diff options
Diffstat (limited to 'compiler/rustc_parse/src/parser/item.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/item.rs | 148 |
1 files changed, 128 insertions, 20 deletions
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs index 1470180dea7..1301ed3e388 100644 --- a/compiler/rustc_parse/src/parser/item.rs +++ b/compiler/rustc_parse/src/parser/item.rs @@ -226,9 +226,9 @@ impl<'a> Parser<'a> { } else if self.is_static_global() { // STATIC ITEM self.bump(); // `static` - let m = self.parse_mutability(); - let (ident, ty, expr) = self.parse_item_global(Some(m))?; - (ident, ItemKind::Static(Box::new(StaticItem { ty, mutability: m, expr }))) + let mutability = self.parse_mutability(); + let (ident, item) = self.parse_static_item(mutability)?; + (ident, ItemKind::Static(Box::new(item))) } else if let Const::Yes(const_span) = self.parse_constness(Case::Sensitive) { // CONST ITEM if self.token.is_keyword(kw::Impl) { @@ -236,8 +236,16 @@ impl<'a> Parser<'a> { self.recover_const_impl(const_span, attrs, def_())? } else { self.recover_const_mut(const_span); - let (ident, ty, expr) = self.parse_item_global(None)?; - (ident, ItemKind::Const(Box::new(ConstItem { defaultness: def_(), ty, expr }))) + let (ident, generics, ty, expr) = self.parse_const_item()?; + ( + ident, + ItemKind::Const(Box::new(ConstItem { + defaultness: def_(), + generics, + ty, + expr, + })), + ) } } else if self.check_keyword(kw::Trait) || self.check_auto_or_unsafe_trait_item() { // TRAIT ITEM @@ -878,6 +886,7 @@ impl<'a> Parser<'a> { self.sess.emit_err(errors::AssociatedStaticItemNotAllowed { span }); AssocItemKind::Const(Box::new(ConstItem { defaultness: Defaultness::Final, + generics: Generics::default(), ty, expr, })) @@ -892,7 +901,7 @@ impl<'a> Parser<'a> { /// Parses a `type` alias with the following grammar: /// ```ebnf - /// TypeAlias = "type" Ident Generics {":" GenericBounds}? {"=" Ty}? ";" ; + /// TypeAlias = "type" Ident Generics (":" GenericBounds)? WhereClause ("=" Ty)? WhereClause ";" ; /// ``` /// The `"type"` has already been eaten. fn parse_type_alias(&mut self, defaultness: Defaultness) -> PResult<'a, ItemInfo> { @@ -1220,33 +1229,132 @@ impl<'a> Parser<'a> { Ok(impl_info) } - /// Parse `["const" | ("static" "mut"?)] $ident ":" $ty (= $expr)?` with - /// `["const" | ("static" "mut"?)]` already parsed and stored in `m`. + /// Parse a static item with the prefix `"static" "mut"?` already parsed and stored in `mutability`. /// - /// When `m` is `"const"`, `$ident` may also be `"_"`. - fn parse_item_global( - &mut self, - m: Option<Mutability>, - ) -> PResult<'a, (Ident, P<Ty>, Option<P<ast::Expr>>)> { - let id = if m.is_none() { self.parse_ident_or_underscore() } else { self.parse_ident() }?; + /// ```ebnf + /// Static = "static" "mut"? $ident ":" $ty (= $expr)? ";" ; + /// ``` + fn parse_static_item(&mut self, mutability: Mutability) -> PResult<'a, (Ident, StaticItem)> { + let ident = self.parse_ident()?; + + if self.token.kind == TokenKind::Lt && self.may_recover() { + let generics = self.parse_generics()?; + self.sess.emit_err(errors::StaticWithGenerics { span: generics.span }); + } - // Parse the type of a `const` or `static mut?` item. - // That is, the `":" $ty` fragment. + // Parse the type of a static item. That is, the `":" $ty` fragment. + // FIXME: This could maybe benefit from `.may_recover()`? let ty = match (self.eat(&token::Colon), self.check(&token::Eq) | self.check(&token::Semi)) { - // If there wasn't a `:` or the colon was followed by a `=` or `;` recover a missing type. (true, false) => self.parse_ty()?, - (colon, _) => self.recover_missing_const_type(colon, m), + // If there wasn't a `:` or the colon was followed by a `=` or `;`, recover a missing type. + (colon, _) => self.recover_missing_global_item_type(colon, Some(mutability)), + }; + + let expr = if self.eat(&token::Eq) { Some(self.parse_expr()?) } else { None }; + + self.expect_semi()?; + + Ok((ident, StaticItem { ty, mutability, expr })) + } + + /// Parse a