Rollup merge of #149903 - JonathanBrouwer:cfg_old_cleanup, r=jdonszelmann

Remove unused code in `cfg_old`

r? ```@jdonszelmann```

Fixes one of the todos from #149865

Author: jhpratt

compiler/rustc_attr_parsing/messages.ftl

@@ -6,9 +6,6 @@ attr_parsing_bundle_needs_static =
 
 attr_parsing_cfg_attr_bad_delim = wrong `cfg_attr` delimiters
 
-attr_parsing_cfg_predicate_identifier =
-    `cfg` predicate key must be an identifier
-
 attr_parsing_deprecated_item_suggestion =
     suggestions on deprecated items are unstable
     .help = add `#![feature(deprecated_suggestion)]` to the crate root
@@ -41,9 +38,6 @@ attr_parsing_empty_link_name =
     link name must not be empty
     .label = empty link name
 
-attr_parsing_expected_one_cfg_pattern =
-    expected 1 cfg-pattern
-
 attr_parsing_expected_single_version_literal =
     expected single version literal
 
@@ -241,12 +235,6 @@ attr_parsing_unstable_cfg_target_compact =
 attr_parsing_unstable_feature_bound_incompatible_stability = item annotated with `#[unstable_feature_bound]` should not be stable
     .help = If this item is meant to be stable, do not use any functions annotated with `#[unstable_feature_bound]`. Otherwise, mark this item as unstable with `#[unstable]`
 
-attr_parsing_unsupported_literal_cfg_boolean =
-    literal in `cfg` predicate value must be a boolean
-attr_parsing_unsupported_literal_cfg_string =
-    literal in `cfg` predicate value must be a string
-attr_parsing_unsupported_literal_generic =
-    unsupported literal
 attr_parsing_unsupported_literal_suggestion =
     consider removing the prefix
 

compiler/rustc_attr_parsing/src/attributes/cfg.rs

@@ -4,7 +4,9 @@ use rustc_ast::token::Delimiter;
 use rustc_ast::tokenstream::DelimSpan;
 use rustc_ast::{AttrItem, Attribute, CRATE_NODE_ID, LitKind, ast, token};
 use rustc_errors::{Applicability, PResult};
-use rustc_feature::{AttrSuggestionStyle, AttributeTemplate, Features, template};
+use rustc_feature::{
+    AttrSuggestionStyle, AttributeTemplate, Features, GatedCfg, find_gated_cfg, template,
+};
 use rustc_hir::attrs::CfgEntry;
 use rustc_hir::lints::AttributeLintKind;
 use rustc_hir::{AttrPath, RustcVersion};
@@ -23,7 +25,7 @@ use crate::session_diagnostics::{
     AttributeParseError, AttributeParseErrorReason, CfgAttrBadDelim, MetaBadDelimSugg,
     ParsedDescription,
 };
-use crate::{AttributeParser, fluent_generated, parse_version, session_diagnostics, try_gate_cfg};
+use crate::{AttributeParser, fluent_generated, parse_version, session_diagnostics};
 
 pub const CFG_TEMPLATE: AttributeTemplate = template!(
     List: &["predicate"],
@@ -410,3 +412,19 @@ fn parse_cfg_attr_internal<'a>(
 
     Ok((cfg_predicate, expanded_attrs))
 }
+
+fn try_gate_cfg(name: Symbol, span: Span, sess: &Session, features: Option<&Features>) {
+    let gate = find_gated_cfg(|sym| sym == name);
+    if let (Some(feats), Some(gated_cfg)) = (features, gate) {
+        gate_cfg(gated_cfg, span, sess, feats);
+    }
+}
+
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+fn gate_cfg(gated_cfg: &GatedCfg, cfg_span: Span, sess: &Session, features: &Features) {
+    let (cfg, feature, has_feature) = gated_cfg;
+    if !has_feature(features) && !cfg_span.allows_unstable(*feature) {
+        let explain = format!("`cfg({cfg})` is experimental and subject to change");
+        feature_err(sess, *feature, cfg_span, explain).emit();
+    }
+}

compiler/rustc_attr_parsing/src/attributes/cfg_old.rs

@@ -32,7 +32,6 @@ mod prelude;
 pub(crate) mod allow_unstable;
 pub(crate) mod body;
 pub(crate) mod cfg;
-pub(crate) mod cfg_old;
 pub(crate) mod cfg_select;
 pub(crate) mod codegen_attrs;
 pub(crate) mod confusables;

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -8,7 +8,7 @@ use rustc_hir::{
 
 use super::prelude::*;
 use super::util::parse_version;
-use crate::session_diagnostics::{self, UnsupportedLiteralReason};
+use crate::session_diagnostics::{self};
 
 macro_rules! reject_outside_std {
     ($cx: ident) => {
@@ -302,12 +302,7 @@ pub(crate) fn parse_stability<S: Stage>(
     for param in list.mixed() {
         let param_span = param.span();
         let Some(param) = param.meta_item() else {
-            cx.emit_err(session_diagnostics::UnsupportedLiteral {
-                span: param_span,
-                reason: UnsupportedLiteralReason::Generic,
-                is_bytestr: false,
-                start_point_span: cx.sess().source_map().start_point(param_span),
-            });
+            cx.unexpected_literal(param.span());
             return None;
         };
 
@@ -382,12 +377,7 @@ pub(crate) fn parse_unstability<S: Stage>(
 
     for param in list.mixed() {
         let Some(param) = param.meta_item() else {
-            cx.emit_err(session_diagnostics::UnsupportedLiteral {
-                span: param.span(),
-                reason: UnsupportedLiteralReason::Generic,
-                is_bytestr: false,
-                start_point_span: cx.sess().source_map().start_point(param.span()),
-            });
+            cx.unexpected_literal(param.span());
             return None;
         };
 

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -107,7 +107,6 @@ pub mod validate_attr;
 pub use attributes::cfg::{
     CFG_TEMPLATE, EvalConfigResult, eval_config_entry, parse_cfg, parse_cfg_attr, parse_cfg_entry,
 };
-pub use attributes::cfg_old::*;
 pub use attributes::cfg_select::*;
 pub use attributes::util::{is_builtin_attr, parse_version};
 pub use context::{Early, Late, OmitDoc, ShouldEmit};