use rustc_ast as ast;
use rustc_ast::token::{self, MetaVarKind};
use rustc_ast::tokenstream::ParserRange;
use rustc_ast::{Attribute, attr};
use rustc_errors::codes::*;
use rustc_errors::{Diag, PResult};
use rustc_span::{BytePos, Span};
use thin_vec::ThinVec;
use tracing::debug;
use super::{
AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle, Trailing, UsePreAttrPos,
};
use crate::{errors, exp, fluent_generated as fluent};
// 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,
}
#[derive(Clone, Copy, PartialEq, Eq)]
pub enum AllowLeadingUnsafe {
Yes,
No,
}
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(exp!(Pound)) {
let prev_outer_attr_sp = outer_attrs.last().map(|attr: &Attribute| 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,
},
true,
) {
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| {
let pound_hi = this.token.span.hi();
assert!(this.eat(exp!(Pound)), "parse_attribute called in non-attribute position");
let not_lo = this.token.span.lo();
let style =
if this.eat(exp!(Bang)) { ast::AttrStyle::Inner } else { ast::AttrStyle::Outer };
let mut bracket_res = this.expect(exp!(OpenBracket));
// If `#!` is not followed by `[`
if let Err(err) = &mut bracket_res
&& style == ast::AttrStyle::Inner
&& pound_hi == not_lo
{
err.note(
"the token sequence `#!` here looks like the start of \
a shebang interpreter directive but it is not",
);
err.help(
"if you meant this to be a shebang interpreter directive, \
move it to the very start of the file",
);
}
bracket_res?;
let item = this.parse_attr_item(ForceCollect::No)?;
this.expect(exp!(CloseBracket))?;
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,
item.is_valid_for_outer_style(),
);
}
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,
suggest_to_outer: bool,
) -> 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 == 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);
if suggest_to_outer {
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,
suggest_to_outer: bool,
) {
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,
suggest_to_outer,
)
.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, force_collect: ForceCollect) -> PResult<'a, ast::AttrItem> {
if let Some(item) = self.eat_metavar_seq_with_matcher(
|mv_kind| matches!(mv_kind, MetaVarKind::Meta { .. }),
|this| this.parse_attr_item(force_collect),
) {
return Ok(item);
}
// Attr items don't have attributes.
self.collect_tokens(None, AttrWrapper::empty(), force_collect, |this, _empty_attrs| {
let is_unsafe = this.eat_keyword(exp!(Unsafe));
let unsafety = if is_unsafe {
let unsafe_span = this.prev_token.span;
this.expect(exp!(OpenParen))?;
ast::Safety::Unsafe(unsafe_span)
} else {
ast::Safety::Default
};
let path = this.parse_path(PathStyle::Mod)?;
let args = this.parse_attr_args()?;
if is_unsafe {
this.expect(exp!(CloseParen))?;
}
Ok((
ast::AttrItem { unsafety, path, args, tokens: None },
Trailing::No,
UsePreAttrPos::No,
))
})
}
/// 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 fn parse_inner_attributes(&mut self) -> PResult<'a, ast::AttrVec> {
let mut attrs = ast::AttrVec::new();
loop {
let start_pos = self.num_bump_calls;
// Only try to parse if it is an inner attribute (has `!`).
let attr = if self.check(exp!(Pound)) && self.look_ahead(1, |t| t == &token::Bang) {
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 {
// If we are currently capturing tokens (i.e. we are within a call to
// `Parser::collect_tokens`) record the token positions of this inner attribute,
// for possible later processing in a `LazyAttrTokenStream`.
if let Capturing::Yes = self.capture_state.capturing {
let end_pos = self.num_bump_calls;
let parser_range = ParserRange(start_pos..end_pos);
self.capture_state.inner_attr_parser_ranges.insert(attr.id, parser_range);
}
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(errors::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::MetaItemInner, Vec<(ast::AttrItem, Span)>)> {
let cfg_predicate = self.parse_meta_item_inner()?;
self.expect(exp!(Comma))?;
// Presumably, the majority of the time there will only be one attr.
