compiler/rustc_parse/src/parser/attr.rs - third_party/rust - Git at Google

 use crate::errors::{
     InvalidMetaItem, InvalidMetaItemSuggQuoteIdent, InvalidMetaItemUnquotedIdent,
     SuffixedLiteralInAttribute,
 };
 use crate::fluent_generated as fluent;
 use crate::maybe_whole;

 use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle};
 use rustc_ast as ast;
 use rustc_ast::attr;
 use rustc_ast::token::{self, Delimiter};
 use rustc_errors::{codes::*, Diag, PResult};
 use rustc_span::{sym, BytePos, Span};
 use thin_vec::ThinVec;
 use tracing::debug;

 // Public for rustfmt usage
 #[derive(Debug)]
 pub enum InnerAttrPolicy {
     Permitted,
     Forbidden(Option<InnerAttrForbiddenReason>),
 }

 #[derive(Clone, Copy, Debug)]
 pub enum InnerAttrForbiddenReason {
     InCodeBlock,
     AfterOuterDocComment { prev_doc_comment_span: Span },
     AfterOuterAttribute { prev_outer_attr_sp: Span },
 }

 enum OuterAttributeType {
     DocComment,
     DocBlockComment,
     Attribute,
 }

 impl<'a> Parser<'a> {
     /// Parses attributes that appear before an item.
     pub(super) fn parse_outer_attributes(&mut self) -> PResult<'a, AttrWrapper> {
         let mut outer_attrs = ast::AttrVec::new();
         let mut just_parsed_doc_comment = false;
         let start_pos = self.num_bump_calls;
         loop {
             let attr = if self.check(&token::Pound) {
                 let prev_outer_attr_sp = outer_attrs.last().map(|attr| attr.span);

                 let inner_error_reason = if just_parsed_doc_comment {
                     Some(InnerAttrForbiddenReason::AfterOuterDocComment {
                         prev_doc_comment_span: prev_outer_attr_sp.unwrap(),
                     })
                 } else {
                     prev_outer_attr_sp.map(|prev_outer_attr_sp| {
                         InnerAttrForbiddenReason::AfterOuterAttribute { prev_outer_attr_sp }
                     })
                 };
                 let inner_parse_policy = InnerAttrPolicy::Forbidden(inner_error_reason);
                 just_parsed_doc_comment = false;
                 Some(self.parse_attribute(inner_parse_policy)?)
             } else if let token::DocComment(comment_kind, attr_style, data) = self.token.kind {
                 if attr_style != ast::AttrStyle::Outer {
                     let span = self.token.span;
                     let mut err = self
                         .dcx()
                         .struct_span_err(span, fluent::parse_inner_doc_comment_not_permitted);
                     err.code(E0753);
                     if let Some(replacement_span) = self.annotate_following_item_if_applicable(
                         &mut err,
                         span,
                         match comment_kind {
                             token::CommentKind::Line => OuterAttributeType::DocComment,
                             token::CommentKind::Block => OuterAttributeType::DocBlockComment,
                         },
                     ) {
                         err.note(fluent::parse_note);
                         err.span_suggestion_verbose(
                             replacement_span,
                             fluent::parse_suggestion,
                             "",
                             rustc_errors::Applicability::MachineApplicable,
                         );
                     }
                     err.emit();
                 }
                 self.bump();
                 just_parsed_doc_comment = true;
                 // Always make an outer attribute - this allows us to recover from a misplaced
                 // inner attribute.
                 Some(attr::mk_doc_comment(
                     &self.psess.attr_id_generator,
                     comment_kind,
                     ast::AttrStyle::Outer,
                     data,
                     self.prev_token.span,
                 ))
             } else {
                 None
             };

             if let Some(attr) = attr {
                 if attr.style == ast::AttrStyle::Outer {
                     outer_attrs.push(attr);
                 }
             } else {
                 break;
             }
         }
         Ok(AttrWrapper::new(outer_attrs, start_pos))
     }

