Continue improvements on the --check-cfg implementation

- Test the combinations of --check-cfg with partial values() and --cfg
- Test that we detect unexpected value when none are expected

4 files changed, 46 insertions, 54 deletions

diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index 503e172b687..50eb6b6e5da 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -462,7 +462,8 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
                 true
             }
             MetaItemKind::NameValue(..) | MetaItemKind::Word => {
-                let name = cfg.ident().expect("multi-segment cfg predicate").name;
+                let ident = cfg.ident().expect("multi-segment cfg predicate");
+                let name = ident.name;
                 let value = cfg.value_str();
                 if let Some(names_valid) = &sess.check_config.names_valid {
                     if !names_valid.contains(&name) {
@@ -471,30 +472,24 @@ pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Feat
                             cfg.span,
                             CRATE_NODE_ID,
                             "unexpected `cfg` condition name",
-                            BuiltinLintDiagnostics::UnexpectedCfg(
-                                cfg.ident().unwrap().span,
-                                name,
-                                None,
-                            ),
+                            BuiltinLintDiagnostics::UnexpectedCfg(ident.span, name, None),
                         );
                     }
                 }
-                if let Some(val) = value {
-                    if let Some(values_valid) = &sess.check_config.values_valid {
-                        if let Some(values) = values_valid.get(&name) {
-                            if !values.contains(&val) {
-                                sess.buffer_lint_with_diagnostic(
-                                    UNEXPECTED_CFGS,
-                                    cfg.span,
-                                    CRATE_NODE_ID,
-                                    "unexpected `cfg` condition value",
-                                    BuiltinLintDiagnostics::UnexpectedCfg(
-                                        cfg.name_value_literal_span().unwrap(),
-                                        name,
-                                        Some(val),
-                                    ),
-                                );
-                            }
+                if let Some(value) = value {
+                    if let Some(values) = &sess.check_config.values_valid.get(&name) {
+                        if !values.contains(&value) {
+                            sess.buffer_lint_with_diagnostic(
+                                UNEXPECTED_CFGS,
+                                cfg.span,
+                                CRATE_NODE_ID,
+                                "unexpected `cfg` condition value",
+                                BuiltinLintDiagnostics::UnexpectedCfg(
+                                    cfg.name_value_literal_span().unwrap(),
+                                    name,
+                                    Some(value),
+                                ),
+                            );
                         }
                     }
                 }
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 5e0d59bf1b1..91ced2a2d90 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -183,12 +183,10 @@ pub fn parse_check_cfg(specs: Vec<String>) -> CheckCfg {
                             } else if meta_item.has_name(sym::values) {
                                 if let Some((name, values)) = args.split_first() {
                                     if name.is_word() && name.ident().is_some() {
-                                        let values_valid = cfg
-                                            .values_valid
-                                            .get_or_insert_with(|| FxHashMap::default());
                                         let ident = name.ident().expect("multi-segment cfg key");
-                                        let ident_values = values_valid
-                                            .entry(ident.to_string())
+                                        let ident_values = cfg
+                                            .values_valid
+                                            .entry(ident.name.to_string())
                                             .or_insert_with(|| FxHashSet::default());
 
                                         for val in values {
@@ -225,10 +223,8 @@ pub fn parse_check_cfg(specs: Vec<String>) -> CheckCfg {
             );
         }
 
