Use reason for tracked item diagnostics from cfg_select!

compiler/rustc_attr_parsing/src/attributes/cfg.rs

@@ -237,42 +237,39 @@ pub fn eval_config_entry(sess: &Session, cfg_entry: &CfgEntry) -> EvalConfigResu
             }
             EvalConfigResult::True
         }
-        CfgEntry::Any(subs, span) => {
+        CfgEntry::Any(subs, _) => {
             for sub in subs {
                 let res = eval_config_entry(sess, sub);
                 if res.as_bool() {
                     return res;
                 }
             }
-            EvalConfigResult::False { reason: cfg_entry.clone(), reason_span: *span }
+            EvalConfigResult::False { reason: cfg_entry.clone() }
         }
-        CfgEntry::Not(sub, span) => {
+        CfgEntry::Not(sub, _) => {
             if eval_config_entry(sess, sub).as_bool() {
-                EvalConfigResult::False { reason: cfg_entry.clone(), reason_span: *span }
+                EvalConfigResult::False { reason: cfg_entry.clone() }
             } else {
                 EvalConfigResult::True
             }
         }
-        CfgEntry::Bool(b, span) => {
+        CfgEntry::Bool(b, _) => {
             if *b {
                 EvalConfigResult::True
             } else {
-                EvalConfigResult::False { reason: cfg_entry.clone(), reason_span: *span }
+                EvalConfigResult::False { reason: cfg_entry.clone() }
             }
         }
-        CfgEntry::NameValue { name, value, span } => {
+        CfgEntry::NameValue { name, value, span: _ } => {
             if sess.config.contains(&(*name, *value)) {
                 EvalConfigResult::True
             } else {
-                EvalConfigResult::False { reason: cfg_entry.clone(), reason_span: *span }
+                EvalConfigResult::False { reason: cfg_entry.clone() }
             }
         }
-        CfgEntry::Version(min_version, version_span) => {
+        CfgEntry::Version(min_version, _) => {
             let Some(min_version) = min_version else {
-                return EvalConfigResult::False {
-                    reason: cfg_entry.clone(),
-                    reason_span: *version_span,
-                };
+                return EvalConfigResult::False { reason: cfg_entry.clone() };
             };
             // See https://github.com/rust-lang/rust/issues/64796#issuecomment-640851454 for details
             let min_version_ok = if sess.opts.unstable_opts.assume_incomplete_release {
@@ -283,15 +280,15 @@ pub fn eval_config_entry(sess: &Session, cfg_entry: &CfgEntry) -> EvalConfigResu
             if min_version_ok {
                 EvalConfigResult::True
             } else {
-                EvalConfigResult::False { reason: cfg_entry.clone(), reason_span: *version_span }
+                EvalConfigResult::False { reason: cfg_entry.clone() }
             }
         }
     }
 }
 
 pub enum EvalConfigResult {
     True,
-    False { reason: CfgEntry, reason_span: Span },
+    False { reason: CfgEntry },
 }
 
 impl EvalConfigResult {

compiler/rustc_attr_parsing/src/attributes/cfg_select.rs

@@ -15,7 +15,8 @@ use rustc_span::{ErrorGuaranteed, Span, Symbol, sym};
 use crate::attributes::AttributeSafety;
 use crate::parser::{AllowExprMetavar, MetaItemOrLitParser};
 use crate::{
-    AttributeParser, AttributeTemplate, ParsedDescription, ShouldEmit, diagnostics, parse_cfg_entry,
+    AttributeParser, AttributeTemplate, EvalConfigResult, ParsedDescription, ShouldEmit,
+    diagnostics, parse_cfg_entry,
 };
 
 #[derive(Clone)]
@@ -49,11 +50,16 @@ impl CfgSelectBranches {
     /// or the wildcard if none of the reachable branches satisfied the predicate.
     pub fn pop_first_match<F>(&mut self, predicate: F) -> Option<(CfgEntry, TokenStream, Span)>
     where
-        F: Fn(&CfgEntry) -> bool,
+        F: Fn(&CfgEntry) -> EvalConfigResult,
     {
-        for (index, (cfg, _, _)) in self.reachable.iter().enumerate() {
-            if predicate(cfg) {
-                return Some(self.reachable.remove(index));
+        for (index, (cfg, _, _)) in self.reachable.iter_mut().enumerate() {
+            match predicate(cfg) {
+                EvalConfigResult::True => {
+                    return Some(self.reachable.remove(index));
+                }
+                EvalConfigResult::False { reason } => {
+                    *cfg = reason;
+                }
             }
         }
 

compiler/rustc_builtin_macros/src/cfg_select.rs

@@ -3,7 +3,7 @@ use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::{AttrKind, Expr, SyntheticAttr, ast};
 use rustc_attr_ir::CfgEntry;
 use rustc_attr_parsing as attr;
-use rustc_attr_parsing::{CfgSelectBranches, EvalConfigResult, parse_cfg_select};
+use rustc_attr_parsing::{CfgSelectBranches, parse_cfg_select};
 use rustc_expand::base::{DummyResult, ExpandResult, ExtCtxt, MacResult, MacroExpanderResult};
 use rustc_expand::expand::DeclaredIdents;
 use rustc_span::{Ident, Span, sym};
@@ -129,9 +129,7 @@ pub(super) fn expand_cfg_select<'cx>(
         ) {
             Ok(mut branches) => {
                 if let Some((cfg_entry, selected_tts, selected_span)) =
-                    branches.pop_first_match(|cfg| {
-                        matches!(attr::eval_config_entry(ecx.sess, cfg), EvalConfigResult::True)
-                    })
+                    branches.pop_first_match(|cfg| attr::eval_config_entry(ecx.sess, cfg))
                 {
                     let mac = CfgSelectResult {
                         ecx,

compiler/rustc_expand/src/expand.rs

@@ -2366,13 +2366,13 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         let res = self.expand_cfg_true(&mut node, attr, pos);
                         match res {
                             EvalConfigResult::True => continue,
-                            EvalConfigResult::False { reason, reason_span } => {
+                            EvalConfigResult::False { reason } => {
                                 for ident in node.declared_idents() {
                                     self.cx.resolver.append_stripped_cfg_item(
                                         self.cx.current_expansion.lint_node_id,
                                         ident,
                                         reason.clone(),
-                                        reason_span,
+                                        reason.span(),
                                     )
                                 }
                             }

tests/ui/macros/cfg_select.rs

@@ -1,3 +1,4 @@
+//@ compile-flags: --check-cfg 'cfg(feature, values("meow"))'
 #![crate_type = "lib"]
 #![warn(unreachable_cfg_select_predicates)] // Unused warnings are disabled by default in UI tests.
 
@@ -251,3 +252,31 @@ cfg_select! {
     debug_assertions => {}
     _ => {}
 }
+
+cfg_select! {
+    all(true, false) => {
+        struct Thing1;
+    }
+    _ => {}
+}
+
+cfg_select! {
+    feature = "meow" => {
+        struct Thing2;
+    }
+    _ => {}
+}
+
+cfg_select! {
+    all(true, feature = "meow") => {
+        struct Thing2;
+    }
+    _ => {}
+}
+
+fn usages() {
+    let t1: Thing1;
+    //~^ ERROR cannot find type `Thing1` in this scope [E0425]
+    let t2: Thing2;
+    //~^ ERROR cannot find type `Thing2` in this scope [E0425]
+}