Revert "Teach parser to understand fake anonymous enum syntax" and related commits

Revert "review comment: Remove AST AnonTy"

This reverts commit 020cca8d36.

Revert "Ensure macros are not affected"

This reverts commit 12d18e4031.

Revert "Emit fewer errors on patterns with possible type ascription"

This reverts commit c847a01a3b.

Revert "Teach parser to understand fake anonymous enum syntax"

This reverts commit 2d82420665.

compiler/rustc_ast/src/visit.rs

@@ -403,8 +403,8 @@ pub fn walk_ty<'a, V: Visitor<'a>>(visitor: &mut V, typ: &'a Ty) {
             walk_list!(visitor, visit_lifetime, opt_lifetime, LifetimeCtxt::Ref);
             visitor.visit_ty(&mutable_type.ty)
         }
-        TyKind::Tup(tys) => {
+        TyKind::Tup(tuple_element_types) => {
-            walk_list!(visitor, visit_ty, tys);
+            walk_list!(visitor, visit_ty, tuple_element_types);
         }
         TyKind::BareFn(function_declaration) => {
             walk_list!(visitor, visit_generic_param, &function_declaration.generic_params);

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2394,7 +2394,7 @@ impl<'a> Parser<'a> {
 
     /// Some special error handling for the "top-level" patterns in a match arm,
     /// `for` loop, `let`, &c. (in contrast to subpatterns within such).
-    pub(crate) fn maybe_recover_colon_colon_in_pat_typo_or_anon_enum(
+    pub(crate) fn maybe_recover_colon_colon_in_pat_typo(
         &mut self,
         mut first_pat: P<Pat>,
         expected: Option<Expected>,
@@ -2405,41 +2405,26 @@ impl<'a> Parser<'a> {
         if !matches!(first_pat.kind, PatKind::Ident(_, _, None) | PatKind::Path(..))
             || !self.look_ahead(1, |token| token.is_ident() && !token.is_reserved_ident())
         {
-            let mut snapshot_type = self.create_snapshot_for_diagnostic();
-            snapshot_type.bump(); // `:`
-            match snapshot_type.parse_ty() {
-                Err(inner_err) => {
-                    inner_err.cancel();
-                }
-                Ok(ty) => {
-                    let Err(mut err) = self.expected_one_of_not_found(&[], &[]) else {
-                        return first_pat;
-                    };
-                    err.span_label(ty.span, "specifying the type of a pattern isn't supported");
-                    self.restore_snapshot(snapshot_type);
-                    let span = first_pat.span.to(ty.span);
-                    first_pat = self.mk_pat(span, PatKind::Wild);
-                    err.emit();
-                }
-            }
             return first_pat;
         }
         // The pattern looks like it might be a path with a `::` -> `:` typo:
         // `match foo { bar:baz => {} }`
-        let colon_span = self.token.span;
+        let span = self.token.span;
         // We only emit "unexpected `:`" error here if we can successfully parse the
         // whole pattern correctly in that case.
-        let mut snapshot_pat = self.create_snapshot_for_diagnostic();
+        let snapshot = self.create_snapshot_for_diagnostic();
-        let mut snapshot_type = self.create_snapshot_for_diagnostic();
 
         // Create error for "unexpected `:`".
         match self.expected_one_of_not_found(&[], &[]) {
             Err(mut err) => {
-                snapshot_pat.bump(); // Skip the `:`.
+                self.bump(); // Skip the `:`.
-                snapshot_type.bump(); // Skip the `:`.
+                match self.parse_pat_no_top_alt(expected) {
-                match snapshot_pat.parse_pat_no_top_alt(expected) {
                     Err(inner_err) => {
+                        // Carry on as if we had not done anything, callers will emit a
+                        // reasonable error.
                         inner_err.cancel();
+                        err.cancel();
+                        self.restore_snapshot(snapshot);
                     }
                     Ok(mut pat) => {
                         // We've parsed the rest of the pattern.
@@ -2503,8 +2488,8 @@ impl<'a> Parser<'a> {
                             _ => {}
                         }
                         if show_sugg {
-                            err.span_suggestion_verbose(
+                            err.span_suggestion(
-                                colon_span.until(self.look_ahead(1, |t| t.span)),
+                                span,
                                 "maybe write a path separator here",
                                 "::",
                                 Applicability::MaybeIncorrect,
@@ -2512,24 +2497,13 @@ impl<'a> Parser<'a> {
                         } else {
                             first_pat = self.mk_pat(new_span, PatKind::Wild);
                         }
-                        self.restore_snapshot(snapshot_pat);
+                        err.emit();
                     }
                 }
-                match snapshot_type.parse_ty() {
-                    Err(inner_err) => {
-                        inner_err.cancel();
-                    }
-                    Ok(ty) => {
-                        err.span_label(ty.span, "specifying the type of a pattern isn't supported");
-                        self.restore_snapshot(snapshot_type);
-                        let new_span = first_pat.span.to(ty.span);
-                        first_pat = self.mk_pat(new_span, PatKind::Wild);
-                    }
-                }
-                err.emit();
             }
             _ => {
                 // Carry on as if we had not done anything. This should be unreachable.
+                self.restore_snapshot(snapshot);
             }
         };
         first_pat