     /// Matches `attribute = # ! [ meta_item ]`.
     /// `inner_parse_policy` prescribes how to handle inner attributes.
     // Public for rustfmt usage.
     pub fn parse_attribute(
         &mut self,
         inner_parse_policy: InnerAttrPolicy,
     ) -> PResult<'a, ast::Attribute> {
         debug!(
             "parse_attribute: inner_parse_policy={:?} self.token={:?}",
             inner_parse_policy, self.token
         );
         let lo = self.token.span;
         // Attributes can't have attributes of their own [Editor's note: not with that attitude]
         self.collect_tokens_no_attrs(|this| {
             assert!(this.eat(&token::Pound), "parse_attribute called in non-attribute position");

             let style =
                 if this.eat(&token::Not) { ast::AttrStyle::Inner } else { ast::AttrStyle::Outer };

             this.expect(&token::OpenDelim(Delimiter::Bracket))?;
             let item = this.parse_attr_item(false)?;
             this.expect(&token::CloseDelim(Delimiter::Bracket))?;
             let attr_sp = lo.to(this.prev_token.span);

             // Emit error if inner attribute is encountered and forbidden.
             if style == ast::AttrStyle::Inner {
                 this.error_on_forbidden_inner_attr(attr_sp, inner_parse_policy);
             }

             Ok(attr::mk_attr_from_item(&self.psess.attr_id_generator, item, None, style, attr_sp))
         })
     }

     fn annotate_following_item_if_applicable(
         &self,
         err: &mut Diag<'_>,
         span: Span,
         attr_type: OuterAttributeType,
     ) -> Option<Span> {
         let mut snapshot = self.create_snapshot_for_diagnostic();
         let lo = span.lo()
             + BytePos(match attr_type {
                 OuterAttributeType::Attribute => 1,
                 _ => 2,
             });
         let hi = lo + BytePos(1);
         let replacement_span = span.with_lo(lo).with_hi(hi);
         if let OuterAttributeType::DocBlockComment | OuterAttributeType::DocComment = attr_type {
             snapshot.bump();
         }
         loop {
             // skip any other attributes, we want the item
             if snapshot.token.kind == token::Pound {
                 if let Err(err) = snapshot.parse_attribute(InnerAttrPolicy::Permitted) {
                     err.cancel();
                     return Some(replacement_span);
                 }
             } else {
                 break;
             }
         }
         match snapshot.parse_item_common(
             AttrWrapper::empty(),
             true,
             false,
             FnParseMode { req_name: |_| true, req_body: true },
             ForceCollect::No,
         ) {
             Ok(Some(item)) => {
                 // FIXME(#100717)
                 err.arg("item", item.kind.descr());
                 err.span_label(item.span, fluent::parse_label_does_not_annotate_this);
                 err.span_suggestion_verbose(
                     replacement_span,
                     fluent::parse_sugg_change_inner_to_outer,
                     match attr_type {
                         OuterAttributeType::Attribute => "",
                         OuterAttributeType::DocBlockComment => "*",
                         OuterAttributeType::DocComment => "/",
                     },
                     rustc_errors::Applicability::MachineApplicable,
                 );
                 return None;
             }
             Err(item_err) => {
                 item_err.cancel();
             }
             Ok(None) => {}
         }
         Some(replacement_span)
     }

     pub(super) fn error_on_forbidden_inner_attr(&self, attr_sp: Span, policy: InnerAttrPolicy) {
         if let InnerAttrPolicy::Forbidden(reason) = policy {
             let mut diag = match reason.as_ref().copied() {
                 Some(InnerAttrForbiddenReason::AfterOuterDocComment { prev_doc_comment_span }) => {
                     self.dcx()
                         .struct_span_err(
                             attr_sp,
                             fluent::parse_inner_attr_not_permitted_after_outer_doc_comment,
                         )
                         .with_span_label(attr_sp, fluent::parse_label_attr)
                         .with_span_label(
                             prev_doc_comment_span,
                             fluent::parse_label_prev_doc_comment,
                         )
                 }
                 Some(InnerAttrForbiddenReason::AfterOuterAttribute { prev_outer_attr_sp }) => self
                     .dcx()
                     .struct_span_err(
                         attr_sp,
                         fluent::parse_inner_attr_not_permitted_after_outer_attr,
                     )
                     .with_span_label(attr_sp, fluent::parse_label_attr)
                     .with_span_label(prev_outer_attr_sp, fluent::parse_label_prev_attr),
                 Some(InnerAttrForbiddenReason::InCodeBlock) | None => {
                     self.dcx().struct_span_err(attr_sp, fluent::parse_inner_attr_not_permitted)
                 }
             };

             diag.note(fluent::parse_inner_attr_explanation);
             if self
                 .annotate_following_item_if_applicable(
                     &mut diag,
                     attr_sp,
                     OuterAttributeType::Attribute,
                 )
                 .is_some()
             {
                 diag.note(fluent::parse_outer_attr_explanation);
             };
             diag.emit();
         }
     }

