Auto merge of #122830 - matthiaskrgr:rollup-uk2by3f, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #122402 (Make `#[diagnostic::on_unimplemented]` format string parsing more robust)
 - #122644 (pattern analysis: add a custom test harness)
 - #122733 (Strip placeholders from hidden types before remapping generic parameter)
 - #122752 (Interpolated cleanups)
 - #122771 (add some comments to hir::ModuleItems)
 - #122793 (Implement macro-based deref!() syntax for deref patterns)
 - #122810 (Remove `target_override`)
 - #122827 (Remove unnecessary braces from `bug`/`span_bug`)

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

Author: bors

Cargo.lock

@@ -4440,6 +4440,8 @@ dependencies = [
  "rustc_target",
  "smallvec",
  "tracing",
+ "tracing-subscriber",
+ "tracing-tree",
 ]
 
 [[package]]

compiler/rustc_ast/src/ast.rs

@@ -621,7 +621,9 @@ impl Pat {
             | PatKind::Or(s) => s.iter().for_each(|p| p.walk(it)),
 
             // Trivial wrappers over inner patterns.
-            PatKind::Box(s) | PatKind::Ref(s, _) | PatKind::Paren(s) => s.walk(it),
+            PatKind::Box(s) | PatKind::Deref(s) | PatKind::Ref(s, _) | PatKind::Paren(s) => {
+                s.walk(it)
+            }
 
             // These patterns do not contain subpatterns, skip.
             PatKind::Wild
@@ -792,6 +794,9 @@ pub enum PatKind {
     /// A `box` pattern.
     Box(P<Pat>),
 
+    /// A `deref` pattern (currently `deref!()` macro-based syntax).
+    Deref(P<Pat>),
+
     /// A reference pattern (e.g., `&mut (a, b)`).
     Ref(P<Pat>, Mutability),
 

compiler/rustc_ast/src/mut_visit.rs

@@ -1295,6 +1295,7 @@ pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
             fields.flat_map_in_place(|field| vis.flat_map_pat_field(field));
         }
         PatKind::Box(inner) => vis.visit_pat(inner),
+        PatKind::Deref(inner) => vis.visit_pat(inner),
         PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
         PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
             visit_opt(e1, |e| vis.visit_expr(e));

compiler/rustc_ast/src/token.rs

@@ -105,7 +105,7 @@ impl Lit {
         }
     }
 
-    /// Keep this in sync with `Token::can_begin_literal_or_bool` excluding unary negation.
+    /// Keep this in sync with `Token::can_begin_literal_maybe_minus` excluding unary negation.
     pub fn from_token(token: &Token) -> Option<Lit> {
         match token.uninterpolate().kind {
             Ident(name, IdentIsRaw::No) if name.is_bool_lit() => Some(Lit::new(Bool, name, None)),
@@ -664,7 +664,7 @@ impl Token {
     }
 
     /// Returns `true` if the token is an interpolated path.
-    fn is_path(&self) -> bool {
+    fn is_whole_path(&self) -> bool {
         if let Interpolated(nt) = &self.kind
             && let NtPath(..) = &nt.0
         {
@@ -710,7 +710,7 @@ impl Token {
     pub fn is_path_start(&self) -> bool {
         self == &ModSep
             || self.is_qpath_start()
-            || self.is_path()
+            || self.is_whole_path()
             || self.is_path_segment_keyword()
             || self.is_ident() && !self.is_reserved_ident()
     }

compiler/rustc_ast/src/tokenstream.rs

@@ -28,18 +28,7 @@ use smallvec::{smallvec, SmallVec};
 use std::borrow::Cow;
 use std::{cmp, fmt, iter};
 
-/// When the main Rust parser encounters a syntax-extension invocation, it
-/// parses the arguments to the invocation as a token tree. This is a very
-/// loose structure, such that all sorts of different AST fragments can
-/// be passed to syntax extensions using a uniform type.
-///
-/// If the syntax extension is an MBE macro, it will attempt to match its
-/// LHS token tree against the provided token tree, and if it finds a
-/// match, will transcribe the RHS token tree, splicing in any captured
-/// `macro_parser::matched_nonterminals` into the `SubstNt`s it finds.
-///
-/// The RHS of an MBE macro is the only place `SubstNt`s are substituted.
-/// Nothing special happens to misnamed or misplaced `SubstNt`s.
+/// Part of a `TokenStream`.
 #[derive(Debug, Clone, PartialEq, Encodable, Decodable, HashStable_Generic)]
 pub enum TokenTree {
     /// A single token. Should never be `OpenDelim` or `CloseDelim`, because

compiler/rustc_ast/src/visit.rs

@@ -576,7 +576,10 @@ pub fn walk_pat<'a, V: Visitor<'a>>(visitor: &mut V, pattern: &'a Pat) -> V::Res
             try_visit!(visitor.visit_path(path, pattern.id));
             walk_list!(visitor, visit_pat_field, fields);
         }
-        PatKind::Box(subpattern) | PatKind::Ref(subpattern, _) | PatKind::Paren(subpattern) => {
+        PatKind::Box(subpattern)
+        | PatKind::Deref(subpattern)
+        | PatKind::Ref(subpattern, _)
+        | PatKind::Paren(subpattern) => {
             try_visit!(visitor.visit_pat(subpattern));
         }
         PatKind::Ident(_, ident, optional_subpattern) => {

compiler/rustc_ast_lowering/src/pat.rs

@@ -91,6 +91,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     PatKind::Box(inner) => {
                         break hir::PatKind::Box(self.lower_pat(inner));
                     }
+                    PatKind::Deref(inner) => {
+                        break hir::PatKind::Deref(self.lower_pat(inner));
+                    }
                     PatKind::Ref(inner, mutbl) => {
                         break hir::PatKind::Ref(self.lower_pat(inner), *mutbl);
                     }

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -413,10 +413,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
             PatKind::Box(..) => {
-                if !self.features.deref_patterns {
-                    // Allow box patterns under `deref_patterns`.
-                    gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
-                }
+                gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
             }
             PatKind::Range(_, Some(_), Spanned { node: RangeEnd::Excluded, .. }) => {
                 gate!(
@@ -610,10 +607,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
         };
     }
 
-    if !visitor.features.deref_patterns {
-        // Allow box patterns under `deref_patterns`.
-        gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
-    }
+    gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
     gate_all_legacy_dont_use!(trait_alias, "trait aliases are experimental");
     // Despite being a new feature, `where T: Trait<Assoc(): Sized>`, which is RTN syntax now,
     // used to be gated under associated_type_bounds, which are right above, so RTN needs to

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1626,6 +1626,12 @@ impl<'a> State<'a> {
                 self.word("box ");
                 self.print_pat(inner);
             }
+            PatKind::Deref(inner) => {
+                self.word("deref!");
+                self.popen();
+                self.print_pat(inner);
+                self.pclose();
+            }
             PatKind::Ref(inner, mutbl) => {
                 self.word("&");
                 if mutbl.is_mut() {

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -192,6 +192,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         .find(|ur_vid| self.eval_equal(vid, **ur_vid))
                         .and_then(|ur_vid| self.definitions[*ur_vid].external_name)
                         .unwrap_or(infcx.tcx.lifetimes.re_erased),
+                    ty::RePlaceholder(_) => ty::Region::new_error_with_message(
+                        infcx.tcx,
+                        concrete_type.span,
+                        "hidden type contains placeholders, we don't support higher kinded opaques yet",
+                    ),
                     _ => region,
                 });
             debug!(?universal_concrete_type);