Auto merge of rust-lang#96117 - Dylan-DPC:rollup-5traczf, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - rust-lang#95887 (resolve: Create dummy bindings for all unresolved imports)
 - rust-lang#96023 (couple of clippy::perf fixes)
 - rust-lang#96035 (Update GitHub Actions actions/checkout Version v2 -> v3)
 - rust-lang#96038 (docs: add link from zip to unzip)
 - rust-lang#96047 (:arrow_up: rust-analyzer)
 - rust-lang#96059 (clarify doc(cfg) wording)
 - rust-lang#96081 (Make some `usize`-typed masks definitions agnostic to the size of `usize`)

Failed merges:

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

Author: bors

.github/workflows/ci.yml

@@ -56,7 +56,7 @@ jobs:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
       - name: checkout the source code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 2
       - name: configure the PR in which the error message will be posted
@@ -454,7 +454,7 @@ jobs:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
       - name: checkout the source code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 2
       - name: configure the PR in which the error message will be posted
@@ -567,7 +567,7 @@ jobs:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
       - name: checkout the source code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 2
       - name: configure the PR in which the error message will be posted
@@ -670,7 +670,7 @@ jobs:
     if: "github.event_name == 'push' && github.ref == 'refs/heads/master' && github.repository == 'rust-lang-ci/rust'"
     steps:
       - name: checkout the source code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           fetch-depth: 2
       - name: publish toolstate

compiler/rustc_codegen_llvm/src/debuginfo/metadata/enums/cpp_like.rs

@@ -372,7 +372,6 @@ fn build_union_fields_for_direct_tag_generator<'ll, 'tcx>(
 
     // Build the type node for each field.
     let variant_field_infos: SmallVec<VariantFieldInfo<'ll>> = variant_range
-        .clone()
         .map(|variant_index| {
             let variant_struct_type_di_node = super::build_generator_variant_struct_type_di_node(
                 cx,

compiler/rustc_errors/src/lib.rs

@@ -1208,7 +1208,7 @@ impl HandlerInner {
             (0, 0) => return,
             (0, _) => self.emitter.emit_diagnostic(&Diagnostic::new(
                 Level::Warning,
-                DiagnosticMessage::Str(warnings.to_owned()),
+                DiagnosticMessage::Str(warnings),
             )),
             (_, 0) => {
                 let _ = self.fatal(&errors);

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -590,7 +590,7 @@ impl TtParser {
                 (_, 0) => {
                     // Dump all possible `next_mps` into `cur_mps` for the next iteration. Then
                     // process the next token.
-                    self.cur_mps.extend(self.next_mps.drain(..));
+                    self.cur_mps.append(&mut self.next_mps);
                     parser.to_mut().bump();
                 }
 

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

@@ -844,7 +844,7 @@ fn non_exhaustive_match<'p, 'tcx>(
                     format!(
                         "{}{}{} => todo!()",
                         comma,
-                        snippet.strip_prefix(",").unwrap_or(&snippet),
+                        snippet.strip_prefix(',').unwrap_or(&snippet),
                         pattern
                     ),
                 ));

compiler/rustc_resolve/src/imports.rs

@@ -310,18 +310,23 @@ impl<'a> Resolver<'a> {
         t
     }
 
-    // Define a "dummy" resolution containing a Res::Err as a placeholder for a
-    // failed resolution
+    // Define a dummy resolution containing a `Res::Err` as a placeholder for a failed resolution,
+    // also mark such failed imports as used to avoid duplicate diagnostics.
     fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
-        if let ImportKind::Single { target, .. } = import.kind {
+        if let ImportKind::Single { target, ref target_bindings, .. } = import.kind {
+            if target_bindings.iter().any(|binding| binding.get().is_some()) {
+                return; // Has resolution, do not create the dummy binding
+            }
             let dummy_binding = self.dummy_binding;
             let dummy_binding = self.import(dummy_binding, import);
             self.per_ns(|this, ns| {
                 let key = this.new_key(target, ns);
                 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
             });
-            // Consider erroneous imports used to avoid duplicate diagnostics.
             self.record_use(target, dummy_binding, false);
+        } else if import.imported_module.get().is_none() {
+            import.used.set(true);
+            self.used_imports.insert(import.id);
         }
     }
 }
@@ -386,7 +391,13 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
             .map(|i| (false, i))
             .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
         {
-            if let Some(err) = self.finalize_import(import) {
+            let unresolved_import_error = self.finalize_import(import);
+
+            // If this import is unresolved then create a dummy import
+            // resolution for it so that later resolve stages won't complain.
+            self.r.import_dummy_binding(import);
+
+            if let Some(err) = unresolved_import_error {
                 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
                     if source.name == kw::SelfLower {
                         // Silence `unresolved import` error if E0429 is already emitted
@@ -396,9 +407,6 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                     }
                 }
 
