Add information about group a lint belongs to

compiler/rustc_lint/src/context.rs

@@ -61,7 +61,13 @@ pub struct LintStore {
     lint_groups: FxIndexMap<&'static str, LintGroup>,
 }
 
-impl LintStoreMarker for LintStore {}
+impl LintStoreMarker for LintStore {
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = rustc_session::LintGroup> + '_> {
+        Box::new(self.get_lint_groups().map(|(name, lints, is_externally_loaded)| {
+            rustc_session::LintGroup { name, lints, is_externally_loaded }
+        }))
+    }
+}
 
 /// The target of the `by_name` map, which accounts for renaming/deprecation.
 #[derive(Debug)]

compiler/rustc_middle/src/lint.rs

@@ -211,11 +211,34 @@ impl LintExpectation {
 }
 
 fn explain_lint_level_source(
+    sess: &Session,
     lint: &'static Lint,
     level: Level,
     src: LintLevelSource,
     err: &mut Diag<'_, ()>,
 ) {
+    /// Find the name of the lint group that contains the given lint.
+    /// Assumes the lint only belongs to one group.
+    fn lint_group_name(
+        lint: &'static Lint,
+        sess: &Session,
+        allow_external: bool,
+    ) -> Option<&'static str> {
+        let mut lint_groups_iter = sess.lint_groups_iter();
+        let lint_id = LintId::of(lint);
+        lint_groups_iter
+            .find(|lint_group| {
+                if !allow_external && lint_group.is_externally_loaded {
+                    return false;
+                }
+                lint_group
+                    .lints
+                    .iter()
+                    .find(|lint_group_lint| **lint_group_lint == lint_id)
+                    .is_some()
+            })
+            .map(|lint_group| lint_group.name)
+    }
     let name = lint.name_lower();
     if let Level::Allow = level {
         // Do not point at `#[allow(compat_lint)]` as the reason for a compatibility lint
@@ -224,7 +247,15 @@ fn explain_lint_level_source(
     }
     match src {
         LintLevelSource::Default => {
-            err.note_once(format!("`#[{}({})]` on by default", level.as_str(), name));
+            let level_str = level.as_str();
+            match lint_group_name(lint, sess, false) {
+                Some(group_name) => {
+                    err.note_once(format!("`#[{level_str}({name})]` (part of `#[{level_str}({group_name})]`) on by default"));
+                }
+                None => {
+                    err.note_once(format!("`#[{level_str}({name})]` on by default"));
+                }
+            }
         }
         LintLevelSource::CommandLine(lint_flag_val, orig_level) => {
             let flag = orig_level.to_cmd_flag();
@@ -428,7 +459,7 @@ pub fn lint_level(
             decorate(&mut err);
         }
 
-        explain_lint_level_source(lint, level, src, &mut err);
+        explain_lint_level_source(sess, lint, level, src, &mut err);
         err.emit()
     }
     lint_level_impl(sess, lint, level, span, Box::new(decorate))

compiler/rustc_session/src/session.rs

@@ -42,6 +42,7 @@ use crate::config::{
     SwitchWithOptPath,
 };
 use crate::filesearch::FileSearch;
+use crate::lint::LintId;
 use crate::parse::{ParseSess, add_feature_diagnostics};
 use crate::search_paths::SearchPath;
 use crate::{errors, filesearch, lint};
@@ -137,7 +138,10 @@ pub struct CompilerIO {
     pub temps_dir: Option<PathBuf>,
 }
 
-pub trait LintStoreMarker: Any + DynSync + DynSend {}
+pub trait LintStoreMarker: Any + DynSync + DynSend {
+    /// Provides a way to access lint groups without depending on `rustc_lint`
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_>;
+}
 
 /// Represents the data associated with a compilation
 /// session for a single crate.
@@ -243,6 +247,12 @@ impl CodegenUnits {
     }
 }
 
+pub struct LintGroup {
+    pub name: &'static str,
+    pub lints: Vec<LintId>,
+    pub is_externally_loaded: bool,
+}
+
 impl Session {
     pub fn miri_unleashed_feature(&self, span: Span, feature_gate: Option<Symbol>) {
         self.miri_unleashed_features.lock().push((span, feature_gate));
@@ -608,6 +618,13 @@ impl Session {
             (&*self.target.staticlib_prefix, &*self.target.staticlib_suffix)
         }
     }
+
+    pub fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_> {
+        match self.lint_store {
+            Some(ref lint_store) => lint_store.lint_groups_iter(),
+            None => Box::new(std::iter::empty()),
+        }
+    }
 }
 
