Rollup of 6 pull requests

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -245,7 +245,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             let Trait(PolyTraitRef { trait_ref, span: trait_span, .. }, _) = bound else { return; };
             diag.span_note(
                 *trait_span,
-                format!("due to current limitations in the borrow checker, this implies a `'static` lifetime")
+                "due to current limitations in the borrow checker, this implies a `'static` lifetime"
             );
             let Some(generics_fn) = hir.get_generics(self.body.source.def_id().expect_local()) else { return; };
             let Def(_, trait_res_defid) = trait_ref.path.res else { return; };
@@ -277,7 +277,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         if suggestions.len() > 0 {
             suggestions.dedup();
             diag.multipart_suggestion_verbose(
-                format!("consider restricting the type parameter to the `'static` lifetime"),
+                "consider restricting the type parameter to the `'static` lifetime",
                 suggestions,
                 Applicability::MaybeIncorrect,
             );

compiler/rustc_codegen_ssa/src/base.rs

@@ -181,7 +181,7 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                 old_info
             }
         }
-        (_, &ty::Dynamic(ref data, _, _)) => meth::get_vtable(cx, source, data.principal()),
+        (_, ty::Dynamic(data, _, _)) => meth::get_vtable(cx, source, data.principal()),
         _ => bug!("unsized_info: invalid unsizing {:?} -> {:?}", source, target),
     }
 }

compiler/rustc_hir_analysis/src/collect.rs

@@ -1374,7 +1374,7 @@ fn impl_trait_ref(
                 // make astconv happy.
                 let mut path_segments = ast_trait_ref.path.segments.to_vec();
                 let last_segment = path_segments.len() - 1;
-                let mut args = path_segments[last_segment].args().clone();
+                let mut args = *path_segments[last_segment].args();
                 let last_arg = args.args.len() - 1;
                 assert!(matches!(args.args[last_arg], hir::GenericArg::Const(anon_const) if tcx.has_attr(anon_const.value.def_id, sym::rustc_host)));
                 args.args = &args.args[..args.args.len() - 1];

compiler/rustc_hir_typeck/src/demand.rs

@@ -644,7 +644,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             if self.can_eq(self.param_env, ty, expected) {
                                 err.span_label(
                                     ex.span,
-                                    format!("expected because of this `break`"),
+                                    "expected because of this `break`",
                                 );
                                 exit = true;
                             }

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

@@ -621,7 +621,7 @@ fn foo(&self) -> Self::T { String::new() }
                         {
                             diag.span_label(
                                 item.span,
-                                format!("associated type is `default` and may be overridden"),
+                                "associated type is `default` and may be overridden",
                             );
                             return true;
                         }

compiler/rustc_middle/src/mir/pretty.rs

@@ -1146,10 +1146,10 @@ fn post_fmt_projection(projection: &[PlaceElem<'_>], fmt: &mut Formatter<'_>) ->
             ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => {
                 write!(fmt, "[-{offset:?} of {min_length:?}]")?;
             }
-            ProjectionElem::Subslice { from, to, from_end: true } if to == 0 => {
+            ProjectionElem::Subslice { from, to: 0, from_end: true } => {
                 write!(fmt, "[{from:?}:]")?;
             }
-            ProjectionElem::Subslice { from, to, from_end: true } if from == 0 => {
+            ProjectionElem::Subslice { from: 0, to, from_end: true } => {
                 write!(fmt, "[:-{to:?}]")?;
             }
             ProjectionElem::Subslice { from, to, from_end: true } => {

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -740,9 +740,7 @@ fn non_exhaustive_match<'p, 'tcx>(
                         ));
                 }
             } else if ty == cx.tcx.types.str_ {
-                err.note(format!(
-                    "`&str` cannot be matched exhaustively, so a wildcard `_` is necessary",
-                ));
+                err.note("`&str` cannot be matched exhaustively, so a wildcard `_` is necessary");
             } else if cx.is_foreign_non_exhaustive_enum(ty) {
                 err.note(format!("`{ty}` is marked as non-exhaustive, so a wildcard `_` is necessary to match exhaustively"));
             }