compiler/rustc_parse/src/parser/pat.rs

@@ -148,8 +148,7 @@ impl<'a> Parser<'a> {
 
             // Check if the user wrote `foo:bar` instead of `foo::bar`.
             if ra == RecoverColon::Yes {
-                first_pat =
+                first_pat = self.maybe_recover_colon_colon_in_pat_typo(first_pat, expected);
-                    self.maybe_recover_colon_colon_in_pat_typo_or_anon_enum(first_pat, expected);
             }
 
             if let Some(leading_vert_span) = leading_vert_span {

compiler/rustc_parse/src/parser/ty.rs

@@ -17,7 +17,6 @@ use rustc_ast::{
     self as ast, BareFnTy, FnRetTy, GenericBound, GenericBounds, GenericParam, Generics, Lifetime,
     MacCall, MutTy, Mutability, PolyTraitRef, TraitBoundModifier, TraitObjectSyntax, Ty, TyKind,
 };
-use rustc_ast_pretty::pprust;
 use rustc_errors::{Applicability, PResult};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::{kw, sym, Ident};
@@ -50,24 +49,17 @@ pub(super) enum AllowPlus {
     No,
 }
 
-#[derive(PartialEq, Clone, Copy)]
+#[derive(PartialEq)]
 pub(super) enum RecoverQPath {
     Yes,
     No,
 }
 
-#[derive(PartialEq, Clone, Copy)]
 pub(super) enum RecoverQuestionMark {
     Yes,
     No,
 }
 
-#[derive(PartialEq, Clone, Copy)]
-pub(super) enum RecoverAnonEnum {
-    Yes,
-    No,
-}
-
 /// Signals whether parsing a type should recover `->`.
 ///
 /// More specifically, when parsing a function like:
@@ -100,7 +92,7 @@ impl RecoverReturnSign {
 }
 
 // Is `...` (`CVarArgs`) legal at this level of type parsing?
-#[derive(PartialEq, Clone, Copy)]
+#[derive(PartialEq)]
 enum AllowCVariadic {
     Yes,
     No,
@@ -125,7 +117,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::Yes,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -140,7 +131,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             Some(ty_params),
             RecoverQuestionMark::Yes,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -155,7 +145,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::Yes,
-            RecoverAnonEnum::Yes,
         )
     }
 
@@ -173,7 +162,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::Yes,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -187,7 +175,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::No,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -199,7 +186,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::No,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -212,7 +198,6 @@ impl<'a> Parser<'a> {
             RecoverReturnSign::OnlyFatArrow,
             None,
             RecoverQuestionMark::Yes,
-            RecoverAnonEnum::No,
         )
     }
 
