Auto merge of #89984 - matthiaskrgr:rollup-ikmyhmx, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #89738 (ty::pretty: prevent infinite recursion for `extern crate` paths.)
 - #89888 (Make `llvm.download-ci-llvm="if-available"` work for tier 2 targets with host tools)
 - #89945 (Remove a mention to `copy_from_slice` from `clone_from_slice` doc)
 - #89946 (Fix an ICE with TAITs and Future)
 - #89963 (Some "parenthesis" and "parentheses" fixes)
 - #89975 (Add a regression test for #85921)
 - #89977 (Make Result::as_mut const)

Failed merges:

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

Author: bors

compiler/rustc_ast/src/util/parser.rs

@@ -357,13 +357,13 @@ impl ExprPrecedence {
     }
 }
 
-/// In `let p = e`, operators with precedence `<=` this one requires parenthesis in `e`.
+/// In `let p = e`, operators with precedence `<=` this one requires parentheses in `e`.
 pub fn prec_let_scrutinee_needs_par() -> usize {
     AssocOp::LAnd.precedence()
 }
 
 /// Suppose we have `let _ = e` and the `order` of `e`.
-/// Is the `order` such that `e` in `let _ = e` needs parenthesis when it is on the RHS?
+/// Is the `order` such that `e` in `let _ = e` needs parentheses when it is on the RHS?
 ///
 /// Conversely, suppose that we have `(let _ = a) OP b` and `order` is that of `OP`.
 /// Can we print this as `let _ = a OP b`?

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -113,7 +113,7 @@ impl<'a> AstValidator<'a> {
         if sess.opts.unstable_features.is_nightly_build() {
             sess.struct_span_err(expr.span, "`let` expressions are not supported here")
                 .note("only supported directly in conditions of `if`- and `while`-expressions")
-                .note("as well as when nested within `&&` and parenthesis in those conditions")
+                .note("as well as when nested within `&&` and parentheses in those conditions")
                 .emit();
         } else {
             sess.struct_span_err(expr.span, "expected expression, found statement (`let`)")

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1675,7 +1675,7 @@ impl<'a> State<'a> {
         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr))
     }
 
-    // Does `expr` need parenthesis when printed in a condition position?
+    // Does `expr` need parentheses when printed in a condition position?
     //
     // These cases need parens due to the parse error observed in #26461: `if return {}`
     // parses as the erroneous construct `if (return {})`, not `if (return) {}`.

compiler/rustc_hir_pretty/src/lib.rs

@@ -1168,7 +1168,7 @@ impl<'a> State<'a> {
         self.print_expr_cond_paren(expr, Self::cond_needs_par(expr) || npals())
     }
 
-    // Does `expr` need parenthesis when printed in a condition position?
+    // Does `expr` need parentheses when printed in a condition position?
     //
     // These cases need parens due to the parse error observed in #26461: `if return {}`
     // parses as the erroneous construct `if (return {})`, not `if (return) {}`.

compiler/rustc_lint/src/unused.rs

@@ -670,7 +670,7 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// The parenthesis are not needed, and should be removed. This is the
+    /// The parentheses are not needed, and should be removed. This is the
     /// preferred style for writing these expressions.
     pub(super) UNUSED_PARENS,
     Warn,

compiler/rustc_middle/src/ty/error.rs

@@ -769,11 +769,16 @@ fn foo(&self) -> Self::T { String::new() }
     ) -> bool {
         let assoc = self.associated_item(proj_ty.item_def_id);
         if let ty::Opaque(def_id, _) = *proj_ty.self_ty().kind() {
-            let opaque_local_def_id = def_id.expect_local();
-            let opaque_hir_id = self.hir().local_def_id_to_hir_id(opaque_local_def_id);
-            let opaque_hir_ty = match &self.hir().expect_item(opaque_hir_id).kind {
-                hir::ItemKind::OpaqueTy(opaque_hir_ty) => opaque_hir_ty,
-                _ => bug!("The HirId comes from a `ty::Opaque`"),
+            let opaque_local_def_id = def_id.as_local();
+            let opaque_hir_ty = if let Some(opaque_local_def_id) = opaque_local_def_id {
+                let hir = self.hir();
+                let opaque_hir_id = hir.local_def_id_to_hir_id(opaque_local_def_id);
+                match &hir.expect_item(opaque_hir_id).kind {
+                    hir::ItemKind::OpaqueTy(opaque_hir_ty) => opaque_hir_ty,
+                    _ => bug!("The HirId comes from a `ty::Opaque`"),
+                }
+            } else {
+                return false;
             };
 
             let (trait_ref, assoc_substs) = proj_ty.trait_ref_and_own_substs(self);

