Auto merge of rust-lang#87923 - JohnTitor:rollup-id54fyz, r=JohnTitor

Rollup of 14 pull requests

Successful merges:

 - rust-lang#86840 (Constify implementations of `(Try)From` for int types)
 - rust-lang#87582 (Implement `Printer` for `&mut SymbolPrinter`)
 - rust-lang#87636 (Added the `Option::unzip()` method)
 - rust-lang#87700 (Expand explanation of E0530)
 - rust-lang#87811 (Do not ICE on HIR based WF check when involving lifetimes)
 - rust-lang#87848 (removed references to parent/child from std::thread documentation)
 - rust-lang#87854 (correctly handle enum variants in `opt_const_param_of`)
 - rust-lang#87861 (Fix heading colours in Ayu theme)
 - rust-lang#87865 (Clarify terms in rustdoc book)
 - rust-lang#87876 (add `windows` count test)
 - rust-lang#87880 (Remove duplicate trait bounds in `rustc_data_structures::graph`)
 - rust-lang#87881 (Proper table row formatting in platform support)
 - rust-lang#87889 (Use smaller spans when suggesting method call disambiguation)
 - rust-lang#87895 (typeck: don't suggest inaccessible fields in struct literals and suggest ignoring inaccessible fields in struct patterns)

Failed merges:

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

Author: bors

compiler/rustc_data_structures/src/graph/mod.rs

@@ -60,18 +60,13 @@ pub trait WithStartNode: DirectedGraph {
 }
 
 pub trait ControlFlowGraph:
-    DirectedGraph + WithStartNode + WithPredecessors + WithStartNode + WithSuccessors + WithNumNodes
+    DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors + WithNumNodes
 {
     // convenient trait
 }
 
 impl<T> ControlFlowGraph for T where
-    T: DirectedGraph
-        + WithStartNode
-        + WithPredecessors
-        + WithStartNode
-        + WithSuccessors
-        + WithNumNodes
+    T: DirectedGraph + WithStartNode + WithPredecessors + WithSuccessors + WithNumNodes
 {
 }
 

compiler/rustc_error_codes/src/error_codes/E0530.md

@@ -1,32 +1,57 @@
 A binding shadowed something it shouldn't.
 
-Erroneous code example:
+A match arm or a variable has a name that is already used by
+something else, e.g.
+
+* struct name
+* enum variant
+* static
+* associated constant
+
+This error may also happen when an enum variant *with fields* is used
+in a pattern, but without its fields.
+
+```compile_fail
+enum Enum {
+    WithField(i32)
+}
+
+use Enum::*;
+match WithField(1) {
+    WithField => {} // error: missing (_)
+}
+```
+
+Match bindings cannot shadow statics:
 
 ```compile_fail,E0530
 static TEST: i32 = 0;
 
-let r: (i32, i32) = (0, 0);
+let r = 123;
 match r {
-    TEST => {} // error: match bindings cannot shadow statics
+    TEST => {} // error: name of a static
 }
 ```
 
-To fix this error, just change the binding's name in order to avoid shadowing
-one of the following:
+Fixed examples:
 
-* struct name
-* struct/enum variant
-* static
-* const
-* associated const
+```
+static TEST: i32 = 0;
 
-Fixed example:
+let r = 123;
+match r {
+    some_value => {} // ok!
+}
+```
+
+or
 
 ```
-static TEST: i32 = 0;
+const TEST: i32 = 0; // const, not static
 
-let r: (i32, i32) = (0, 0);
+let r = 123;
 match r {
-    something => {} // ok!
+    TEST => {} // const is ok!
+    other_values => {}
 }
 ```

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -55,7 +55,8 @@ pub(super) fn mangle(
 
     let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate);
 
-    let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false }
+    let mut printer = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false };
+    printer
         .print_def_path(
             def_id,
             if let ty::InstanceDef::DropGlue(_, _) = instance.def {
@@ -198,7 +199,7 @@ struct SymbolPrinter<'tcx> {
 // `PrettyPrinter` aka pretty printing of e.g. types in paths,
 // symbol names should have their own printing machinery.
 
-impl Printer<'tcx> for SymbolPrinter<'tcx> {
+impl Printer<'tcx> for &mut SymbolPrinter<'tcx> {
     type Error = fmt::Error;
 
     type Path = Self;
@@ -242,7 +243,7 @@ impl Printer<'tcx> for SymbolPrinter<'tcx> {
         Ok(self)
     }
 
-    fn print_const(mut self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
+    fn print_const(self, ct: &'tcx ty::Const<'tcx>) -> Result<Self::Const, Self::Error> {
         // only print integers
         if let ty::ConstKind::Value(ConstValue::Scalar(Scalar::Int { .. })) = ct.val {
             if ct.ty.is_integral() {
@@ -253,7 +254,7 @@ impl Printer<'tcx> for SymbolPrinter<'tcx> {
         Ok(self)
     }
 
-    fn path_crate(mut self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
+    fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error> {
         self.write_str(&self.tcx.crate_name(cnum).as_str())?;
         Ok(self)
     }
@@ -344,7 +345,7 @@ impl Printer<'tcx> for SymbolPrinter<'tcx> {
     }
 }
 