     /// Parses an inner part of an attribute (the path and following tokens).
     /// The tokens must be either a delimited token stream, or empty token stream,
     /// or the "legacy" key-value form.
     ///     PATH `(` TOKEN_STREAM `)`
     ///     PATH `[` TOKEN_STREAM `]`
     ///     PATH `{` TOKEN_STREAM `}`
     ///     PATH
     ///     PATH `=` UNSUFFIXED_LIT
     /// The delimiters or `=` are still put into the resulting token stream.
     pub fn parse_attr_item(&mut self, capture_tokens: bool) -> PResult<'a, ast::AttrItem> {
         maybe_whole!(self, NtMeta, |attr| attr.into_inner());

         let do_parse = |this: &mut Self| {
             let path = this.parse_path(PathStyle::Mod)?;
             let args = this.parse_attr_args()?;
             Ok(ast::AttrItem { path, args, tokens: None })
         };
         // Attr items don't have attributes
         if capture_tokens { self.collect_tokens_no_attrs(do_parse) } else { do_parse(self) }
     }

     /// Parses attributes that appear after the opening of an item. These should
     /// be preceded by an exclamation mark, but we accept and warn about one
     /// terminated by a semicolon.
     ///
     /// Matches `inner_attrs*`.
     pub(crate) fn parse_inner_attributes(&mut self) -> PResult<'a, ast::AttrVec> {
         let mut attrs = ast::AttrVec::new();
         loop {
             let start_pos: u32 = self.num_bump_calls.try_into().unwrap();
             // Only try to parse if it is an inner attribute (has `!`).
             let attr = if self.check(&token::Pound) && self.look_ahead(1, |t| t == &token::Not) {
                 Some(self.parse_attribute(InnerAttrPolicy::Permitted)?)
             } else if let token::DocComment(comment_kind, attr_style, data) = self.token.kind {
                 if attr_style == ast::AttrStyle::Inner {
                     self.bump();
                     Some(attr::mk_doc_comment(
                         &self.psess.attr_id_generator,
                         comment_kind,
                         attr_style,
                         data,
                         self.prev_token.span,
                     ))
                 } else {
                     None
                 }
             } else {
                 None
             };
             if let Some(attr) = attr {
                 let end_pos: u32 = self.num_bump_calls.try_into().unwrap();
                 // If we are currently capturing tokens, mark the location of this inner attribute.
                 // If capturing ends up creating a `LazyAttrTokenStream`, we will include
                 // this replace range with it, removing the inner attribute from the final
                 // `AttrTokenStream`. Inner attributes are stored in the parsed AST note.
                 // During macro expansion, they are selectively inserted back into the
                 // token stream (the first inner attribute is removed each time we invoke the
                 // corresponding macro).
                 let range = start_pos..end_pos;
                 if let Capturing::Yes = self.capture_state.capturing {
                     self.capture_state.inner_attr_ranges.insert(attr.id, (range, vec![]));
                 }
                 attrs.push(attr);
             } else {
                 break;
             }
         }
         Ok(attrs)
     }

     // Note: must be unsuffixed.
     pub(crate) fn parse_unsuffixed_meta_item_lit(&mut self) -> PResult<'a, ast::MetaItemLit> {
         let lit = self.parse_meta_item_lit()?;
         debug!("checking if {:?} is unsuffixed", lit);

         if !lit.kind.is_unsuffixed() {
             self.dcx().emit_err(SuffixedLiteralInAttribute { span: lit.span });
         }

         Ok(lit)
     }

     /// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
     pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
         let cfg_predicate = self.parse_meta_item()?;
         self.expect(&token::Comma)?;

