Auto merge of #119797 - matthiaskrgr:rollup-nn2lt39, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #106893 (Explain base expression for struct update syntax)
 - #119769 (rustdoc: offset generic args of cross-crate trait object types when cleaning)
 - #119772 (Fix an ICE that occurs after an error has already been reported)
 - #119782 (rint intrinsics: caution against actually trying to check for floating-point exceptions)

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

compiler/rustc_ast_lowering/messages.ftl

@@ -35,7 +35,7 @@ ast_lowering_bad_return_type_notation_output =
 
 ast_lowering_base_expression_double_dot =
     base expression required after `..`
-    .label = add a base expression here
+    .suggestion = add a base expression here
 
 ast_lowering_clobber_abi_not_supported =
     `clobber_abi` is not supported on this target

compiler/rustc_ast_lowering/src/errors.rs

@@ -114,10 +114,10 @@ pub struct UnderscoreExprLhsAssign {
 }
 
 #[derive(Diagnostic, Clone, Copy)]
-#[diag(ast_lowering_base_expression_double_dot)]
+#[diag(ast_lowering_base_expression_double_dot, code = "E0797")]
 pub struct BaseExpressionDoubleDot {
     #[primary_span]
-    #[label]
+    #[suggestion(code = "/* expr */", applicability = "has-placeholders", style = "verbose")]
     pub span: Span,
 }
 

compiler/rustc_error_codes/src/error_codes.rs

@@ -516,6 +516,7 @@ E0793: include_str!("./error_codes/E0793.md"),
 E0794: include_str!("./error_codes/E0794.md"),
 E0795: include_str!("./error_codes/E0795.md"),
 E0796: include_str!("./error_codes/E0796.md"),
+E0797: include_str!("./error_codes/E0797.md"),
 }
 
 // Undocumented removed error codes. Note that many removed error codes are kept in the list above

compiler/rustc_error_codes/src/error_codes/E0797.md

@@ -0,0 +1,26 @@
+Struct update syntax was used without a base expression.
+
+Erroneous code example:
+
+```compile_fail,E0797
+struct Foo {
+    fizz: u8,
+    buzz: u8
+}
+
+let f1 = Foo { fizz: 10, buzz: 1};
+let f2 = Foo { fizz: 10, .. }; // error
+```
+
+Using struct update syntax requires a 'base expression'.
+This will be used to fill remaining fields.
+
+```
+struct Foo {
+    fizz: u8,
+    buzz: u8
+}
+
+let f1 = Foo { fizz: 10, buzz: 1};
+let f2 = Foo { fizz: 10, ..f1 };
+```

compiler/rustc_transmute/src/layout/tree.rs

@@ -199,6 +199,7 @@ pub(crate) mod rustc {
             match err {
                 LayoutError::Unknown(..) | LayoutError::ReferencesError(..) => Self::UnknownLayout,
                 LayoutError::SizeOverflow(..) => Self::SizeOverflow,
+                LayoutError::Cycle(err) => Self::TypeError(*err),
                 err => unimplemented!("{:?}", err),
             }
         }

library/core/src/intrinsics.rs

@@ -1787,6 +1787,8 @@ extern "rust-intrinsic" {
     /// so this rounds half-way cases to the number with an even least significant digit.
     ///
     /// May raise an inexact floating-point exception if the argument is not an integer.
+    /// However, Rust assumes floating-point exceptions cannot be observed, so this is not something that
+    /// can actually be used from Rust code.
     ///
     /// The stabilized version of this intrinsic is
     /// [`f32::round_ties_even`](../../std/primitive.f32.html#method.round_ties_even)
@@ -1796,6 +1798,8 @@ extern "rust-intrinsic" {
     /// so this rounds half-way cases to the number with an even least significant digit.
     ///
     /// May raise an inexact floating-point exception if the argument is not an integer.
+    /// However, Rust assumes floating-point exceptions cannot be observed, so this is not something that
+    /// can actually be used from Rust code.
     ///
     /// The stabilized version of this intrinsic is
     /// [`f64::round_ties_even`](../../std/primitive.f64.html#method.round_ties_even)