@@ -232,7 +217,6 @@ impl<'a> Parser<'a> {
                 recover_return_sign,
                 None,
                 RecoverQuestionMark::Yes,
-                RecoverAnonEnum::Yes,
             )?;
             FnRetTy::Ty(ty)
         } else if recover_return_sign.can_recover(&self.token.kind) {
@@ -247,7 +231,6 @@ impl<'a> Parser<'a> {
                 recover_return_sign,
                 None,
                 RecoverQuestionMark::Yes,
-                RecoverAnonEnum::Yes,
             )?;
             FnRetTy::Ty(ty)
         } else {
@@ -263,7 +246,6 @@ impl<'a> Parser<'a> {
         recover_return_sign: RecoverReturnSign,
         ty_generics: Option<&Generics>,
         recover_question_mark: RecoverQuestionMark,
-        recover_anon_enum: RecoverAnonEnum,
     ) -> PResult<'a, P<Ty>> {
         let allow_qpath_recovery = recover_qpath == RecoverQPath::Yes;
         maybe_recover_from_interpolated_ty_qpath!(self, allow_qpath_recovery);
@@ -347,50 +329,9 @@ impl<'a> Parser<'a> {
             AllowPlus::Yes => self.maybe_recover_from_bad_type_plus(&ty)?,
             AllowPlus::No => self.maybe_report_ambiguous_plus(impl_dyn_multi, &ty),
         }
-        if RecoverQuestionMark::Yes == recover_question_mark {
+        if let RecoverQuestionMark::Yes = recover_question_mark {
             ty = self.maybe_recover_from_question_mark(ty);
         }
-        if recover_anon_enum == RecoverAnonEnum::Yes
-            && self.check_noexpect(&token::BinOp(token::Or))
-            && self.look_ahead(1, |t| t.can_begin_type())
-        {
-            let mut pipes = vec![self.token.span];
-            let mut types = vec![ty];
-            loop {
-                if !self.eat(&token::BinOp(token::Or)) {
-                    break;
-                }
-                pipes.push(self.prev_token.span);
-                types.push(self.parse_ty_common(
-                    allow_plus,
-                    allow_c_variadic,
-                    recover_qpath,
-                    recover_return_sign,
-                    ty_generics,
-                    recover_question_mark,
-                    RecoverAnonEnum::No,
-                )?);
-            }
-            let mut err = self.struct_span_err(pipes, "anonymous enums are not supported");
-            for ty in &types {
-                err.span_label(ty.span, "");
-            }
-            err.help(&format!(
-                "create a named `enum` and use it here instead:\nenum Name {{\n{}\n}}",
-                types
-                    .iter()
-                    .enumerate()
-                    .map(|(i, t)| format!(
-                        "    Variant{}({}),",
-                        i + 1, // Lets not confuse people with zero-indexing :)
-                        pprust::to_string(|s| s.print_type(&t)),
-                    ))
-                    .collect::<Vec<_>>()
-                    .join("\n"),
-            ));
-            err.emit();
-            return Ok(self.mk_ty(lo.to(self.prev_token.span), TyKind::Err));
-        }
         if allow_qpath_recovery { self.maybe_recover_from_bad_qpath(ty) } else { Ok(ty) }
     }
 

tests/ui/parser/anon-enums.rs

@@ -1,17 +0,0 @@
-fn foo(x: bool | i32) -> i32 | f64 {
-//~^ ERROR anonymous enums are not supported
-//~| ERROR anonymous enums are not supported
-    match x {
-        x: i32 => x, //~ ERROR expected
-        true => 42.,
-        false => 0.333,
-    }
-}
-
-fn main() {
-    match foo(true) {
-        42: i32 => (), //~ ERROR expected
-        _: f64 => (), //~ ERROR expected
-        x: i32 => (), //~ ERROR expected
-    }
-}

tests/ui/parser/anon-enums.stderr

@@ -1,68 +0,0 @@
-error: anonymous enums are not supported
-  --> $DIR/anon-enums.rs:1:16
-   |
-LL | fn foo(x: bool | i32) -> i32 | f64 {
-   |           ---- ^ ---
-   |
-   = help: create a named `enum` and use it here instead:
-           enum Name {
-               Variant1(bool),
-               Variant2(i32),
-           }
-
-error: anonymous enums are not supported
-  --> $DIR/anon-enums.rs:1:30
-   |
-LL | fn foo(x: bool | i32) -> i32 | f64 {
-   |                          --- ^ ---
-   |
-   = help: create a named `enum` and use it here instead:
-           enum Name {
-               Variant1(i32),
-               Variant2(f64),
-           }
-
-error: expected one of `@` or `|`, found `:`
-  --> $DIR/anon-enums.rs:5:10
-   |
-LL |         x: i32 => x,
-   |          ^ --- specifying the type of a pattern isn't supported
-   |          |
-   |          expected one of `@` or `|`
-   |
-help: maybe write a path separator here
-   |
-LL |         x::i32 => x,
-   |          ~~
-
-error: expected one of `...`, `..=`, `..`, or `|`, found `:`
-  --> $DIR/anon-enums.rs:13:11
-   |
-LL |         42: i32 => (),
-   |           ^ --- specifying the type of a pattern isn't supported
-   |           |
-   |           expected one of `...`, `..=`, `..`, or `|`
-
-error: expected `|`, found `:`
-  --> $DIR/anon-enums.rs:14:10
-   |
-LL |         _: f64 => (),
-   |          ^ --- specifying the type of a pattern isn't supported
-   |          |
-   |          expected `|`
-
-error: expected one of `@` or `|`, found `:`
-  --> $DIR/anon-enums.rs:15:10
-   |
-LL |         x: i32 => (),
-   |          ^ --- specifying the type of a pattern isn't supported
-   |          |
-   |          expected one of `@` or `|`
-   |
-help: maybe write a path separator here
-   |
-LL |         x::i32 => (),
-   |          ~~
-
-error: aborting due to 6 previous errors
-