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -350,18 +350,26 @@ pub trait PrettyPrinter<'tcx>:
             match self.tcx().extern_crate(def_id) {
                 Some(&ExternCrate { src, dependency_of, span, .. }) => match (src, dependency_of) {
                     (ExternCrateSource::Extern(def_id), LOCAL_CRATE) => {
-                        debug!("try_print_visible_def_path: def_id={:?}", def_id);
-                        return Ok((
-                            if !span.is_dummy() {
-                                self.print_def_path(def_id, &[])?
-                            } else {
-                                self.path_crate(cnum)?
-                            },
-                            true,
-                        ));
+                        // NOTE(eddyb) the only reason `span` might be dummy,
+                        // that we're aware of, is that it's the `std`/`core`
+                        // `extern crate` injected by default.
+                        // FIXME(eddyb) find something better to key this on,
+                        // or avoid ending up with `ExternCrateSource::Extern`,
+                        // for the injected `std`/`core`.
+                        if span.is_dummy() {
+                            return Ok((self.path_crate(cnum)?, true));
+                        }
+
+                        // Disable `try_print_trimmed_def_path` behavior within
+                        // the `print_def_path` call, to avoid infinite recursion
+                        // in cases where the `extern crate foo` has non-trivial
+                        // parents, e.g. it's nested in `impl foo::Trait for Bar`
+                        // (see also issues #55779 and #87932).
+                        self = with_no_visible_paths(|| self.print_def_path(def_id, &[]))?;
+
+                        return Ok((self, true));
                     }
                     (ExternCrateSource::Path, LOCAL_CRATE) => {
-                        debug!("try_print_visible_def_path: def_id={:?}", def_id);
                         return Ok((self.path_crate(cnum)?, true));
                     }
                     _ => {}

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1342,10 +1342,10 @@ impl<'a> Parser<'a> {
 
                 self.struct_span_err(
                     MultiSpan::from_spans(vec![begin_par_sp, self.prev_token.span]),
-                    "unexpected parenthesis surrounding `for` loop head",
+                    "unexpected parentheses surrounding `for` loop head",
                 )
                 .multipart_suggestion(
-                    "remove parenthesis in `for` loop",
+                    "remove parentheses in `for` loop",
                     vec![(begin_par_sp, String::new()), (self.prev_token.span, String::new())],
                     // With e.g. `for (x) in y)` this would replace `(x) in y)`
                     // with `x) in y)` which is syntactically invalid.

compiler/rustc_parse/src/parser/mod.rs

@@ -1258,7 +1258,7 @@ impl<'a> Parser<'a> {
     /// Parses `pub`, `pub(crate)` and `pub(in path)` plus shortcuts `crate` for `pub(crate)`,
     /// `pub(self)` for `pub(in self)` and `pub(super)` for `pub(in super)`.
     /// If the following element can't be a tuple (i.e., it's a function definition), then
-    /// it's not a tuple struct field), and the contents within the parentheses isn't valid,
+    /// it's not a tuple struct field), and the contents within the parentheses aren't valid,
     /// so emit a proper diagnostic.
     // Public for rustfmt usage.
     pub fn parse_visibility(&mut self, fbt: FollowedByType) -> PResult<'a, Visibility> {

compiler/rustc_parse/src/parser/stmt.rs

@@ -328,7 +328,7 @@ impl<'a> Parser<'a> {
                     ),
                 )
                 .multipart_suggestion(
-                    "wrap the expression in parenthesis",
+                    "wrap the expression in parentheses",
                     suggs,
                     Applicability::MachineApplicable,
                 )
@@ -349,7 +349,7 @@ impl<'a> Parser<'a> {
                 "right curly brace `}` before `else` in a `let...else` statement not allowed",
             )
             .multipart_suggestion(
-                "try wrapping the expression in parenthesis",
+                "try wrapping the expression in parentheses",
                 suggs,
                 Applicability::MachineApplicable,
             )