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Port #[cfg_attr] to the new attribute parsing infrastructure

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Signed-off-by: Jonathan Brouwer <jonathantbrouwer@gmail.com>
This commit is contained in:
Jonathan Brouwer
2025-10-03 13:24:45 +02:00
parent e0c190f681
commit 7113d58c8e
6 changed files with 171 additions and 82 deletions
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12
compiler/rustc_attr_parsing/messages.ftl
View File

@@ -4,6 +4,8 @@ attr_parsing_as_needed_compatibility =
attr_parsing_bundle_needs_static =
linking modifier `bundle` is only compatible with `static` linking kind
attr_parsing_cfg_attr_bad_delim = wrong `cfg_attr` delimiters
attr_parsing_cfg_predicate_identifier =
`cfg` predicate key must be an identifier
@@ -264,13 +266,3 @@ attr_parsing_unused_multiple =
attr_parsing_whole_archive_needs_static =
linking modifier `whole-archive` is only compatible with `static` linking kind
attr_parsing_limit_invalid =
`limit` must be a non-negative integer
.label = {$error_str}
attr_parsing_cfg_attr_bad_delim = wrong `cfg_attr` delimiters
attr_parsing_malformed_cfg_attr = malformed `cfg_attr` attribute input
.suggestion = missing condition and attribute
.note = for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>