-        if let Some(values_valid) = &cfg.values_valid {
-            if let Some(names_valid) = &mut cfg.names_valid {
-                names_valid.extend(values_valid.keys().cloned());
-            }
+        if let Some(names_valid) = &mut cfg.names_valid {
+            names_valid.extend(cfg.values_valid.keys().cloned());
         }
         cfg
     })
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 72a3f5d5fc9..5f07cf08c2e 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -768,17 +768,14 @@ pub trait LintContext: Sized {
                     db.note("see the asm section of Rust By Example <https://doc.rust-lang.org/nightly/rust-by-example/unsafe/asm.html#labels> for more information");
                 },
                 BuiltinLintDiagnostics::UnexpectedCfg(span, name, value) => {
-                    let mut possibilities: Vec<Symbol> = if value.is_some() {
-                        let Some(values_valid) = &sess.parse_sess.check_config.values_valid else {
-                            bug!("it shouldn't be possible to have a diagnostic on a value if values checking is not enable");
-                        };
-                        let Some(values) = values_valid.get(&name) else {
+                    let possibilities: Vec<Symbol> = if value.is_some() {
+                        let Some(values) = &sess.parse_sess.check_config.values_valid.get(&name) else {
                             bug!("it shouldn't be possible to have a diagnostic on a value whose name is not in values");
                         };
                         values.iter().map(|&s| s).collect()
                     } else {
                         let Some(names_valid) = &sess.parse_sess.check_config.names_valid else {
-                            bug!("it shouldn't be possible to have a diagnostic on a value if values checking is not enable");
+                            bug!("it shouldn't be possible to have a diagnostic on a name if name checking is not enabled");
                         };
                         names_valid.iter().map(|s| *s).collect()
                     };
@@ -786,17 +783,21 @@ pub trait LintContext: Sized {
                     // Show the full list if all possible values for a given name, but don't do it
                     // for names as the possibilities could be very long
                     if value.is_some() {
-                        // Sorting can take some time, so we only do it if required
-                        possibilities.sort();
+                        if !possibilities.is_empty() {
+                            let mut possibilities = possibilities.iter().map(Symbol::as_str).collect::<Vec<_>>();
+                            possibilities.sort();
 
-                        let possibilities = possibilities.iter().map(Symbol::as_str).intersperse(", ").collect::<String>();
-                        db.note(&format!("possible values for `{name}` are: {possibilities}"));
+                            let possibilities = possibilities.join(", ");
+                            db.note(&format!("expected values for `{name}` are: {possibilities}"));
+                        } else {
+                            db.note(&format!("no expected value for `{name}`"));
+                        }
                     }
 
                     // Suggest the most probable if we found one
                     if let Some(best_match) = find_best_match_for_name(&possibilities, value.unwrap_or(name), None) {
-                        let ponctuation = if value.is_some() { "\"" } else { "" };
-                        db.span_suggestion(span, "did you mean", format!("{ponctuation}{best_match}{ponctuation}"), Applicability::MaybeIncorrect);
+                        let punctuation = if value.is_some() { "\"" } else { "" };
+                        db.span_suggestion(span, "did you mean", format!("{punctuation}{best_match}{punctuation}"), Applicability::MaybeIncorrect);
                     }
                 },
             }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index e0a3cc78b17..f9b75690e37 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1023,10 +1023,10 @@ pub fn to_crate_config(cfg: FxHashSet<(String, Option<String>)>) -> CrateConfig
 
 /// The parsed `--check-cfg` options
 pub struct CheckCfg<T = String> {
-    /// The set of all `names()`, if none no names checking is performed
+    /// The set of all `names()`, if None no name checking is performed
     pub names_valid: Option<FxHashSet<T>>,
-    /// The set of all `values()`, if none no values chcking is performed
-    pub values_valid: Option<FxHashMap<T, FxHashSet<T>>>,
+    /// The set of all `values()`
+    pub values_valid: FxHashMap<T, FxHashSet<T>>,
 }
 
 impl<T> Default for CheckCfg<T> {
@@ -1042,9 +1042,11 @@ impl<T> CheckCfg<T> {
                 .names_valid
                 .as_ref()
                 .map(|names_valid| names_valid.iter().map(|a| f(a)).collect()),
-            values_valid: self.values_valid.as_ref().map(|values_valid| {
-                values_valid.iter().map(|(a, b)| (f(a), b.iter().map(|b| f(b)).collect())).collect()
-            }),
+            values_valid: self
+                .values_valid
+                .iter()
+                .map(|(a, b)| (f(a), b.iter().map(|b| f(b)).collect()))
+                .collect(),
         }
     }
 }
@@ -1098,11 +1100,9 @@ impl CrateCheckConfig {
                 names_valid.insert(k);
             }
             if let Some(v) = v {
-                if let Some(values_valid) = &mut self.values_valid {
-                    values_valid.entry(k).and_modify(|values| {
-                        values.insert(v);
-                    });
-                }
+                self.values_valid.entry(k).and_modify(|values| {
+                    values.insert(v);
+                });
             }
         }
     }