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -763,7 +763,7 @@ pub(super) fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span>
         // and `_1` is the `Place` for `somenum`.
         //
         // If and when the Issue is resolved, remove this special case match pattern:
-        StatementKind::FakeRead(box (cause, _)) if cause == FakeReadCause::ForGuardBinding => None,
+        StatementKind::FakeRead(box (FakeReadCause::ForGuardBinding, _)) => None,
 
         // Retain spans from all other statements
         StatementKind::FakeRead(box (_, _)) // Not including `ForGuardBinding`

compiler/rustc_mir_transform/src/large_enums.rs

@@ -54,11 +54,8 @@ impl EnumSizeOpt {
         let layout = tcx.layout_of(param_env.and(ty)).ok()?;
         let variants = match &layout.variants {
             Variants::Single { .. } => return None,
-            Variants::Multiple { tag_encoding, .. }
-                if matches!(tag_encoding, TagEncoding::Niche { .. }) =>
-            {
-                return None;
-            }
+            Variants::Multiple { tag_encoding: TagEncoding::Niche { .. }, .. } => return None,
+
             Variants::Multiple { variants, .. } if variants.len() <= 1 => return None,
             Variants::Multiple { variants, .. } => variants,
         };

compiler/rustc_parse/messages.ftl

@@ -509,7 +509,7 @@ parse_maybe_fn_typo_with_impl = you might have meant to write `impl` instead of
 
 parse_maybe_recover_from_bad_qpath_stage_2 =
     missing angle brackets in associated item path
-    .suggestion = try: `{$ty}`
+    .suggestion = types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
 
 parse_maybe_recover_from_bad_type_plus =
     expected a path on the left-hand side of `+`, not `{$ty}`

compiler/rustc_parse/src/errors.rs

@@ -59,9 +59,18 @@ pub(crate) enum BadTypePlusSub {
 #[diag(parse_maybe_recover_from_bad_qpath_stage_2)]
 pub(crate) struct BadQPathStage2 {
     #[primary_span]
-    #[suggestion(code = "", applicability = "maybe-incorrect")]
     pub span: Span,
-    pub ty: String,
+    #[subdiagnostic]
+    pub wrap: WrapType,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(parse_suggestion, applicability = "machine-applicable")]
+pub(crate) struct WrapType {
+    #[suggestion_part(code = "<")]
+    pub lo: Span,
+    #[suggestion_part(code = ">")]
+    pub hi: Span,
 }
 
 #[derive(Diagnostic)]

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -16,7 +16,7 @@ use crate::errors::{
     StructLiteralBodyWithoutPath, StructLiteralBodyWithoutPathSugg, StructLiteralNeedingParens,
     StructLiteralNeedingParensSugg, SuggAddMissingLetStmt, SuggEscapeIdentifier, SuggRemoveComma,
     TernaryOperator, UnexpectedConstInGenericParam, UnexpectedConstParamDeclaration,
-    UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead,
+    UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets, UseEqInstead, WrapType,
 };
 
 use crate::fluent_generated as fluent;
@@ -1589,10 +1589,9 @@ impl<'a> Parser<'a> {
         self.parse_path_segments(&mut path.segments, T::PATH_STYLE, None)?;
         path.span = ty_span.to(self.prev_token.span);
 