115
compiler/rustc_attr_parsing/src/attributes/cfg.rs
View File

@@ -1,10 +1,10 @@
use rustc_ast::token::Delimiter;
use rustc_ast::tokenstream::DelimSpan;
use rustc_ast::{AttrItem, Attribute, LitKind, MetaItemInner, NodeId, ast, token};
use rustc_errors::PResult;
use rustc_ast::{AttrItem, Attribute, CRATE_NODE_ID, LitKind, NodeId, ast, token};
use rustc_errors::{Applicability, PResult};
use rustc_feature::{AttributeTemplate, Features, template};
use rustc_hir::RustcVersion;
use rustc_hir::attrs::CfgEntry;
use rustc_hir::{AttrPath, RustcVersion};
use rustc_parse::parser::{ForceCollect, Parser};
use rustc_parse::{exp, parse_in};
use rustc_session::Session;
@@ -17,9 +17,12 @@ use thin_vec::ThinVec;
use crate::context::{AcceptContext, ShouldEmit, Stage};
use crate::parser::{ArgParser, MetaItemListParser, MetaItemOrLitParser, NameValueParser};
use crate::session_diagnostics::{CfgAttrBadDelim, MalformedCfgAttr, MetaBadDelimSugg};
use crate::session_diagnostics::{
AttributeParseError, AttributeParseErrorReason, CfgAttrBadDelim, MetaBadDelimSugg,
};
use crate::{
CfgMatchesLintEmitter, fluent_generated, parse_version, session_diagnostics, try_gate_cfg,
AttributeParser, CfgMatchesLintEmitter, fluent_generated, parse_version, session_diagnostics,
try_gate_cfg,
};
pub const CFG_TEMPLATE: AttributeTemplate = template!(
@@ -27,6 +30,11 @@ pub const CFG_TEMPLATE: AttributeTemplate = template!(
"https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute"
);
const CFG_ATTR_TEMPLATE: AttributeTemplate = template!(
List: &["predicate, attr1, attr2, ..."],
"https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute"
);
pub fn parse_cfg<'c, S: Stage>(
cx: &'c mut AcceptContext<'_, '_, S>,
args: &'c ArgParser<'_>,
@@ -76,9 +84,7 @@ pub(crate) fn parse_cfg_entry<S: Stage>(
},
a @ (ArgParser::NoArgs | ArgParser::NameValue(_)) => {
let Some(name) = meta.path().word_sym() else {
cx.emit_err(session_diagnostics::CfgPredicateIdentifier {
span: meta.path().span(),
});
cx.expected_identifier(meta.path().span());
return None;
};
parse_name_value(name, meta.path().span(), a.name_value(), meta.span(), cx)?
@@ -87,7 +93,7 @@ pub(crate) fn parse_cfg_entry<S: Stage>(
MetaItemOrLitParser::Lit(lit) => match lit.kind {
LitKind::Bool(b) => CfgEntry::Bool(b, lit.span),
_ => {
cx.emit_err(session_diagnostics::CfgPredicateIdentifier { span: lit.span });
cx.expected_identifier(lit.span);
return None;
}
},
@@ -155,9 +161,7 @@ fn parse_cfg_entry_target<S: Stage>(
// Then, parse it as a name-value item
let Some(name) = sub_item.path().word_sym() else {
cx.emit_err(session_diagnostics::CfgPredicateIdentifier {
span: sub_item.path().span(),
});
cx.expected_identifier(sub_item.path().span());
return None;
};
let name = Symbol::intern(&format!("target_{name}"));
@@ -309,32 +313,51 @@ impl EvalConfigResult {
pub fn parse_cfg_attr(
cfg_attr: &Attribute,
psess: &ParseSess,
) -> Option<(MetaItemInner, Vec<(AttrItem, Span)>)> {
const CFG_ATTR_GRAMMAR_HELP: &str = "#[cfg_attr(condition, attribute, other_attribute, ...)]";
const CFG_ATTR_NOTE_REF: &str = "for more information, visit \
<https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>";
sess: &Session,
features: Option<&Features>,
) -> Option<(CfgEntry, Vec<(AttrItem, Span)>)> {
match cfg_attr.get_normal_item().args {
ast::AttrArgs::Delimited(ast::DelimArgs { dspan, delim, ref tokens })
if !tokens.is_empty() =>
{
check_cfg_attr_bad_delim(psess, dspan, delim);
match parse_in(psess, tokens.clone(), "`cfg_attr` input", |p| {
parse_cfg_attr_internal(p)
check_cfg_attr_bad_delim(&sess.psess, dspan, delim);
match parse_in(&sess.psess, tokens.clone(), "`cfg_attr` input", |p| {
parse_cfg_attr_internal(p, sess, features, cfg_attr)
}) {
Ok(r) => return Some(r),
Err(e) => {
e.with_help(format!("the valid syntax is `{CFG_ATTR_GRAMMAR_HELP}`"))
.with_note(CFG_ATTR_NOTE_REF)
.emit();
let suggestions = CFG_ATTR_TEMPLATE.suggestions(cfg_attr.style, sym::cfg_attr);
e.with_span_suggestions(
cfg_attr.span,
"must be of the form",
suggestions,
Applicability::HasPlaceholders,
)
.with_note(format!(
"for more information, visit <{}>",
CFG_ATTR_TEMPLATE.docs.expect("cfg_attr has docs")
))
.emit();
}
}
}
_ => {
psess
.dcx()
.emit_err(MalformedCfgAttr { span: cfg_attr.span, sugg: CFG_ATTR_GRAMMAR_HELP });
let (span, reason) = if let ast::AttrArgs::Delimited(ast::DelimArgs { dspan, .. }) =
cfg_attr.get_normal_item().args
{
(dspan.entire(), AttributeParseErrorReason::ExpectedAtLeastOneArgument)
} else {
(cfg_attr.span, AttributeParseErrorReason::ExpectedList)
};
sess.dcx().emit_err(AttributeParseError {
span,
attr_span: cfg_attr.span,
template: CFG_ATTR_TEMPLATE,
attribute: AttrPath::from_ast(&cfg_attr.get_normal_item().path),
reason,
attr_style: cfg_attr.style,
});
}
}
None
@@ -353,8 +376,42 @@ fn check_cfg_attr_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter
/// Parses `cfg_attr(pred, attr_item_list)` where `attr_item_list` is comma-delimited.
fn parse_cfg_attr_internal<'a>(
parser: &mut Parser<'a>,
) -> PResult<'a, (ast::MetaItemInner, Vec<(ast::AttrItem, Span)>)> {
let cfg_predicate = parser.parse_meta_item_inner()?;
sess: &'a Session,
features: Option<&Features>,
attribute: &Attribute,
) -> PResult<'a, (CfgEntry, Vec<(ast::AttrItem, Span)>)> {
// Parse cfg predicate
let pred_start = parser.token.span;
let meta = MetaItemOrLitParser::parse_single(parser, ShouldEmit::ErrorsAndLints)?;
let pred_span = pred_start.with_hi(parser.token.span.hi());
let cfg_predicate = AttributeParser::parse_single_args(
sess,
attribute.span,
attribute.style,
AttrPath {
segments: attribute
.ident_path()
.expect("cfg_attr is not a doc comment")
.into_boxed_slice(),
span: attribute.span,
},
pred_span,
CRATE_NODE_ID,
features,
ShouldEmit::ErrorsAndLints,
&meta,
parse_cfg_entry,
&CFG_ATTR_TEMPLATE,
)
.ok_or_else(|| {
let mut diag = sess.dcx().struct_err(
"cfg_entry parsing failing with `ShouldEmit::ErrorsAndLints` should emit a error.",
);
diag.downgrade_to_delayed_bug();
diag
})?;
parser.expect(exp!(Comma))?;
// Presumably, the majority of the time there will only be one attr.