-impl PrettyPrinter<'tcx> for SymbolPrinter<'tcx> {
+impl PrettyPrinter<'tcx> for &mut SymbolPrinter<'tcx> {
     fn region_should_not_be_omitted(&self, _region: ty::Region<'_>) -> bool {
         false
     }

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

@@ -245,9 +245,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 if let ObligationCauseCode::WellFormed(Some(wf_loc)) =
                     root_obligation.cause.code.peel_derives()
                 {
-                    if let Some(cause) =
-                        self.tcx.diagnostic_hir_wf_check((obligation.predicate, wf_loc.clone()))
-                    {
+                    if let Some(cause) = self.tcx.diagnostic_hir_wf_check((
+                        tcx.erase_regions(obligation.predicate),
+                        wf_loc.clone(),
+                    )) {
                         obligation.cause = cause;
                         span = obligation.cause.span;
                     }

compiler/rustc_typeck/src/check/expr.rs

@@ -1313,15 +1313,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .emit();
             }
         } else if check_completeness && !error_happened && !remaining_fields.is_empty() {
-            let no_accessible_remaining_fields = remaining_fields
-                .iter()
-                .find(|(_, (_, field))| {
-                    field.vis.is_accessible_from(tcx.parent_module(expr_id).to_def_id(), tcx)
-                })
-                .is_none();
+            let inaccessible_remaining_fields = remaining_fields.iter().any(|(_, (_, field))| {
+                !field.vis.is_accessible_from(tcx.parent_module(expr_id).to_def_id(), tcx)
+            });
 
-            if no_accessible_remaining_fields {
-                self.report_no_accessible_fields(adt_ty, span);
+            if inaccessible_remaining_fields {
+                self.report_inaccessible_fields(adt_ty, span);
             } else {
                 self.report_missing_fields(adt_ty, span, remaining_fields);
             }
@@ -1398,7 +1395,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         .emit();
     }
 
-    /// Report an error for a struct field expression when there are no visible fields.
+    /// Report an error for a struct field expression when there are invisible fields.
     ///
     /// ```text
     /// error: cannot construct `Foo` with struct literal syntax due to inaccessible fields
@@ -1409,7 +1406,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ///
     /// error: aborting due to previous error
     /// ```
-    fn report_no_accessible_fields(&self, adt_ty: Ty<'tcx>, span: Span) {
+    fn report_inaccessible_fields(&self, adt_ty: Ty<'tcx>, span: Span) {
         self.tcx.sess.span_err(
             span,
             &format!(

compiler/rustc_typeck/src/check/method/suggest.rs

@@ -1695,8 +1695,8 @@ fn print_disambiguation_help(
     source_map: &source_map::SourceMap,
 ) {
     let mut applicability = Applicability::MachineApplicable;
-    let sugg_args = if let (ty::AssocKind::Fn, Some(args)) = (kind, args) {
-        format!(
+    let (span, sugg) = if let (ty::AssocKind::Fn, Some(args)) = (kind, args) {
+        let args = format!(
             "({}{})",
             if rcvr_ty.is_region_ptr() {
                 if rcvr_ty.is_mutable_ptr() { "&mut " } else { "&" }
@@ -1710,12 +1710,12 @@ fn print_disambiguation_help(
                 }))
                 .collect::<Vec<_>>()
                 .join(", "),
-        )
+        );
+        (span, format!("{}::{}{}", trait_name, item_name, args))
     } else {
-        String::new()
+        (span.with_hi(item_name.span.lo()), format!("{}::", trait_name))
     };
-    let sugg = format!("{}::{}{}", trait_name, item_name, sugg_args);
-    err.span_suggestion(
+    err.span_suggestion_verbose(
         span,
         &format!(
             "disambiguate the {} for {}",

compiler/rustc_typeck/src/check/pat.rs

@@ -1250,15 +1250,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 tcx.sess.struct_span_err(pat.span, "`..` cannot be used in union patterns").emit();
             }
         } else if !etc && !unmentioned_fields.is_empty() {
-            let no_accessible_unmentioned_fields = !unmentioned_fields.iter().any(|(field, _)| {
-                field.vis.is_accessible_from(tcx.parent_module(pat.hir_id).to_def_id(), tcx)
-            });
+            let accessible_unmentioned_fields: Vec<_> = unmentioned_fields
+                .iter()
+                .copied()
+                .filter(|(field, _)| {
+                    field.vis.is_accessible_from(tcx.parent_module(pat.hir_id).to_def_id(), tcx)
+                })
+                .collect();
 