         // Presumably, the majority of the time there will only be one attr.
         let mut expanded_attrs = Vec::with_capacity(1);
         while self.token.kind != token::Eof {
             let lo = self.token.span;
             let item = self.parse_attr_item(true)?;
             expanded_attrs.push((item, lo.to(self.prev_token.span)));
             if !self.eat(&token::Comma) {
                 break;
             }
         }

         Ok((cfg_predicate, expanded_attrs))
     }

     /// Matches `COMMASEP(meta_item_inner)`.
     pub(crate) fn parse_meta_seq_top(&mut self) -> PResult<'a, ThinVec<ast::NestedMetaItem>> {
         // Presumably, the majority of the time there will only be one attr.
         let mut nmis = ThinVec::with_capacity(1);
         while self.token.kind != token::Eof {
             nmis.push(self.parse_meta_item_inner()?);
             if !self.eat(&token::Comma) {
                 break;
             }
         }
         Ok(nmis)
     }

     /// Matches the following grammar (per RFC 1559).
     /// ```ebnf
     /// meta_item : PATH ( '=' UNSUFFIXED_LIT | '(' meta_item_inner? ')' )? ;
     /// meta_item_inner : (meta_item | UNSUFFIXED_LIT) (',' meta_item_inner)? ;
     /// ```
     pub fn parse_meta_item(&mut self) -> PResult<'a, ast::MetaItem> {
         // We can't use `maybe_whole` here because it would bump in the `None`
         // case, which we don't want.
         if let token::Interpolated(nt) = &self.token.kind
             && let token::NtMeta(attr_item) = &nt.0
         {
             match attr_item.meta(attr_item.path.span) {
                 Some(meta) => {
                     self.bump();
                     return Ok(meta);
                 }
                 None => self.unexpected()?,
             }
         }

         let lo = self.token.span;
         let path = self.parse_path(PathStyle::Mod)?;
         let kind = self.parse_meta_item_kind()?;
         let span = lo.to(self.prev_token.span);
         Ok(ast::MetaItem { path, kind, span })
     }

     pub(crate) fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
         Ok(if self.eat(&token::Eq) {
             ast::MetaItemKind::NameValue(self.parse_unsuffixed_meta_item_lit()?)
         } else if self.check(&token::OpenDelim(Delimiter::Parenthesis)) {
             // Matches `meta_seq = ( COMMASEP(meta_item_inner) )`.
             let (list, _) = self.parse_paren_comma_seq(|p| p.parse_meta_item_inner())?;
             ast::MetaItemKind::List(list)
         } else {
             ast::MetaItemKind::Word
         })
     }

     /// Matches `meta_item_inner : (meta_item | UNSUFFIXED_LIT) ;`.
     fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
         match self.parse_unsuffixed_meta_item_lit() {
             Ok(lit) => return Ok(ast::NestedMetaItem::Lit(lit)),
             Err(err) => err.cancel(),
         }

         match self.parse_meta_item() {
             Ok(mi) => return Ok(ast::NestedMetaItem::MetaItem(mi)),
             Err(err) => err.cancel(),
         }

         let token = self.token.clone();

         // Check for unquoted idents in meta items, e.g.: #[cfg(key = foo)]
         // `from_expansion()` ensures we don't suggest for cases such as
         // `#[cfg(feature = $expr)]` in macros
         if self.prev_token == token::Eq && !self.token.span.from_expansion() {
             let before = self.token.span.shrink_to_lo();
             while matches!(self.token.kind, token::Ident(..)) {
                 self.bump();
             }
             let after = self.prev_token.span.shrink_to_hi();
             let sugg = InvalidMetaItemSuggQuoteIdent { before, after };
             return Err(self.dcx().create_err(InvalidMetaItemUnquotedIdent {
                 span: token.span,
                 token,
                 sugg,
             }));
         }

         Err(self.dcx().create_err(InvalidMetaItem { span: token.span, token }))
     }
 }