64
compiler/rustc_attr_parsing/src/interface.rs
View File

@@ -1,7 +1,7 @@
use std::borrow::Cow;
use rustc_ast as ast;
use rustc_ast::NodeId;
use rustc_ast::{AttrStyle, NodeId};
use rustc_errors::DiagCtxtHandle;
use rustc_feature::{AttributeTemplate, Features};
use rustc_hir::attrs::AttributeKind;
@@ -62,7 +62,8 @@ impl<'sess> AttributeParser<'sess, Early> {
)
}
/// Usually you want `parse_limited`, which defaults to no errors.
/// This does the same as `parse_limited`, except it has a `should_emit` parameter which allows it to emit errors.
/// Usually you want `parse_limited`, which emits no errors.
pub fn parse_limited_should_emit(
sess: &'sess Session,
attrs: &[ast::Attribute],
@@ -86,6 +87,13 @@ impl<'sess> AttributeParser<'sess, Early> {
parsed.pop()
}
/// This method allows you to parse a list of attributes *before* `rustc_ast_lowering`.
/// This can be used for attributes that would be removed before `rustc_ast_lowering`, such as attributes on macro calls.
///
/// Try to use this as little as possible. Attributes *should* be lowered during
/// `rustc_ast_lowering`. Some attributes require access to features to parse, which would
/// crash if you tried to do so through [`parse_limited_all`](Self::parse_limited_all).
/// Therefore, if `parse_only` is None, then features *must* be provided.
pub fn parse_limited_all(
sess: &'sess Session,
attrs: &[ast::Attribute],
@@ -111,6 +119,8 @@ impl<'sess> AttributeParser<'sess, Early> {
)
}
/// This method parses a single attribute, using `parse_fn`.
/// This is useful if you already know what exact attribute this is, and want to parse it.
pub fn parse_single<T>(
sess: &'sess Session,
attr: &ast::Attribute,
@@ -121,13 +131,6 @@ impl<'sess> AttributeParser<'sess, Early> {
parse_fn: fn(cx: &mut AcceptContext<'_, '_, Early>, item: &ArgParser<'_>) -> Option<T>,
template: &AttributeTemplate,
) -> Option<T> {
let mut parser = Self {
features,
tools: Vec::new(),
parse_only: None,
sess,
stage: Early { emit_errors },
};
let ast::AttrKind::Normal(normal_attr) = &attr.kind else {
panic!("parse_single called on a doc attr")
};
@@ -136,6 +139,43 @@ impl<'sess> AttributeParser<'sess, Early> {
let meta_parser = MetaItemParser::from_attr(normal_attr, &parts, &sess.psess, emit_errors)?;
let path = meta_parser.path();
let args = meta_parser.args();
Self::parse_single_args(
sess,
attr.span,
attr.style,
path.get_attribute_path(),
target_span,
target_node_id,
features,
emit_errors,
args,
parse_fn,
template,
)
}
/// This method is equivalent to `parse_single`, but parses arguments using `parse_fn` using manually created `args`.
/// This is useful when you want to parse other things than attributes using attribute parsers.
pub fn parse_single_args<T, I>(
sess: &'sess Session,
attr_span: Span,
attr_style: AttrStyle,
attr_path: AttrPath,
target_span: Span,
target_node_id: NodeId,
features: Option<&'sess Features>,
emit_errors: ShouldEmit,
args: &I,
parse_fn: fn(cx: &mut AcceptContext<'_, '_, Early>, item: &I) -> Option<T>,
template: &AttributeTemplate,
) -> Option<T> {
let mut parser = Self {
features,
tools: Vec::new(),
parse_only: None,
sess,
stage: Early { emit_errors },
};
let mut cx: AcceptContext<'_, 'sess, Early> = AcceptContext {
shared: SharedContext {
cx: &mut parser,
@@ -145,10 +185,10 @@ impl<'sess> AttributeParser<'sess, Early> {
crate::lints::emit_attribute_lint(&lint, sess);
},
},
attr_span: attr.span,
attr_style: attr.style,
attr_span,
attr_style,
template,
attr_path: path.get_attribute_path(),
attr_path,
};
parse_fn(&mut cx, args)
}