-            if no_accessible_unmentioned_fields {
+            if accessible_unmentioned_fields.is_empty() {
                 unmentioned_err = Some(self.error_no_accessible_fields(pat, &fields));
             } else {
-                unmentioned_err =
-                    Some(self.error_unmentioned_fields(pat, &unmentioned_fields, &fields));
+                unmentioned_err = Some(self.error_unmentioned_fields(
+                    pat,
+                    &accessible_unmentioned_fields,
+                    accessible_unmentioned_fields.len() != unmentioned_fields.len(),
+                    &fields,
+                ));
             }
         }
         match (inexistent_fields_err, unmentioned_err) {
@@ -1583,17 +1591,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         pat: &Pat<'_>,
         unmentioned_fields: &[(&ty::FieldDef, Ident)],
+        have_inaccessible_fields: bool,
         fields: &'tcx [hir::PatField<'tcx>],
     ) -> DiagnosticBuilder<'tcx> {
+        let inaccessible = if have_inaccessible_fields { " and inaccessible fields" } else { "" };
         let field_names = if unmentioned_fields.len() == 1 {
-            format!("field `{}`", unmentioned_fields[0].1)
+            format!("field `{}`{}", unmentioned_fields[0].1, inaccessible)
         } else {
             let fields = unmentioned_fields
                 .iter()
                 .map(|(_, name)| format!("`{}`", name))
                 .collect::<Vec<String>>()
                 .join(", ");
-            format!("fields {}", fields)
+            format!("fields {}{}", fields, inaccessible)
         };
         let mut err = struct_span_err!(
             self.tcx.sess,
@@ -1624,17 +1634,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err.span_suggestion(
             sp,
             &format!(
-                "include the missing field{} in the pattern",
+                "include the missing field{} in the pattern{}",
                 if len == 1 { "" } else { "s" },
+                if have_inaccessible_fields { " and ignore the inaccessible fields" } else { "" }
             ),
             format!(
-                "{}{}{}",
+                "{}{}{}{}",
                 prefix,
                 unmentioned_fields
                     .iter()
                     .map(|(_, name)| name.to_string())
                     .collect::<Vec<_>>()
                     .join(", "),
+                if have_inaccessible_fields { ", .." } else { "" },
                 postfix,
             ),
             Applicability::MachineApplicable,

compiler/rustc_typeck/src/collect/type_of.rs

@@ -190,8 +190,12 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
                 // Try to use the segment resolution if it is valid, otherwise we
                 // default to the path resolution.
                 let res = segment.res.filter(|&r| r != Res::Err).unwrap_or(path.res);
+                use def::CtorOf;
                 let generics = match res {
-                    Res::Def(DefKind::Ctor(..), def_id) => {
+                    Res::Def(DefKind::Ctor(CtorOf::Variant, _), def_id) => tcx.generics_of(
+                        tcx.parent(def_id).and_then(|def_id| tcx.parent(def_id)).unwrap(),
+                    ),
+                    Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Struct, _), def_id) => {
                         tcx.generics_of(tcx.parent(def_id).unwrap())
                     }
                     // Other `DefKind`s don't have generics and would ICE when calling
@@ -200,7 +204,6 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
                         DefKind::Struct
                         | DefKind::Union
                         | DefKind::Enum
-                        | DefKind::Variant
                         | DefKind::Trait
                         | DefKind::OpaqueTy
                         | DefKind::TyAlias

library/core/src/convert/num.rs

@@ -45,7 +45,8 @@ impl_float_to_int!(f64 => u8 u16 u32 u64 u128 usize i8 i16 i32 i64 i128 isize);
 macro_rules! impl_from {
     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
         #[$attr]
-        impl From<$Small> for $Large {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const From<$Small> for $Large {
             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
             // Rustdocs on functions do not.
             #[doc = $doc]
@@ -172,7 +173,8 @@ impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0"
 macro_rules! try_from_unbounded {
     ($source:ty, $($target:ty),*) => {$(
         #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const TryFrom<$source> for $target {
             type Error = TryFromIntError;
 
             /// Try to create the target number type from a source
@@ -190,7 +192,8 @@ macro_rules! try_from_unbounded {
 macro_rules! try_from_lower_bounded {
     ($source:ty, $($target:ty),*) => {$(
         #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const TryFrom<$source> for $target {
             type Error = TryFromIntError;
 
             /// Try to create the target number type from a source
@@ -212,7 +215,8 @@ macro_rules! try_from_lower_bounded {
 macro_rules! try_from_upper_bounded {
     ($source:ty, $($target:ty),*) => {$(
         #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const TryFrom<$source> for $target {
             type Error = TryFromIntError;
 
             /// Try to create the target number type from a source
@@ -234,7 +238,8 @@ macro_rules! try_from_upper_bounded {
 macro_rules! try_from_both_bounded {
     ($source:ty, $($target:ty),*) => {$(
         #[stable(feature = "try_from", since = "1.34.0")]
-        impl TryFrom<$source> for $target {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const TryFrom<$source> for $target {
             type Error = TryFromIntError;
 
             /// Try to create the target number type from a source

library/core/src/lib.rs

@@ -99,6 +99,7 @@
 #![feature(const_slice_from_raw_parts)]
 #![feature(const_slice_ptr_len)]
 #![feature(const_swap)]
+#![feature(const_trait_impl)]
 #![feature(const_type_id)]
 #![feature(const_type_name)]
 #![feature(const_unreachable_unchecked)]