let mut expanded_attrs = Vec::with_capacity(1);
while self.token != token::Eof {
let lo = self.token.span;
let item = self.parse_attr_item(ForceCollect::Yes)?;
expanded_attrs.push((item, lo.to(self.prev_token.span)));
if !self.eat(exp!(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::MetaItemInner>> {
// Presumably, the majority of the time there will only be one attr.
let mut nmis = ThinVec::with_capacity(1);
while self.token != token::Eof {
nmis.push(self.parse_meta_item_inner()?);
if !self.eat(exp!(Comma)) {
break;
}
}
Ok(nmis)
}
/// Parse a meta item per RFC 1559.
///
/// ```ebnf
/// MetaItem = SimplePath ( '=' UNSUFFIXED_LIT | '(' MetaSeq? ')' )? ;
/// MetaSeq = MetaItemInner (',' MetaItemInner)* ','? ;
/// ```
pub fn parse_meta_item(
&mut self,
unsafe_allowed: AllowLeadingUnsafe,
) -> PResult<'a, ast::MetaItem> {
if let Some(MetaVarKind::Meta { has_meta_form }) = self.token.is_metavar_seq() {
return if has_meta_form {
let attr_item = self
.eat_metavar_seq(MetaVarKind::Meta { has_meta_form: true }, |this| {
this.parse_attr_item(ForceCollect::No)
})
.unwrap();
Ok(attr_item.meta(attr_item.path.span).unwrap())
} else {
self.unexpected_any()
};
}
let lo = self.token.span;
let is_unsafe = if unsafe_allowed == AllowLeadingUnsafe::Yes {
self.eat_keyword(exp!(Unsafe))
} else {
false
};
let unsafety = if is_unsafe {
let unsafe_span = self.prev_token.span;
self.expect(exp!(OpenParen))?;
ast::Safety::Unsafe(unsafe_span)
} else {
ast::Safety::Default
};
let path = self.parse_path(PathStyle::Mod)?;
let kind = self.parse_meta_item_kind()?;
if is_unsafe {
self.expect(exp!(CloseParen))?;
}
let span = lo.to(self.prev_token.span);
Ok(ast::MetaItem { unsafety, path, kind, span })
}
pub(crate) fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
Ok(if self.eat(exp!(Eq)) {
ast::MetaItemKind::NameValue(self.parse_unsuffixed_meta_item_lit()?)
} else if self.check(exp!(OpenParen)) {
let (list, _) = self.parse_paren_comma_seq(|p| p.parse_meta_item_inner())?;
ast::MetaItemKind::List(list)
} else {
ast::MetaItemKind::Word
})
}
/// Parse an inner meta item per RFC 1559.
///
/// ```ebnf
/// MetaItemInner = UNSUFFIXED_LIT | MetaItem ;
/// ```
pub fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::MetaItemInner> {
match self.parse_unsuffixed_meta_item_lit() {
Ok(lit) => return Ok(ast::MetaItemInner::Lit(lit)),
Err(err) => err.cancel(), // we provide a better error below
}
match self.parse_meta_item(AllowLeadingUnsafe::No) {
Ok(mi) => return Ok(ast::MetaItemInner::MetaItem(mi)),
Err(err) => err.cancel(), // we provide a better error below
}
let mut err = errors::InvalidMetaItem {
span: self.token.span,
descr: super::token_descr(&self.token),
quote_ident_sugg: None,
};
// Suggest quoting idents, e.g. in `#[cfg(key = value)]`. We don't use `Token::ident` and
// don't `uninterpolate` the token to avoid suggesting anything butchered or questionable
// when macro metavariables are involved.
if self.prev_token == token::Eq
&& let token::Ident(..) = self.token.kind
{
let before = self.token.span.shrink_to_lo();
while let token::Ident(..) = self.token.kind {
self.bump();
}
err.quote_ident_sugg = Some(errors::InvalidMetaItemQuoteIdentSugg {
before,
after: self.prev_token.span.shrink_to_hi(),
});
}
Err(self.dcx().create_err(err))
}
}