40
compiler/rustc_attr_parsing/src/parser.rs
View File

@@ -8,7 +8,7 @@ use std::fmt::{Debug, Display};
use rustc_ast::token::{self, Delimiter, MetaVarKind};
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{AttrArgs, DelimArgs, Expr, ExprKind, LitKind, MetaItemLit, NormalAttr, Path};
use rustc_ast::{AttrArgs, Expr, ExprKind, LitKind, MetaItemLit, NormalAttr, Path};
use rustc_ast_pretty::pprust;
use rustc_errors::{Diag, PResult};
use rustc_hir::{self as hir, AttrPath};
@@ -124,7 +124,11 @@ impl<'a> ArgParser<'a> {
return None;
}
Self::List(MetaItemListParser::new(args, psess, should_emit)?)
Self::List(
MetaItemListParser::new(&args.tokens, args.dspan.entire(), psess, should_emit)
.map_err(|e| should_emit.emit_err(e))
.ok()?,
)
}
AttrArgs::Eq { eq_span, expr } => Self::NameValue(NameValueParser {
eq_span: *eq_span,
@@ -186,7 +190,15 @@ pub enum MetaItemOrLitParser<'a> {
Err(Span, ErrorGuaranteed),
}
impl<'a> MetaItemOrLitParser<'a> {
impl<'sess> MetaItemOrLitParser<'sess> {
pub fn parse_single(
parser: &mut Parser<'sess>,
should_emit: ShouldEmit,
) -> PResult<'sess, MetaItemOrLitParser<'static>> {
let mut this = MetaItemListParserContext { parser, should_emit };
this.parse_meta_item_inner()
}
pub fn span(&self) -> Span {
match self {
MetaItemOrLitParser::MetaItemParser(generic_meta_item_parser) => {
@@ -204,7 +216,7 @@ impl<'a> MetaItemOrLitParser<'a> {
}
}
pub fn meta_item(&self) -> Option<&MetaItemParser<'a>> {
pub fn meta_item(&self) -> Option<&MetaItemParser<'sess>> {
match self {
MetaItemOrLitParser::MetaItemParser(parser) => Some(parser),
_ => None,
@@ -542,23 +554,13 @@ pub struct MetaItemListParser<'a> {
}
impl<'a> MetaItemListParser<'a> {
fn new<'sess>(
delim: &'a DelimArgs,
pub(crate) fn new<'sess>(
tokens: &'a TokenStream,
span: Span,
psess: &'sess ParseSess,
should_emit: ShouldEmit,
) -> Option<Self> {
match MetaItemListParserContext::parse(
delim.tokens.clone(),
psess,
delim.dspan.entire(),
should_emit,
) {
Ok(s) => Some(s),
Err(e) => {
should_emit.emit_err(e);
None
}
}
) -> Result<Self, Diag<'sess>> {
MetaItemListParserContext::parse(tokens.clone(), psess, span, should_emit)
}
/// Lets you pick and choose as what you want to parse each element in the list

10
compiler/rustc_attr_parsing/src/session_diagnostics.rs
View File

@@ -980,13 +980,3 @@ pub(crate) struct CfgAttrBadDelim {
#[subdiagnostic]
pub sugg: MetaBadDelimSugg,
}
#[derive(Diagnostic)]
#[diag(attr_parsing_malformed_cfg_attr)]
#[note]
pub(crate) struct MalformedCfgAttr {
#[primary_span]
#[suggestion(style = "verbose", code = "{sugg}")]
pub span: Span,
pub sugg: &'static str,
}

12
compiler/rustc_expand/src/config.rs
View File

@@ -303,7 +303,7 @@ impl<'a> StripUnconfigured<'a> {
let trace_attr = attr_into_trace(cfg_attr.clone(), sym::cfg_attr_trace);
let Some((cfg_predicate, expanded_attrs)) =
rustc_attr_parsing::parse_cfg_attr(cfg_attr, &self.sess.psess)
rustc_attr_parsing::parse_cfg_attr(cfg_attr, &self.sess, self.features)
else {
return vec![trace_attr];
};
@@ -318,7 +318,15 @@ impl<'a> StripUnconfigured<'a> {
);
}
if !attr::cfg_matches(&cfg_predicate, &self.sess, self.lint_node_id, self.features) {
if !attr::eval_config_entry(
self.sess,
&cfg_predicate,
ast::CRATE_NODE_ID,
self.features,
ShouldEmit::ErrorsAndLints,
)
.as_bool()
{
return vec![trace_attr];
}