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update cfg_select! documentation

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and make internal terminology consistent

Co-authored-by: Travis Cross <tc@traviscross.com>
This commit is contained in:
Folkert de Vries
2025-07-14 11:03:16 +02:00
parent 9c3064e131
commit d0153f5872
6 changed files with 39 additions and 30 deletions
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16
compiler/rustc_builtin_macros/src/cfg_select.rs
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@@ -1,12 +1,12 @@
use rustc_ast::tokenstream::TokenStream;
use rustc_attr_parsing as attr;
use rustc_expand::base::{DummyResult, ExpandResult, ExtCtxt, MacroExpanderResult};
use rustc_parse::parser::cfg_select::{CfgSelectBranches, CfgSelectRule, parse_cfg_select};
use rustc_parse::parser::cfg_select::{CfgSelectBranches, CfgSelectPredicate, parse_cfg_select};
use rustc_span::{Ident, Span, sym};
use crate::errors::{CfgSelectNoMatches, CfgSelectUnreachable};
/// Selects the first arm whose rule evaluates to true.
/// Selects the first arm whose predicate evaluates to true.
fn select_arm(ecx: &ExtCtxt<'_>, branches: CfgSelectBranches) -> Option<(TokenStream, Span)> {
for (cfg, tt, arm_span) in branches.reachable {
if attr::cfg_matches(
@@ -30,11 +30,11 @@ pub(super) fn expand_cfg_select<'cx>(
ExpandResult::Ready(match parse_cfg_select(&mut ecx.new_parser_from_tts(tts)) {
Ok(branches) => {
if let Some((underscore, _, _)) = branches.wildcard {
// Warn for every unreachable rule. We store the fully parsed branch for rustfmt.
for (rule, _, _) in &branches.unreachable {
let span = match rule {
CfgSelectRule::Wildcard(underscore) => underscore.span,
CfgSelectRule::Cfg(cfg) => cfg.span(),
// Warn for every unreachable predicate. We store the fully parsed branch for rustfmt.
for (predicate, _, _) in &branches.unreachable {
let span = match predicate {
CfgSelectPredicate::Wildcard(underscore) => underscore.span,
CfgSelectPredicate::Cfg(cfg) => cfg.span(),
};
let err = CfgSelectUnreachable { span, wildcard_span: underscore.span };
ecx.dcx().emit_warn(err);
@@ -50,7 +50,7 @@ pub(super) fn expand_cfg_select<'cx>(
Ident::with_dummy_span(sym::cfg_select),
);
} else {
// Emit a compiler error when none of the rules matched.
// Emit a compiler error when none of the predicates matched.
let guar = ecx.dcx().emit_err(CfgSelectNoMatches { span: sp });
DummyResult::any(sp, guar)
}