Rollup merge of rust-lang#102286 - compiler-errors:recover-semi-in-block-item, r=davidtwco

Recover some items that expect braces and don't take semicolons Fixes rust-lang#102262

Author: matthiaskrgr

compiler/rustc_error_messages/locales/en-US/parser.ftl

@@ -158,3 +158,6 @@ parser_remove_let = expected pattern, found `let`
 
 parser_use_eq_instead = unexpected `==`
  .suggestion = try using `=` instead
+
+parser_use_empty_block_not_semi = expected { "`{}`" }, found `;`
+ .suggestion = try using { "`{}`" } instead

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -745,6 +745,14 @@ pub(crate) struct UseEqInstead {
  pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(parser::use_empty_block_not_semi)]
+pub(crate) struct UseEmptyBlockNotSemi {
+ #[primary_span]
+ #[suggestion_hidden(applicability = "machine-applicable", code = "{{}}")]
+ pub span: Span,
+}
+
 // SnapshotParser is used to create a snapshot of the parser
 // without causing duplicate errors being emitted when the `Parser`
 // is dropped.

compiler/rustc_parse/src/parser/item.rs

@@ -1,4 +1,4 @@
-use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error};
+use super::diagnostics::{dummy_arg, ConsumeClosingDelim, Error, UseEmptyBlockNotSemi};
 use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{AttrWrapper, FollowedByType, ForceCollect, Parser, PathStyle, TrailingToken};
 
@@ -664,6 +664,14 @@ impl<'a> Parser<'a> {
  mut parse_item: impl FnMut(&mut Parser<'a>) -> PResult<'a, Option<Option<T>>>,
  ) -> PResult<'a, Vec<T>> {
  let open_brace_span = self.token.span;
+
+ // Recover `impl Ty;` instead of `impl Ty {}`
+ if self.token == TokenKind::Semi {
+ self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+ self.bump();
+ return Ok(vec![]);
+ }
+
  self.expect(&token::OpenDelim(Delimiter::Brace))?;
  attrs.extend(self.parse_inner_attributes()?);
 
@@ -1305,12 +1313,19 @@ impl<'a> Parser<'a> {
  let mut generics = self.parse_generics()?;
  generics.where_clause = self.parse_where_clause()?;
 
- let (variants, _) = self
- .parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant())
- .map_err(|e| {
- self.recover_stmt();
- e
- })?;
+ // Possibly recover `enum Foo;` instead of `enum Foo {}`
+ let (variants, _) = if self.token == TokenKind::Semi {
+ self.sess.emit_err(UseEmptyBlockNotSemi { span: self.token.span });
+ self.bump();
+ (vec![], false)
+ } else {
+ self.parse_delim_comma_seq(Delimiter::Brace, |p| p.parse_enum_variant()).map_err(
+ |e| {
+ self.recover_stmt();
+ e
+ },
+ )?
+ };
 
  let enum_definition = EnumDef { variants: variants.into_iter().flatten().collect() };
  Ok((id, ItemKind::Enum(enum_definition, generics)))

src/test/ui/parser/empty-impl-semicolon.rs

@@ -1 +1,4 @@
-impl Foo; //~ ERROR expected one of `!`, `(`, `+`, `::`, `<`, `for`, `where`, or `{`, found `;`
+struct Foo;
+impl Foo; //~ ERROR expected `{}`, found `;`
+
+fn main() {}

src/test/ui/parser/empty-impl-semicolon.stderr

@@ -1,8 +1,10 @@
-error: expected one of `!`, `(`, `+`, `::`, `<`, `for`, `where`, or `{`, found `;`
- --> $DIR/empty-impl-semicolon.rs:1:9
+error: expected `{}`, found `;`
+ --> $DIR/empty-impl-semicolon.rs:2:9
  |
 LL | impl Foo;
- | ^ expected one of 8 possible tokens
+ | ^
+ |
+ = help: try using `{}` instead
 
 error: aborting due to previous error
 

src/test/ui/parser/item-needs-block.rs

@@ -0,0 +1,10 @@
+trait Trait;
+//~^ ERROR expected `{}`, found `;`
+
+impl Trait for ();
+//~^ ERROR expected `{}`, found `;`
+
+enum Enum;
+//~^ ERROR expected `{}`, found `;`
+
+fn main() {}

src/test/ui/parser/item-needs-block.stderr

@@ -0,0 +1,26 @@
+error: expected `{}`, found `;`
+ --> $DIR/item-needs-block.rs:1:12
+ |
+LL | trait Trait;
+ | ^
+ |
+ = help: try using `{}` instead
+
+error: expected `{}`, found `;`
+ --> $DIR/item-needs-block.rs:4:18
+ |
+LL | impl Trait for ();
+ | ^
+ |
+ = help: try using `{}` instead
+
+error: expected `{}`, found `;`
+ --> $DIR/item-needs-block.rs:7:10
+ |
+LL | enum Enum;
+ | ^
+ |
+ = help: try using `{}` instead
+
+error: aborting due to 3 previous errors
+