 /// The attributes are complete if all attributes are either a doc comment or a builtin attribute other than `cfg_attr`
 pub fn is_complete(attrs: &[ast::Attribute]) -> bool {
     attrs.iter().all(|attr| {
         attr.is_doc_comment()
             || attr.ident().is_some_and(|ident| {
                 ident.name != sym::cfg_attr && rustc_feature::is_builtin_attr_name(ident.name)
             })
     })
 }
	use crate::errors::{
	InvalidMetaItem, InvalidMetaItemSuggQuoteIdent, InvalidMetaItemUnquotedIdent,
	SuffixedLiteralInAttribute,
	};
	use crate::fluent_generated as fluent;
	use crate::maybe_whole;

	use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle};
	use rustc_ast as ast;
	use rustc_ast::attr;
	use rustc_ast::token::{self, Delimiter};
	use rustc_errors::{codes::*, Diag, PResult};
	use rustc_span::{sym, BytePos, Span};
	use thin_vec::ThinVec;
	use tracing::debug;

	// Public for rustfmt usage
	#[derive(Debug)]
	pub enum InnerAttrPolicy {
	Permitted,
	Forbidden(Option<InnerAttrForbiddenReason>),
	}

	#[derive(Clone, Copy, Debug)]
	pub enum InnerAttrForbiddenReason {
	InCodeBlock,
	AfterOuterDocComment { prev_doc_comment_span: Span },
	AfterOuterAttribute { prev_outer_attr_sp: Span },
	}

	enum OuterAttributeType {
	DocComment,
	DocBlockComment,
	Attribute,
	}

	impl<'a> Parser<'a> {
	/// Parses attributes that appear before an item.
	pub(super) fn parse_outer_attributes(&mut self) -> PResult<'a, AttrWrapper> {
	let mut outer_attrs = ast::AttrVec::new();
	let mut just_parsed_doc_comment = false;
	let start_pos = self.num_bump_calls;
	loop {
	let attr = if self.check(&token::Pound) {
	let prev_outer_attr_sp = outer_attrs.last().map(\|attr\| attr.span);

	let inner_error_reason = if just_parsed_doc_comment {
	Some(InnerAttrForbiddenReason::AfterOuterDocComment {
	prev_doc_comment_span: prev_outer_attr_sp.unwrap(),
	})
	} else {
	prev_outer_attr_sp.map(\|prev_outer_attr_sp\| {
	InnerAttrForbiddenReason::AfterOuterAttribute { prev_outer_attr_sp }
	})
	};
	let inner_parse_policy = InnerAttrPolicy::Forbidden(inner_error_reason);
	just_parsed_doc_comment = false;
	Some(self.parse_attribute(inner_parse_policy)?)
	} else if let token::DocComment(comment_kind, attr_style, data) = self.token.kind {
	if attr_style != ast::AttrStyle::Outer {
	let span = self.token.span;
	let mut err = self
	.dcx()
	.struct_span_err(span, fluent::parse_inner_doc_comment_not_permitted);
	err.code(E0753);
	if let Some(replacement_span) = self.annotate_following_item_if_applicable(
	&mut err,
	span,
	match comment_kind {
	token::CommentKind::Line => OuterAttributeType::DocComment,
	token::CommentKind::Block => OuterAttributeType::DocBlockComment,
	},
	) {
	err.note(fluent::parse_note);
	err.span_suggestion_verbose(
	replacement_span,
	fluent::parse_suggestion,
	"",
	rustc_errors::Applicability::MachineApplicable,
	);
	}
	err.emit();
	}
	self.bump();
	just_parsed_doc_comment = true;
	// Always make an outer attribute - this allows us to recover from a misplaced
	// inner attribute.
	Some(attr::mk_doc_comment(
	&self.psess.attr_id_generator,
	comment_kind,
	ast::AttrStyle::Outer,
	data,
	self.prev_token.span,
	))
	} else {
	None
	};

	if let Some(attr) = attr {
	if attr.style == ast::AttrStyle::Outer {
	outer_attrs.push(attr);
	}
	} else {
	break;
	}
	}
	Ok(AttrWrapper::new(outer_attrs, start_pos))
	}

