Rollup merge of rust-lang#134386 - oli-obk:some-trait-impl-diff-diagnostic-cleanups, r=compiler-errors

Some trait method vs impl method signature difference diagnostic cleanups

Just some things I noticed while debugging a weird diagnostic in rust-lang#134353

best reviewed commit by commit

Author: GuillaumeGomez

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -459,11 +459,8 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
     ) -> RegionNameHighlight {
         let mut highlight = RegionHighlightMode::default();
         highlight.highlighting_region_vid(self.infcx.tcx, needle_fr, counter);
-        let type_name = self
-            .infcx
-            .err_ctxt()
-            .extract_inference_diagnostics_data(ty.into(), Some(highlight))
-            .name;
+        let type_name =
+            self.infcx.err_ctxt().extract_inference_diagnostics_data(ty.into(), highlight).name;
 
         debug!(
             "highlight_if_we_cannot_match_hir_ty: type_name={:?} needle_fr={:?}",
@@ -874,7 +871,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
         let type_name = self
             .infcx
             .err_ctxt()
-            .extract_inference_diagnostics_data(yield_ty.into(), Some(highlight))
+            .extract_inference_diagnostics_data(yield_ty.into(), highlight)
             .name;
 
         let yield_span = match tcx.hir_node(self.mir_hir_id()) {

compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs

@@ -21,6 +21,7 @@ use rustc_span::symbol::{Ident, sym};
 use rustc_span::{BytePos, DUMMY_SP, FileName, Span};
 use tracing::{debug, instrument, warn};
 
+use super::nice_region_error::placeholder_error::Highlighted;
 use crate::error_reporting::TypeErrCtxt;
 use crate::errors::{
     AmbiguousImpl, AmbiguousReturn, AnnotationRequired, InferenceBadError,
@@ -279,8 +280,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     pub fn extract_inference_diagnostics_data(
         &self,
         arg: GenericArg<'tcx>,
-        highlight: Option<ty::print::RegionHighlightMode<'tcx>>,
+        highlight: ty::print::RegionHighlightMode<'tcx>,
     ) -> InferenceDiagnosticsData {
+        let tcx = self.tcx;
         match arg.unpack() {
             GenericArgKind::Type(ty) => {
                 if let ty::Infer(ty::TyVar(ty_vid)) = *ty.kind() {
@@ -300,13 +302,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     }
                 }
 
-                let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::TypeNS);
-                if let Some(highlight) = highlight {
-                    printer.region_highlight_mode = highlight;
-                }
-                ty.print(&mut printer).unwrap();
                 InferenceDiagnosticsData {
-                    name: printer.into_buffer(),
+                    name: Highlighted { highlight, ns: Namespace::TypeNS, tcx, value: ty }
+                        .to_string(),
                     span: None,
                     kind: UnderspecifiedArgKind::Type { prefix: ty.prefix_string(self.tcx) },
                     parent: None,
@@ -325,13 +323,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     }
 
                     debug_assert!(!origin.span.is_dummy());
-                    let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::ValueNS);
-                    if let Some(highlight) = highlight {
-                        printer.region_highlight_mode = highlight;
-                    }
-                    ct.print(&mut printer).unwrap();
                     InferenceDiagnosticsData {
-                        name: printer.into_buffer(),
+                        name: Highlighted { highlight, ns: Namespace::ValueNS, tcx, value: ct }
+                            .to_string(),
                         span: Some(origin.span),
                         kind: UnderspecifiedArgKind::Const { is_parameter: false },
                         parent: None,
@@ -343,13 +337,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     // FIXME: Ideally we should look into the generic constant
                     // to figure out which inference var is actually unresolved so that
                     // this path is unreachable.
-                    let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::ValueNS);
-                    if let Some(highlight) = highlight {
-                        printer.region_highlight_mode = highlight;
-                    }
-                    ct.print(&mut printer).unwrap();
                     InferenceDiagnosticsData {
-                        name: printer.into_buffer(),
+                        name: Highlighted { highlight, ns: Namespace::ValueNS, tcx, value: ct }
+                            .to_string(),
                         span: None,
                         kind: UnderspecifiedArgKind::Const { is_parameter: false },
                         parent: None,
@@ -422,7 +412,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         should_label_span: bool,
     ) -> Diag<'a> {
         let arg = self.resolve_vars_if_possible(arg);
-        let arg_data = self.extract_inference_diagnostics_data(arg, None);
+        let arg_data =
+            self.extract_inference_diagnostics_data(arg, ty::print::RegionHighlightMode::default());
 
         let Some(typeck_results) = &self.typeck_results else {
             // If we don't have any typeck results we're outside

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

@@ -21,9 +21,10 @@ use crate::traits::{ObligationCause, ObligationCauseCode};
 // HACK(eddyb) maybe move this in a more central location.
 #[derive(Copy, Clone)]
 pub struct Highlighted<'tcx, T> {
-    tcx: TyCtxt<'tcx>,
-    highlight: RegionHighlightMode<'tcx>,
-    value: T,
+    pub tcx: TyCtxt<'tcx>,
+    pub highlight: RegionHighlightMode<'tcx>,
+    pub value: T,
+    pub ns: Namespace,
 }
 
 impl<'tcx, T> IntoDiagArg for Highlighted<'tcx, T>
@@ -37,7 +38,7 @@ where
 
 impl<'tcx, T> Highlighted<'tcx, T> {
     fn map<U>(self, f: impl FnOnce(T) -> U) -> Highlighted<'tcx, U> {
-        Highlighted { tcx: self.tcx, highlight: self.highlight, value: f(self.value) }
+        Highlighted { tcx: self.tcx, highlight: self.highlight, value: f(self.value), ns: self.ns }
     }
 }
 