tests/ui/parser/fake-anon-enums-in-macros.rs

@@ -1,20 +0,0 @@
-// build-pass
-macro_rules! check_ty {
-    ($Z:ty) => { compile_error!("triggered"); };
-    ($X:ty | $Y:ty) => { $X };
-}
-
-macro_rules! check {
-    ($Z:ty) => { compile_error!("triggered"); };
-    ($X:ty | $Y:ty) => { };
-}
-
-check! { i32 | u8 }
-
-fn foo(x: check_ty! { i32 | u8 }) -> check_ty! { i32 | u8 } {
-    x
-}
-fn main() {
-    let x: check_ty! { i32 | u8 } = 42;
-    let _: check_ty! { i32 | u8 } = foo(x);
-}

tests/ui/parser/issues/issue-87086-colon-path-sep.rs

@@ -68,6 +68,7 @@ fn main() {
         Foo:Bar::Baz => {}
         //~^ ERROR: expected one of
         //~| HELP: maybe write a path separator here
+        //~| ERROR: failed to resolve: `Bar` is a variant, not a module
     }
     match myfoo {
         Foo::Bar => {}

tests/ui/parser/issues/issue-87086-colon-path-sep.stderr

@@ -2,118 +2,89 @@ error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:17:12
    |
 LL |         Foo:Bar => {}
-   |            ^--- specifying the type of a pattern isn't supported
+   |            ^
    |            |
    |            expected one of `@` or `|`
-   |
+   |            help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         Foo::Bar => {}
-   |            ~~
 
 error: expected one of `!`, `(`, `...`, `..=`, `..`, `::`, `{`, or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:23:17
    |
 LL |         qux::Foo:Bar => {}
-   |                 ^--- specifying the type of a pattern isn't supported
+   |                 ^
    |                 |
    |                 expected one of 8 possible tokens
-   |
+   |                 help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         qux::Foo::Bar => {}
-   |                 ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:29:12
    |
 LL |         qux:Foo::Baz => {}
-   |            ^-------- specifying the type of a pattern isn't supported
+   |            ^
    |            |
    |            expected one of `@` or `|`
-   |
+   |            help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         qux::Foo::Baz => {}
-   |            ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:35:12
    |
 LL |         qux: Foo::Baz if true => {}
-   |            ^ -------- specifying the type of a pattern isn't supported
+   |            ^
    |            |
    |            expected one of `@` or `|`
-   |
+   |            help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         qux::Foo::Baz if true => {}
-   |            ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:40:15
    |
 LL |     if let Foo:Bar = f() {
-   |               ^--- specifying the type of a pattern isn't supported
+   |               ^
    |               |
    |               expected one of `@` or `|`
-   |
+   |               help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |     if let Foo::Bar = f() {
-   |               ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:48:16
    |
 LL |         ref qux: Foo::Baz => {}
-   |                ^ -------- specifying the type of a pattern isn't supported
+   |                ^
    |                |
    |                expected one of `@` or `|`
-   |
+   |                help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         ref qux::Foo::Baz => {}
-   |                ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:57:16
    |
 LL |         mut qux: Foo::Baz => {}
-   |                ^ -------- specifying the type of a pattern isn't supported
+   |                ^
    |                |
    |                expected one of `@` or `|`
-   |
+   |                help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         mut qux::Foo::Baz => {}
-   |                ~~
 
 error: expected one of `@` or `|`, found `:`
   --> $DIR/issue-87086-colon-path-sep.rs:68:12
    |
 LL |         Foo:Bar::Baz => {}
-   |            ^-------- specifying the type of a pattern isn't supported
+   |            ^
    |            |
    |            expected one of `@` or `|`
-   |
+   |            help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         Foo::Bar::Baz => {}
-   |            ~~
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:74:12
+  --> $DIR/issue-87086-colon-path-sep.rs:75:12
    |
 LL |         Foo:Bar => {}
-   |            ^--- specifying the type of a pattern isn't supported
+   |            ^
    |            |
    |            expected one of `@` or `|`
-   |
+   |            help: maybe write a path separator here: `::`
-help: maybe write a path separator here
-   |
-LL |         Foo::Bar => {}
-   |            ~~
 
-error: aborting due to 9 previous errors
+error[E0433]: failed to resolve: `Bar` is a variant, not a module
+  --> $DIR/issue-87086-colon-path-sep.rs:68:13
+   |
+LL |         Foo:Bar::Baz => {}
+   |             ^^^ `Bar` is a variant, not a module
 
+error: aborting due to 10 previous errors
+
+For more information about this error, try `rustc --explain E0433`.