	/// Matches `attribute = # ! [ meta_item ]`.
	/// `inner_parse_policy` prescribes how to handle inner attributes.
	// Public for rustfmt usage.
	pub fn parse_attribute(
	&mut self,
	inner_parse_policy: InnerAttrPolicy,
	) -> PResult<'a, ast::Attribute> {
	debug!(
	"parse_attribute: inner_parse_policy={:?} self.token={:?}",
	inner_parse_policy, self.token
	);
	let lo = self.token.span;
	// Attributes can't have attributes of their own [Editor's note: not with that attitude]
	self.collect_tokens_no_attrs(\|this\| {
	assert!(this.eat(&token::Pound), "parse_attribute called in non-attribute position");

	let style =
	if this.eat(&token::Not) { ast::AttrStyle::Inner } else { ast::AttrStyle::Outer };

	this.expect(&token::OpenDelim(Delimiter::Bracket))?;
	let item = this.parse_attr_item(false)?;
	this.expect(&token::CloseDelim(Delimiter::Bracket))?;
	let attr_sp = lo.to(this.prev_token.span);

	// Emit error if inner attribute is encountered and forbidden.
	if style == ast::AttrStyle::Inner {
	this.error_on_forbidden_inner_attr(attr_sp, inner_parse_policy);
	}

	Ok(attr::mk_attr_from_item(&self.psess.attr_id_generator, item, None, style, attr_sp))
	})
	}

	fn annotate_following_item_if_applicable(
	&self,
	err: &mut Diag<'_>,
	span: Span,
	attr_type: OuterAttributeType,
	) -> Option<Span> {
	let mut snapshot = self.create_snapshot_for_diagnostic();
	let lo = span.lo()
	+ BytePos(match attr_type {
	OuterAttributeType::Attribute => 1,
	_ => 2,
	});
	let hi = lo + BytePos(1);
	let replacement_span = span.with_lo(lo).with_hi(hi);
	if let OuterAttributeType::DocBlockComment \| OuterAttributeType::DocComment = attr_type {
	snapshot.bump();
	}
	loop {
	// skip any other attributes, we want the item
	if snapshot.token.kind == token::Pound {
	if let Err(err) = snapshot.parse_attribute(InnerAttrPolicy::Permitted) {
	err.cancel();
	return Some(replacement_span);
	}
	} else {
	break;
	}
	}
	match snapshot.parse_item_common(
	AttrWrapper::empty(),
	true,
	false,
	FnParseMode { req_name: \|_\| true, req_body: true },
	ForceCollect::No,
	) {
	Ok(Some(item)) => {
	// FIXME(#100717)
	err.arg("item", item.kind.descr());
	err.span_label(item.span, fluent::parse_label_does_not_annotate_this);
	err.span_suggestion_verbose(
	replacement_span,
	fluent::parse_sugg_change_inner_to_outer,
	match attr_type {
	OuterAttributeType::Attribute => "",
	OuterAttributeType::DocBlockComment => "*",
	OuterAttributeType::DocComment => "/",
	},
	rustc_errors::Applicability::MachineApplicable,
	);
	return None;
	}
	Err(item_err) => {
	item_err.cancel();
	}
	Ok(None) => {}
	}
	Some(replacement_span)
	}

	pub(super) fn error_on_forbidden_inner_attr(&self, attr_sp: Span, policy: InnerAttrPolicy) {
	if let InnerAttrPolicy::Forbidden(reason) = policy {
	let mut diag = match reason.as_ref().copied() {
	Some(InnerAttrForbiddenReason::AfterOuterDocComment { prev_doc_comment_span }) => {
	self.dcx()
	.struct_span_err(
	attr_sp,
	fluent::parse_inner_attr_not_permitted_after_outer_doc_comment,
	)
	.with_span_label(attr_sp, fluent::parse_label_attr)
	.with_span_label(
	prev_doc_comment_span,
	fluent::parse_label_prev_doc_comment,
	)
	}
	Some(InnerAttrForbiddenReason::AfterOuterAttribute { prev_outer_attr_sp }) => self
	.dcx()
	.struct_span_err(
	attr_sp,
	fluent::parse_inner_attr_not_permitted_after_outer_attr,
	)
	.with_span_label(attr_sp, fluent::parse_label_attr)
	.with_span_label(prev_outer_attr_sp, fluent::parse_label_prev_attr),
	Some(InnerAttrForbiddenReason::InCodeBlock) \| None => {
	self.dcx().struct_span_err(attr_sp, fluent::parse_inner_attr_not_permitted)
	}
	};

	diag.note(fluent::parse_inner_attr_explanation);
	if self
	.annotate_following_item_if_applicable(
	&mut diag,
	attr_sp,
	OuterAttributeType::Attribute,
	)
	.is_some()
	{
	diag.note(fluent::parse_outer_attr_explanation);
	};
	diag.emit();
	}
	}

