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Make cfg and cfg_attr trace attributes into early parsed attributes

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This commit is contained in:
Jonathan Brouwer 2025-12-26 20:56:42 +01:00
parent 03fb7eeced
commit 5590fc034c
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GPG key ID: F13E55D38C971DEF
15 changed files with 247 additions and 143 deletions
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8
compiler/rustc_expand/src/config.rs
View file

@ -7,8 +7,8 @@ use rustc_ast::tokenstream::{
AttrTokenStream, AttrTokenTree, LazyAttrTokenStream, Spacing, TokenTree,
};
use rustc_ast::{
self as ast, AttrKind, AttrStyle, Attribute, HasAttrs, HasTokens, MetaItem, MetaItemInner,
NodeId, NormalAttr,
self as ast, AttrItemKind, AttrKind, AttrStyle, Attribute, EarlyParsedAttribute, HasAttrs,
HasTokens, MetaItem, MetaItemInner, NodeId, NormalAttr,
};
use rustc_attr_parsing as attr;
use rustc_attr_parsing::{
@ -288,7 +288,9 @@ impl<'a> StripUnconfigured<'a> {
pub(crate) fn expand_cfg_attr(&self, cfg_attr: &Attribute, recursive: bool) -> Vec<Attribute> {
// A trace attribute left in AST in place of the original `cfg_attr` attribute.
// It can later be used by lints or other diagnostics.
let trace_attr = attr_into_trace(cfg_attr.clone(), sym::cfg_attr_trace);
let mut trace_attr = cfg_attr.clone();
trace_attr.replace_args(AttrItemKind::Parsed(EarlyParsedAttribute::CfgAttrTrace));
let trace_attr = attr_into_trace(trace_attr, sym::cfg_attr_trace);
let Some((cfg_predicate, expanded_attrs)) =
rustc_attr_parsing::parse_cfg_attr(cfg_attr, &self.sess, self.features)

57
compiler/rustc_expand/src/expand.rs
View file

@ -7,12 +7,16 @@ use rustc_ast::mut_visit::*;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::visit::{self, AssocCtxt, Visitor, VisitorResult, try_visit, walk_list};
use rustc_ast::{
self as ast, AssocItemKind, AstNodeWrapper, AttrArgs, AttrStyle, AttrVec, DUMMY_NODE_ID,
ExprKind, ForeignItemKind, HasAttrs, HasNodeId, Inline, ItemKind, MacStmtStyle, MetaItemInner,
MetaItemKind, ModKind, NodeId, PatKind, StmtKind, TyKind, token,
self as ast, AssocItemKind, AstNodeWrapper, AttrArgs, AttrItemKind, AttrStyle, AttrVec,
DUMMY_NODE_ID, EarlyParsedAttribute, ExprKind, ForeignItemKind, HasAttrs, HasNodeId, Inline,
ItemKind, MacStmtStyle, MetaItemInner, MetaItemKind, ModKind, NodeId, PatKind, StmtKind,
TyKind, token,
};
use rustc_ast_pretty::pprust;
use rustc_attr_parsing::{AttributeParser, Early, EvalConfigResult, ShouldEmit, validate_attr};
use rustc_attr_parsing::{
AttributeParser, CFG_TEMPLATE, Early, EvalConfigResult, ShouldEmit, eval_config_entry,
parse_cfg, validate_attr,
};
use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_errors::PResult;
@ -2188,21 +2192,17 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
&& !AttributeParser::<Early>::is_parsed_attribute(&attr.path())
{
let attr_name = attr.name().unwrap();
// `#[cfg]` and `#[cfg_attr]` are special - they are
// eagerly evaluated.
if attr_name != sym::cfg_trace && attr_name != sym::cfg_attr_trace {
self.cx.sess.psess.buffer_lint(
UNUSED_ATTRIBUTES,
attr.span,
self.cx.current_expansion.lint_node_id,
crate::errors::UnusedBuiltinAttribute {
attr_name,
macro_name: pprust::path_to_string(&call.path),
invoc_span: call.path.span,
attr_span: attr.span,
},
);
}
self.cx.sess.psess.buffer_lint(
UNUSED_ATTRIBUTES,
attr.span,
self.cx.current_expansion.lint_node_id,
crate::errors::UnusedBuiltinAttribute {
attr_name,
macro_name: pprust::path_to_string(&call.path),
invoc_span: call.path.span,
attr_span: attr.span,
},
);
}
}
}
@ -2213,11 +2213,26 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
attr: ast::Attribute,
pos: usize,
) -> EvalConfigResult {
let res = self.cfg().cfg_true(&attr, ShouldEmit::ErrorsAndLints);
let Some(cfg) = AttributeParser::parse_single(
self.cfg().sess,
&attr,
attr.span,
self.cfg().lint_node_id,
self.cfg().features,
ShouldEmit::ErrorsAndLints,
parse_cfg,
&CFG_TEMPLATE,
) else {
// Cfg attribute was not parsable, give up
return EvalConfigResult::True;
};
let res = eval_config_entry(self.cfg().sess, &cfg);
if res.as_bool() {
// A trace attribute left in AST in place of the original `cfg` attribute.
// It can later be used by lints or other diagnostics.
let trace_attr = attr_into_trace(attr, sym::cfg_trace);
let mut trace_attr = attr_into_trace(attr, sym::cfg_trace);
trace_attr.replace_args(AttrItemKind::Parsed(EarlyParsedAttribute::CfgTrace(cfg)));
node.visit_attrs(|attrs| attrs.insert(pos, trace_attr));
}