler/rustc_middle/src/traits/mod.rs

@@ -620,11 +620,10 @@ pub enum SelectionError<'tcx> {
     OpaqueTypeAutoTraitLeakageUnknown(DefId),
 }
 
-// FIXME(@lcnr): The `Binder` here should be unnecessary. Just use `TraitRef` instead.
 #[derive(Clone, Debug, TypeVisitable)]
 pub struct SignatureMismatchData<'tcx> {
-    pub found_trait_ref: ty::PolyTraitRef<'tcx>,
-    pub expected_trait_ref: ty::PolyTraitRef<'tcx>,
+    pub found_trait_ref: ty::TraitRef<'tcx>,
+    pub expected_trait_ref: ty::TraitRef<'tcx>,
     pub terr: ty::error::TypeError<'tcx>,
 }
 

compiler/rustc_trait_selection/src/lib.rs

@@ -22,6 +22,7 @@
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]
 #![feature(extract_if)]
+#![feature(if_let_guard)]
 #![feature(let_chains)]
 #![feature(option_take_if)]
 #![feature(never_type)]