	/// Parses an inner part of an attribute (the path and following tokens).
	/// The tokens must be either a delimited token stream, or empty token stream,
	/// or the "legacy" key-value form.
	/// PATH `(` TOKEN_STREAM `)`
	/// PATH `[` TOKEN_STREAM `]`
	/// PATH `{` TOKEN_STREAM `}`
	/// PATH
	/// PATH `=` UNSUFFIXED_LIT
	/// The delimiters or `=` are still put into the resulting token stream.
	pub fn parse_attr_item(&mut self, capture_tokens: bool) -> PResult<'a, ast::AttrItem> {
	maybe_whole!(self, NtMeta, \|attr\| attr.into_inner());

	let do_parse = \|this: &mut Self\| {
	let path = this.parse_path(PathStyle::Mod)?;
	let args = this.parse_attr_args()?;
	Ok(ast::AttrItem { path, args, tokens: None })
	};
	// Attr items don't have attributes
	if capture_tokens { self.collect_tokens_no_attrs(do_parse) } else { do_parse(self) }
	}

	/// Parses attributes that appear after the opening of an item. These should
	/// be preceded by an exclamation mark, but we accept and warn about one
	/// terminated by a semicolon.
	///
	/// Matches `inner_attrs*`.
	pub(crate) fn parse_inner_attributes(&mut self) -> PResult<'a, ast::AttrVec> {
	let mut attrs = ast::AttrVec::new();
	loop {
	let start_pos: u32 = self.num_bump_calls.try_into().unwrap();
	// Only try to parse if it is an inner attribute (has `!`).
	let attr = if self.check(&token::Pound) && self.look_ahead(1, \|t\| t == &token::Not) {
	Some(self.parse_attribute(InnerAttrPolicy::Permitted)?)
	} else if let token::DocComment(comment_kind, attr_style, data) = self.token.kind {
	if attr_style == ast::AttrStyle::Inner {
	self.bump();
	Some(attr::mk_doc_comment(
	&self.psess.attr_id_generator,
	comment_kind,
	attr_style,
	data,
	self.prev_token.span,
	))
	} else {
	None
	}
	} else {
	None
	};
	if let Some(attr) = attr {
	let end_pos: u32 = self.num_bump_calls.try_into().unwrap();
	// If we are currently capturing tokens, mark the location of this inner attribute.
	// If capturing ends up creating a `LazyAttrTokenStream`, we will include
	// this replace range with it, removing the inner attribute from the final
	// `AttrTokenStream`. Inner attributes are stored in the parsed AST note.
	// During macro expansion, they are selectively inserted back into the
	// token stream (the first inner attribute is removed each time we invoke the
	// corresponding macro).
	let range = start_pos..end_pos;
	if let Capturing::Yes = self.capture_state.capturing {
	self.capture_state.inner_attr_ranges.insert(attr.id, (range, vec![]));
	}
	attrs.push(attr);
	} else {
	break;
	}
	}
	Ok(attrs)
	}

	// Note: must be unsuffixed.
	pub(crate) fn parse_unsuffixed_meta_item_lit(&mut self) -> PResult<'a, ast::MetaItemLit> {
	let lit = self.parse_meta_item_lit()?;
	debug!("checking if {:?} is unsuffixed", lit);

	if !lit.kind.is_unsuffixed() {
	self.dcx().emit_err(SuffixedLiteralInAttribute { span: lit.span });
	}

	Ok(lit)
	}

	/// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
	pub fn parse_cfg_attr(&mut self) -> PResult<'a, (ast::MetaItem, Vec<(ast::AttrItem, Span)>)> {
	let cfg_predicate = self.parse_meta_item()?;
	self.expect(&token::Comma)?;