 // JUSTIFICATION: defn of the suggested wrapper fns

src/tools/clippy/tests/ui/checked_unwrap/simple_conditionals.stderr

@@ -244,7 +244,7 @@ LL |         if X.is_some() {
    |
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/static-mut-references.html>
    = note: shared references to mutable statics are dangerous; it's undefined behavior if the static is mutated or if a mutable reference is created for it while the shared reference lives
-   = note: `#[deny(static_mut_refs)]` on by default
+   = note: `#[deny(static_mut_refs)]` (part of `#[deny(rust_2024_compatibility)]`) on by default
 
 error: aborting due to 26 previous errors
 

tests/ui/abi/unsupported.aarch64.stderr

@@ -6,7 +6,7 @@ LL | fn ptx_ptr(f: extern "ptx-kernel" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 error[E0570]: `"ptx-kernel"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:40:1
@@ -215,7 +215,7 @@ LL | fn ptx_ptr(f: extern "ptx-kernel" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "aapcs" is not supported on this target
@@ -226,7 +226,7 @@ LL | fn aapcs_ptr(f: extern "aapcs" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "msp430-interrupt" is not supported on this target
@@ -237,7 +237,7 @@ LL | fn msp430_ptr(f: extern "msp430-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "avr-interrupt" is not supported on this target
@@ -248,7 +248,7 @@ LL | fn avr_ptr(f: extern "avr-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "riscv-interrupt-m" is not supported on this target
@@ -259,7 +259,7 @@ LL | fn riscv_ptr(f: extern "riscv-interrupt-m" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "x86-interrupt" is not supported on this target
@@ -270,7 +270,7 @@ LL | fn x86_ptr(f: extern "x86-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "thiscall" is not supported on this target
@@ -281,7 +281,7 @@ LL | fn thiscall_ptr(f: extern "thiscall" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "stdcall" is not supported on this target
@@ -292,7 +292,7 @@ LL | fn stdcall_ptr(f: extern "stdcall" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "C-cmse-nonsecure-call" is not supported on this target
@@ -303,7 +303,7 @@ LL | fn cmse_call_ptr(f: extern "C-cmse-nonsecure-call" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "C-cmse-nonsecure-entry" is not supported on this target
@@ -314,5 +314,5 @@ LL | fn cmse_entry_ptr(f: extern "C-cmse-nonsecure-entry" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 

tests/ui/abi/unsupported.arm.stderr

@@ -6,7 +6,7 @@ LL | fn ptx_ptr(f: extern "ptx-kernel" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 error[E0570]: `"ptx-kernel"` is not a supported ABI for the current target
   --> $DIR/unsupported.rs:40:1
@@ -194,7 +194,7 @@ LL | fn ptx_ptr(f: extern "ptx-kernel" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "msp430-interrupt" is not supported on this target
@@ -205,7 +205,7 @@ LL | fn msp430_ptr(f: extern "msp430-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "avr-interrupt" is not supported on this target
@@ -216,7 +216,7 @@ LL | fn avr_ptr(f: extern "avr-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "riscv-interrupt-m" is not supported on this target
@@ -227,7 +227,7 @@ LL | fn riscv_ptr(f: extern "riscv-interrupt-m" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "x86-interrupt" is not supported on this target
@@ -238,7 +238,7 @@ LL | fn x86_ptr(f: extern "x86-interrupt" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "thiscall" is not supported on this target
@@ -249,7 +249,7 @@ LL | fn thiscall_ptr(f: extern "thiscall" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "stdcall" is not supported on this target
@@ -260,7 +260,7 @@ LL | fn stdcall_ptr(f: extern "stdcall" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "C-cmse-nonsecure-call" is not supported on this target
@@ -271,7 +271,7 @@ LL | fn cmse_call_ptr(f: extern "C-cmse-nonsecure-call" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default
 
 Future breakage diagnostic:
 warning: the calling convention "C-cmse-nonsecure-entry" is not supported on this target
@@ -282,5 +282,5 @@ LL | fn cmse_entry_ptr(f: extern "C-cmse-nonsecure-entry" fn()) {
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #130260 <https://github.com/rust-lang/rust/issues/130260>
-   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` on by default
+   = note: `#[warn(unsupported_fn_ptr_calling_conventions)]` (part of `#[warn(future_incompatible)]`) on by default