constant item with the prefix `"const"` already parsed. + /// + /// ```ebnf + /// Const = "const" ($ident | "_") Generics ":" $ty (= $expr)? WhereClause ";" ; + /// ``` + fn parse_const_item(&mut self) -> PResult<'a, (Ident, Generics, P<Ty>, Option<P<ast::Expr>>)> { + let ident = self.parse_ident_or_underscore()?; + + let mut generics = self.parse_generics()?; + + // Check the span for emptiness instead of the list of parameters in order to correctly + // recognize and subsequently flag empty parameter lists (`<>`) as unstable. + if !generics.span.is_empty() { + self.sess.gated_spans.gate(sym::generic_const_items, generics.span); + } + + // Parse the type of a constant item. That is, the `":" $ty` fragment. + // FIXME: This could maybe benefit from `.may_recover()`? + let ty = match ( + self.eat(&token::Colon), + self.check(&token::Eq) | self.check(&token::Semi) | self.check_keyword(kw::Where), + ) { + (true, false) => self.parse_ty()?, + // If there wasn't a `:` or the colon was followed by a `=`, `;` or `where`, recover a missing type. + (colon, _) => self.recover_missing_global_item_type(colon, None), }; + // Proactively parse a where-clause to be able to provide a good error message in case we + // encounter the item body following it. + let before_where_clause = + if self.may_recover() { self.parse_where_clause()? } else { WhereClause::default() }; + let expr = if self.eat(&token::Eq) { Some(self.parse_expr()?) } else { None }; + + let after_where_clause = self.parse_where_clause()?; + + // Provide a nice error message if the user placed a where-clause before the item body. + // Users may be tempted to write such code if they are still used to the deprecated + // where-clause location on type aliases and associated types. See also #89122. + if before_where_clause.has_where_token && let Some(expr) = &expr { + self.sess.emit_err(errors::WhereClauseBeforeConstBody { + span: before_where_clause.span, + name: ident.span, + body: expr.span, + sugg: if !after_where_clause.has_where_token { + self.sess.source_map().span_to_snippet(expr.span).ok().map(|body| { + errors::WhereClauseBeforeConstBodySugg { + left: before_where_clause.span.shrink_to_lo(), + snippet: body, + right: before_where_clause.span.shrink_to_hi().to(expr.span), + } + }) + } else { + // FIXME(generic_const_items): Provide a structured suggestion to merge the first + // where-clause into the second one. + None + }, + }); + } + + // Merge the predicates of both where-clauses since either one can be relevant. + // If we didn't parse a body (which is valid for associated consts in traits) and we were + // allowed to recover, `before_where_clause` contains the predicates, otherwise they are + // in `after_where_clause`. Further, both of them might contain predicates iff two + // where-clauses were provided which is syntactically ill-formed but we want to recover from + // it and treat them as one large where-clause. + let mut predicates = before_where_clause.predicates; + predicates.extend(after_where_clause.predicates); + let where_clause = WhereClause { + has_where_token: before_where_clause.has_where_token + || after_where_clause.has_where_token, + predicates, + span: if after_where_clause.has_where_token { + after_where_clause.span + } else { + before_where_clause.span + }, + }; + + if where_clause.has_where_token { + self.sess.gated_spans.gate(sym::generic_const_items, where_clause.span); + } + + generics.where_clause = where_clause; + self.expect_semi()?; - Ok((id, ty, expr)) + + Ok((ident, generics, ty, expr)) } /// We were supposed to parse `":" $ty` but the `:` or the type was missing. /// This means that the type is missing. - fn recover_missing_const_type(&mut self, colon_present: bool, m: Option<Mutability>) -> P<Ty> { + fn recover_missing_global_item_type( + &mut self, + colon_present: bool, + m: Option<Mutability>, + ) -> P<Ty> { // Construct the error and stash it away with the hope // that typeck will later enrich the error with a type. let kind = match m { |