-                // If the error is a single failed import then create a "fake" import
-                // resolution for it so that later resolve stages won't complain.
-                self.r.import_dummy_binding(import);
                 if prev_root_id.as_u32() != 0
                     && prev_root_id.as_u32() != import.root_id.as_u32()
                     && !errors.is_empty()
@@ -418,8 +426,6 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                     prev_root_id = import.root_id;
                 }
             } else if is_indeterminate {
-                // Consider erroneous imports used to avoid duplicate diagnostics.
-                self.r.used_imports.insert(import.id);
                 let path = import_path_to_string(
                     &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
                     &import.kind,
@@ -553,26 +559,23 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                     Err(Undetermined) => indeterminate = true,
                     // Don't update the resolution, because it was never added.
                     Err(Determined) if target.name == kw::Underscore => {}
-                    Err(Determined) => {
+                    Ok(binding) if binding.is_importable() => {
+                        let imported_binding = this.import(binding, import);
+                        target_bindings[ns].set(Some(imported_binding));
+                        this.define(parent, target, ns, imported_binding);
+                    }
+                    source_binding @ (Ok(..) | Err(Determined)) => {
+                        if source_binding.is_ok() {
+                            let msg = format!("`{}` is not directly importable", target);
+                            struct_span_err!(this.session, import.span, E0253, "{}", &msg)
+                                .span_label(import.span, "cannot be imported directly")
+                                .emit();
+                        }
                         let key = this.new_key(target, ns);
                         this.update_resolution(parent, key, |_, resolution| {
                             resolution.single_imports.remove(&Interned::new_unchecked(import));
                         });
                     }
-                    Ok(binding) if !binding.is_importable() => {
-                        let msg = format!("`{}` is not directly importable", target);
-                        struct_span_err!(this.session, import.span, E0253, "{}", &msg)
-                            .span_label(import.span, "cannot be imported directly")
-                            .emit();
-                        // Do not import this illegal binding. Import a dummy binding and pretend
-                        // everything is fine
-                        this.import_dummy_binding(import);
-                    }
-                    Ok(binding) => {
-                        let imported_binding = this.import(binding, import);
-                        target_bindings[ns].set(Some(imported_binding));
-                        this.define(parent, target, ns, imported_binding);
-                    }
                 }
             }
         });
@@ -605,10 +608,6 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         );
         let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
         import.vis.set(orig_vis);
-        if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
-            // Consider erroneous imports used to avoid duplicate diagnostics.
-            self.r.used_imports.insert(import.id);
-        }
         let module = match path_res {
             PathResult::Module(module) => {
                 // Consistency checks, analogous to `finalize_macro_resolutions`.
@@ -872,7 +871,6 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                 })
             } else {
                 // `resolve_ident_in_module` reported a privacy error.
-                self.r.import_dummy_binding(import);
                 None
             };
         }

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

@@ -2724,9 +2724,9 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 &format!(
                     "consider annotating `{}` with `#[derive({})]`",
                     trait_pred.skip_binder().self_ty(),
-                    diagnostic_name.to_string(),
+                    diagnostic_name,
                 ),
-                format!("#[derive({})]\n", diagnostic_name.to_string()),
+                format!("#[derive({})]\n", diagnostic_name),
                 Applicability::MaybeIncorrect,
             );
         }

library/core/benches/ascii/is_ascii.rs

@@ -77,6 +77,6 @@ fn is_ascii_align_to_unrolled(bytes: &[u8]) -> bool {
 
 #[inline]
 fn contains_nonascii(v: usize) -> bool {
-    const NONASCII_MASK: usize = 0x80808080_80808080u64 as usize;
+    const NONASCII_MASK: usize = usize::from_ne_bytes([0x80; core::mem::size_of::<usize>()]);
     (NONASCII_MASK & v) != 0
 }

library/core/src/iter/traits/iterator.rs

@@ -470,6 +470,10 @@ pub trait Iterator {
     /// it will first try to advance the first iterator at most one time and if it still yielded an item
     /// try to advance the second iterator at most one time.
     ///
+    /// To 'undo' the result of zipping up two iterators, see [`unzip`].
+    ///
+    /// [`unzip`]: Iterator::unzip
+    ///
     /// # Examples
     ///
     /// Basic usage:

library/core/src/num/mod.rs

@@ -890,6 +890,27 @@ impl usize {
     widening_impl! { usize, u128, 64, unsigned }
 }
 
+impl usize {
+    /// Returns an `usize` where every byte is equal to `x`.
+    #[inline]
+    pub(crate) const fn repeat_u8(x: u8) -> usize {
+        usize::from_ne_bytes([x; mem::size_of::<usize>()])
+    }
+
+    /// Returns an `usize` where every byte pair is equal to `x`.
+    #[inline]
+    pub(crate) const fn repeat_u16(x: u16) -> usize {
+        let mut r = 0usize;
+        let mut i = 0;
+        while i < mem::size_of::<usize>() {
+            // Use `wrapping_shl` to make it work on targets with 16-bit `usize`
+            r = r.wrapping_shl(16) | (x as usize);
+            i += 2;
+        }
+        r
+    }
+}
+
 /// A classification of floating point numbers.
 ///
 /// This `enum` is used as the return type for [`f32::classify`] and [`f64::classify`]. See