-        let ty_str = self.span_to_snippet(ty_span).unwrap_or_else(|_| pprust::ty_to_string(&ty));
         self.sess.emit_err(BadQPathStage2 {
-            span: path.span,
-            ty: format!("<{}>::{}", ty_str, pprust::path_to_string(&path)),
+            span: ty_span,
+            wrap: WrapType { lo: ty_span.shrink_to_lo(), hi: ty_span.shrink_to_hi() },
         });
 
         let path_span = ty_span.shrink_to_hi(); // Use an empty path since `position == 0`.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -186,7 +186,7 @@ impl<'a: 'ast, 'ast, 'tcx> LateResolutionVisitor<'a, '_, 'ast, 'tcx> {
                 fallback_label: format!("not a {expected}"),
                 span,
                 span_label: match res {
-                    Res::Def(kind, def_id) if kind == DefKind::TyParam => {
+                    Res::Def(DefKind::TyParam, def_id) => {
                         Some((self.r.def_span(def_id), "found this type parameter"))
                     }
                     _ => None,

compiler/rustc_span/src/lib.rs

@@ -1753,7 +1753,7 @@ impl SourceFile {
         // is recorded.
         let diff = match self.normalized_pos.binary_search_by(|np| np.pos.cmp(&pos)) {
             Ok(i) => self.normalized_pos[i].diff,
-            Err(i) if i == 0 => 0,
+            Err(0) => 0,
             Err(i) => self.normalized_pos[i - 1].diff,
         };
 
@@ -1775,7 +1775,7 @@ impl SourceFile {
             .binary_search_by(|np| (np.pos.0 + np.diff).cmp(&(self.start_pos.0 + offset)))
         {
             Ok(i) => self.normalized_pos[i].diff,
-            Err(i) if i == 0 => 0,
+            Err(0) => 0,
             Err(i) => self.normalized_pos[i - 1].diff,
         };
 

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -3211,7 +3211,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let name = match self.tcx.opaque_type_origin(def_id.expect_local()) {
             hir::OpaqueTyOrigin::FnReturn(_) | hir::OpaqueTyOrigin::AsyncFn(_) => {
-                format!("opaque type")
+                "opaque type".to_string()
             }
             hir::OpaqueTyOrigin::TyAlias { .. } => {
                 format!("`{}`", self.tcx.def_path_debug_str(def_id))

compiler/stable_mir/src/fold.rs

@@ -81,7 +81,7 @@ impl Foldable for UnevaluatedConst {
 
 impl Foldable for ConstDef {
     fn super_fold<V: Folder>(&self, _folder: &mut V) -> ControlFlow<V::Break, Self> {
-        ControlFlow::Continue(self.clone())
+        ControlFlow::Continue(*self)
     }
 }
 
@@ -96,7 +96,7 @@ impl<T: Foldable> Foldable for Option<T> {
 
 impl Foldable for Promoted {
     fn super_fold<V: Folder>(&self, _folder: &mut V) -> ControlFlow<V::Break, Self> {
-        ControlFlow::Continue(self.clone())
+        ControlFlow::Continue(*self)
     }
 }
 

library/core/src/cmp.rs

@@ -291,9 +291,9 @@ pub macro PartialEq($item:item) {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_diagnostic_item = "Eq"]
 pub trait Eq: PartialEq<Self> {
-    // this method is used solely by #[deriving] to assert
-    // that every component of a type implements #[deriving]
-    // itself, the current deriving infrastructure means doing this
+    // this method is used solely by #[derive(Eq)] to assert
+    // that every component of a type implements `Eq`
+    // itself. The current deriving infrastructure means doing this
     // assertion without using a method on this trait is nearly
     // impossible.
     //

library/core/src/fmt/mod.rs

@@ -112,9 +112,9 @@ pub trait Write {
     ///
     /// # Errors
     ///
-    /// This function will return an instance of [`Error`] on error.
+    /// This function will return an instance of [`std::fmt::Error`][Error] on error.
     ///
-    /// The purpose of std::fmt::Error is to abort the formatting operation when the underlying
+    /// The purpose of that error is to abort the formatting operation when the underlying
     /// destination encounters some error preventing it from accepting more text; it should
     /// generally be propagated rather than handled, at least when implementing formatting traits.
     ///