src/librustdoc/clean/mod.rs

@@ -207,8 +207,13 @@ pub(crate) fn clean_trait_ref_with_bindings<'tcx>(
         span_bug!(cx.tcx.def_span(trait_ref.def_id()), "`TraitRef` had unexpected kind {kind:?}");
     }
     inline::record_extern_fqn(cx, trait_ref.def_id(), kind);
-    let path =
-        external_path(cx, trait_ref.def_id(), true, bindings, trait_ref.map_bound(|tr| tr.args));
+    let path = clean_middle_path(
+        cx,
+        trait_ref.def_id(),
+        true,
+        bindings,
+        trait_ref.map_bound(|tr| tr.args),
+    );
 
     debug!(?trait_ref);
 
@@ -467,7 +472,7 @@ fn projection_to_path_segment<'tcx>(
     PathSegment {
         name: item.name,
         args: GenericArgs::AngleBracketed {
-            args: ty_args_to_args(
+            args: clean_middle_generic_args(
                 cx,
                 ty.map_bound(|ty| &ty.args[generics.parent_count..]),
                 false,
@@ -1903,7 +1908,7 @@ fn normalize<'tcx>(
 
 fn clean_trait_object_lifetime_bound<'tcx>(
     region: ty::Region<'tcx>,
-    container: Option<ContainerTy<'tcx>>,
+    container: Option<ContainerTy<'_, 'tcx>>,
     preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
     tcx: TyCtxt<'tcx>,
 ) -> Option<Lifetime> {
@@ -1932,7 +1937,7 @@ fn clean_trait_object_lifetime_bound<'tcx>(
 
 fn can_elide_trait_object_lifetime_bound<'tcx>(
     region: ty::Region<'tcx>,
-    container: Option<ContainerTy<'tcx>>,
+    container: Option<ContainerTy<'_, 'tcx>>,
     preds: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
     tcx: TyCtxt<'tcx>,
 ) -> bool {
@@ -1979,21 +1984,22 @@ fn can_elide_trait_object_lifetime_bound<'tcx>(
 }
 
 #[derive(Debug)]
-pub(crate) enum ContainerTy<'tcx> {
+pub(crate) enum ContainerTy<'a, 'tcx> {
     Ref(ty::Region<'tcx>),
     Regular {
         ty: DefId,
-        args: ty::Binder<'tcx, &'tcx [ty::GenericArg<'tcx>]>,
-        has_self: bool,
+        /// The arguments *have* to contain an arg for the self type if the corresponding generics
+        /// contain a self type.
+        args: ty::Binder<'tcx, &'a [ty::GenericArg<'tcx>]>,
         arg: usize,
     },
 }
 
-impl<'tcx> ContainerTy<'tcx> {
+impl<'tcx> ContainerTy<'_, 'tcx> {
     fn object_lifetime_default(self, tcx: TyCtxt<'tcx>) -> ObjectLifetimeDefault<'tcx> {
         match self {
             Self::Ref(region) => ObjectLifetimeDefault::Arg(region),
-            Self::Regular { ty: container, args, has_self, arg: index } => {
+            Self::Regular { ty: container, args, arg: index } => {
                 let (DefKind::Struct
                 | DefKind::Union
                 | DefKind::Enum
@@ -2006,14 +2012,7 @@ impl<'tcx> ContainerTy<'tcx> {
                 let generics = tcx.generics_of(container);
                 debug_assert_eq!(generics.parent_count, 0);
 