@@ -46,7 +47,7 @@ where
     T: for<'a> Print<'tcx, FmtPrinter<'a, 'tcx>>,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut printer = ty::print::FmtPrinter::new(self.tcx, Namespace::TypeNS);
+        let mut printer = ty::print::FmtPrinter::new(self.tcx, self.ns);
         printer.region_highlight_mode = self.highlight;
 
         self.value.print(&mut printer)?;
@@ -381,6 +382,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
             tcx: self.tcx(),
             highlight: RegionHighlightMode::default(),
             value: trait_ref,
+            ns: Namespace::TypeNS,
         };
 
         let same_self_type = actual_trait_ref.self_ty() == expected_trait_ref.self_ty();

compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs

@@ -2,18 +2,19 @@
 
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
-use rustc_hir::def::Res;
+use rustc_hir::def::{Namespace, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::traits::ObligationCauseCode;
 use rustc_middle::ty::error::ExpectedFound;
 use rustc_middle::ty::print::RegionHighlightMode;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitor};
+use rustc_middle::ty::{self, TyCtxt, TypeVisitable};
 use rustc_span::Span;
 use tracing::debug;
 
 use crate::error_reporting::infer::nice_region_error::NiceRegionError;
+use crate::error_reporting::infer::nice_region_error::placeholder_error::Highlighted;
 use crate::errors::{ConsiderBorrowingParamHelp, RelationshipHelp, TraitImplDiff};
 use crate::infer::{RegionResolutionError, Subtype, ValuePairs};
 
@@ -32,19 +33,14 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             _,
         ) = error.clone()
             && let (Subtype(sup_trace), Subtype(sub_trace)) = (&sup_origin, &sub_origin)
-            && let ObligationCauseCode::CompareImplItem { trait_item_def_id, .. } =
+            && let &ObligationCauseCode::CompareImplItem { trait_item_def_id, .. } =
                 sub_trace.cause.code()
             && sub_trace.values == sup_trace.values
             && let ValuePairs::PolySigs(ExpectedFound { expected, found }) = sub_trace.values
         {
             // FIXME(compiler-errors): Don't like that this needs `Ty`s, but
             // all of the region highlighting machinery only deals with those.
-            let guar = self.emit_err(
-                var_origin.span(),
-                Ty::new_fn_ptr(self.cx.tcx, expected),
-                Ty::new_fn_ptr(self.cx.tcx, found),
-                *trait_item_def_id,
-            );
+            let guar = self.emit_err(var_origin.span(), expected, found, trait_item_def_id);
             return Some(guar);
         }
         None
@@ -53,11 +49,11 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
     fn emit_err(
         &self,
         sp: Span,
-        expected: Ty<'tcx>,
-        found: Ty<'tcx>,
-        trait_def_id: DefId,
+        expected: ty::PolyFnSig<'tcx>,
+        found: ty::PolyFnSig<'tcx>,
+        trait_item_def_id: DefId,
     ) -> ErrorGuaranteed {
-        let trait_sp = self.tcx().def_span(trait_def_id);
+        let trait_sp = self.tcx().def_span(trait_item_def_id);
 
         // Mark all unnamed regions in the type with a number.
         // This diagnostic is called in response to lifetime errors, so be informative.
@@ -67,10 +63,10 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         }
 
         impl<'tcx> HighlightBuilder<'tcx> {
-            fn build(ty: Ty<'tcx>) -> RegionHighlightMode<'tcx> {
+            fn build(sig: ty::PolyFnSig<'tcx>) -> RegionHighlightMode<'tcx> {
                 let mut builder =
                     HighlightBuilder { highlight: RegionHighlightMode::default(), counter: 1 };
-                builder.visit_ty(ty);
+                sig.visit_with(&mut builder);
                 builder.highlight
             }
         }
@@ -85,16 +81,21 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         }
 
         let expected_highlight = HighlightBuilder::build(expected);
-        let expected = self
-            .cx
-            .extract_inference_diagnostics_data(expected.into(), Some(expected_highlight))
-            .name;
+        let tcx = self.cx.tcx;
+        let expected = Highlighted {
+            highlight: expected_highlight,
+            ns: Namespace::TypeNS,
+            tcx,
+            value: expected,
+        }
+        .to_string();
         let found_highlight = HighlightBuilder::build(found);
         let found =
-            self.cx.extract_inference_diagnostics_data(found.into(), Some(found_highlight)).name;
+            Highlighted { highlight: found_highlight, ns: Namespace::TypeNS, tcx, value: found }
+                .to_string();
 
         // Get the span of all the used type parameters in the method.
-        let assoc_item = self.tcx().associated_item(trait_def_id);
+        let assoc_item = self.tcx().associated_item(trait_item_def_id);
         let mut visitor = TypeParamSpanVisitor { tcx: self.tcx(), types: vec![] };
         match assoc_item.kind {
             ty::AssocKind::Fn => {