	// Presumably, the majority of the time there will only be one attr.
	let mut expanded_attrs = Vec::with_capacity(1);
	while self.token.kind != token::Eof {
	let lo = self.token.span;
	let item = self.parse_attr_item(true)?;
	expanded_attrs.push((item, lo.to(self.prev_token.span)));
	if !self.eat(&token::Comma) {
	break;
	}
	}

	Ok((cfg_predicate, expanded_attrs))
	}

	/// Matches `COMMASEP(meta_item_inner)`.
	pub(crate) fn parse_meta_seq_top(&mut self) -> PResult<'a, ThinVec<ast::NestedMetaItem>> {
	// Presumably, the majority of the time there will only be one attr.
	let mut nmis = ThinVec::with_capacity(1);
	while self.token.kind != token::Eof {
	nmis.push(self.parse_meta_item_inner()?);
	if !self.eat(&token::Comma) {
	break;
	}
	}
	Ok(nmis)
	}

	/// Matches the following grammar (per RFC 1559).
	/// ```ebnf
	/// meta_item : PATH ( '=' UNSUFFIXED_LIT \| '(' meta_item_inner? ')' )? ;
	/// meta_item_inner : (meta_item \| UNSUFFIXED_LIT) (',' meta_item_inner)? ;
	/// ```
	pub fn parse_meta_item(&mut self) -> PResult<'a, ast::MetaItem> {
	// We can't use `maybe_whole` here because it would bump in the `None`
	// case, which we don't want.
	if let token::Interpolated(nt) = &self.token.kind
	&& let token::NtMeta(attr_item) = &nt.0
	{
	match attr_item.meta(attr_item.path.span) {
	Some(meta) => {
	self.bump();
	return Ok(meta);
	}
	None => self.unexpected()?,
	}
	}

	let lo = self.token.span;
	let path = self.parse_path(PathStyle::Mod)?;
	let kind = self.parse_meta_item_kind()?;
	let span = lo.to(self.prev_token.span);
	Ok(ast::MetaItem { path, kind, span })
	}

	pub(crate) fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
	Ok(if self.eat(&token::Eq) {
	ast::MetaItemKind::NameValue(self.parse_unsuffixed_meta_item_lit()?)
	} else if self.check(&token::OpenDelim(Delimiter::Parenthesis)) {
	// Matches `meta_seq = ( COMMASEP(meta_item_inner) )`.
	let (list, _) = self.parse_paren_comma_seq(\|p\| p.parse_meta_item_inner())?;
	ast::MetaItemKind::List(list)
	} else {
	ast::MetaItemKind::Word
	})
	}

	/// Matches `meta_item_inner : (meta_item \| UNSUFFIXED_LIT) ;`.
	fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
	match self.parse_unsuffixed_meta_item_lit() {
	Ok(lit) => return Ok(ast::NestedMetaItem::Lit(lit)),
	Err(err) => err.cancel(),
	}

	match self.parse_meta_item() {
	Ok(mi) => return Ok(ast::NestedMetaItem::MetaItem(mi)),
	Err(err) => err.cancel(),
	}

	let token = self.token.clone();

	// Check for unquoted idents in meta items, e.g.: #[cfg(key = foo)]
	// `from_expansion()` ensures we don't suggest for cases such as
	// `#[cfg(feature = $expr)]` in macros
	if self.prev_token == token::Eq && !self.token.span.from_expansion() {
	let before = self.token.span.shrink_to_lo();
	while matches!(self.token.kind, token::Ident(..)) {
	self.bump();
	}
	let after = self.prev_token.span.shrink_to_hi();
	let sugg = InvalidMetaItemSuggQuoteIdent { before, after };
	return Err(self.dcx().create_err(InvalidMetaItemUnquotedIdent {
	span: token.span,
	token,
	sugg,
	}));
	}

	Err(self.dcx().create_err(InvalidMetaItem { span: token.span, token }))
	}
	}

	/// The attributes are complete if all attributes are either a doc comment or a builtin attribute other than `cfg_attr`
	pub fn is_complete(attrs: &[ast::Attribute]) -> bool {
	attrs.iter().all(\|attr\| {
	attr.is_doc_comment()
	\|\| attr.ident().is_some_and(\|ident\| {
	ident.name != sym::cfg_attr && rustc_feature::is_builtin_attr_name(ident.name)
	})
	})
	}