-                // If the container is a trait object type, the arguments won't contain the self type but the
-                // generics of the corresponding trait will. In such a case, offset the index by one.
-                // For comparison, if the container is a trait inside a bound, the arguments do contain the
-                // self type.
-                let offset =
-                    if !has_self && generics.parent.is_none() && generics.has_self { 1 } else { 0 };
-                let param = generics.params[index + offset].def_id;
-
+                let param = generics.params[index].def_id;
                 let default = tcx.object_lifetime_default(param);
                 match default {
                     rbv::ObjectLifetimeDefault::Param(lifetime) => {
@@ -2045,7 +2044,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
     bound_ty: ty::Binder<'tcx, Ty<'tcx>>,
     cx: &mut DocContext<'tcx>,
     parent_def_id: Option<DefId>,
-    container: Option<ContainerTy<'tcx>>,
+    container: Option<ContainerTy<'_, 'tcx>>,
 ) -> Type {
     let bound_ty = normalize(cx, bound_ty).unwrap_or(bound_ty);
     match *bound_ty.skip_binder().kind() {
@@ -2096,12 +2095,12 @@ pub(crate) fn clean_middle_ty<'tcx>(
                 AdtKind::Enum => ItemType::Enum,
             };
             inline::record_extern_fqn(cx, did, kind);
-            let path = external_path(cx, did, false, ThinVec::new(), bound_ty.rebind(args));
+            let path = clean_middle_path(cx, did, false, ThinVec::new(), bound_ty.rebind(args));
             Type::Path { path }
         }
         ty::Foreign(did) => {
             inline::record_extern_fqn(cx, did, ItemType::ForeignType);
-            let path = external_path(
+            let path = clean_middle_path(
                 cx,
                 did,
                 false,
@@ -2132,7 +2131,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
             let mut bounds = dids
                 .map(|did| {
                     let empty = ty::Binder::dummy(ty::GenericArgs::empty());
-                    let path = external_path(cx, did, false, ThinVec::new(), empty);
+                    let path = clean_middle_path(cx, did, false, ThinVec::new(), empty);
                     inline::record_extern_fqn(cx, did, ItemType::Trait);
                     PolyTrait { trait_: path, generic_params: Vec::new() }
                 })
@@ -2171,7 +2170,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
                 .collect();
             let late_bound_regions = late_bound_regions.into_iter().collect();
 
-            let path = external_path(cx, did, false, bindings, args);
+            let path = clean_middle_path(cx, did, false, bindings, args);
             bounds.insert(0, PolyTrait { trait_: path, generic_params: late_bound_regions });
 
             DynTrait(bounds, lifetime)
@@ -2193,7 +2192,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
                 assoc: PathSegment {
                     name: cx.tcx.associated_item(def_id).name,
                     args: GenericArgs::AngleBracketed {
-                        args: ty_args_to_args(
+                        args: clean_middle_generic_args(
                             cx,
                             alias_ty.map_bound(|ty| ty.args.as_slice()),
                             true,
@@ -2213,7 +2212,7 @@ pub(crate) fn clean_middle_ty<'tcx>(
             if cx.tcx.features().lazy_type_alias {
                 // Weak type alias `data` represents the `type X` in `type X = Y`. If we need `Y`,
                 // we need to use `type_of`.
-                let path = external_path(
+                let path = clean_middle_path(
                     cx,
                     data.def_id,
                     false,
@@ -2243,7 +2242,8 @@ pub(crate) fn clean_middle_ty<'tcx>(
         ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
             // If it's already in the same alias, don't get an infinite loop.
             if cx.current_type_aliases.contains_key(&def_id) {
-                let path = external_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
+                let path =
+                    clean_middle_path(cx, def_id, false, ThinVec::new(), bound_ty.rebind(args));
                 Type::Path { path }
             } else {
                 *cx.current_type_aliases.entry(def_id).or_insert(0) += 1;

src/librustdoc/clean/types.rs

@@ -36,7 +36,7 @@ use rustc_target::abi::VariantIdx;
 use rustc_target::spec::abi::Abi;
 
 use crate::clean::cfg::Cfg;
-use crate::clean::external_path;
+use crate::clean::clean_middle_path;
 use crate::clean::inline::{self, print_inlined_const};
 use crate::clean::utils::{is_literal_expr, print_evaluated_const};
 use crate::core::DocContext;
@@ -1258,7 +1258,7 @@ impl GenericBound {
     fn sized_with(cx: &mut DocContext<'_>, modifier: hir::TraitBoundModifier) -> GenericBound {
         let did = cx.tcx.require_lang_item(LangItem::Sized, None);
         let empty = ty::Binder::dummy(ty::GenericArgs::empty());
-        let path = external_path(cx, did, false, ThinVec::new(), empty);
+        let path = clean_middle_path(cx, did, false, ThinVec::new(), empty);
         inline::record_extern_fqn(cx, did, ItemType::Trait);
         GenericBound::TraitBound(PolyTrait { trait_: path, generic_params: Vec::new() }, modifier)
     }