bjoernager/rust
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Rollup merge of #131034 - Urgau:cfg-true-false, r=nnethercote

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Implement RFC3695 Allow boolean literals as cfg predicates

This PR implements https://github.com/rust-lang/rfcs/pull/3695: allow boolean literals as cfg predicates, i.e. `cfg(true)` and `cfg(false)`.

r? `@nnethercote` *(or anyone with parser knowledge)*
cc `@clubby789`
This commit is contained in:
Guillaume Gomez 2024-10-04 15:42:53 +02:00 • committed by GitHub
commit 2ceeeb159d
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26 changed files with 284 additions and 58 deletions
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4
compiler/rustc_parse/src/lib.rs
View file

@ -18,7 +18,7 @@ use std::path::Path;
use rustc_ast as ast;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::{AttrItem, Attribute, MetaItem, token};
use rustc_ast::{AttrItem, Attribute, NestedMetaItem, token};
use rustc_ast_pretty::pprust;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Diag, FatalError, PResult};
@ -160,7 +160,7 @@ pub fn fake_token_stream_for_crate(psess: &ParseSess, krate: &ast::Crate) -> Tok
pub fn parse_cfg_attr(
cfg_attr: &Attribute,
psess: &ParseSess,
) -> Option<(MetaItem, Vec<(AttrItem, Span)>)> {
) -> Option<(NestedMetaItem, 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>";

8
compiler/rustc_parse/src/parser/attr.rs
View file

@ -356,8 +356,10 @@ impl<'a> Parser<'a> {
}
/// 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(AllowLeadingUnsafe::No)?;
pub fn parse_cfg_attr(
&mut self,
) -> PResult<'a, (ast::NestedMetaItem, Vec<(ast::AttrItem, Span)>)> {
let cfg_predicate = self.parse_meta_item_inner()?;
self.expect(&token::Comma)?;
// Presumably, the majority of the time there will only be one attr.
@ -452,7 +454,7 @@ impl<'a> Parser<'a> {
/// ```ebnf
/// MetaItemInner = UNSUFFIXED_LIT | MetaItem ;
/// ```
fn parse_meta_item_inner(&mut self) -> PResult<'a, ast::NestedMetaItem> {
pub 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(), // we provide a better error below