Rewrite the untranslatable_diagnostic lint.

Currently it only checks calls to functions marked with `#[rustc_lint_diagnostics]`. This commit changes it to check calls to any function with an `impl Into<{D,Subd}iagMessage>` parameter. This greatly improves its coverage and doesn't rely on people remembering to add `#[rustc_lint_diagnostics]`. The commit also adds `#[allow(rustc::untranslatable_diagnostic)`] attributes to places that need it that are caught by the improved lint. These places that might be easy to convert to translatable diagnostics. Finally, it also: - Expands and corrects some comments. - Does some minor formatting improvements. - Adds missing `DecorateLint` cases to `tests/ui-fulldeps/internal-lints/diagnostics.rs`.
2024-11-22 06:44:35 +00:00 · 2024-02-20 14:12:50 +11:00 · 2024-02-20 14:12:50 +11:00 · b7d58eef4b
commit b7d58eef4b
parent d602394827
35 changed files with 224 additions and 63 deletions
--- a/compiler/rustc_ast_lowering/src/asm.rs
+++ b/compiler/rustc_ast_lowering/src/asm.rs
@ -22,6 +22,7 @@ use std::collections::hash_map::Entry;
 use std::fmt::Write;

 impl<'a, 'hir> LoweringContext<'a, 'hir> {
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    pub(crate) fn lower_inline_asm(
        &mut self,
        sp: Span,
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@ -1495,6 +1495,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
        }
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
        let is_async_gen = match self.coroutine_kind {
            Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)) => false,
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@ -2272,6 +2272,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
        self.expr_block(block)
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn lower_array_length(&mut self, c: &AnonConst) -> hir::ArrayLen {
        match c.value.kind {
            ExprKind::Underscore => {
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@ -17,6 +17,7 @@ use crate::errors;
 macro_rules! gate {
    ($visitor:expr, $feature:ident, $span:expr, $explain:expr) => {{
        if !$visitor.features.$feature && !$span.allows_unstable(sym::$feature) {
+            #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
            feature_err(&$visitor.sess, sym::$feature, $span, $explain).emit();
        }
    }};
@ -34,6 +35,7 @@ macro_rules! gate {
 macro_rules! gate_alt {
    ($visitor:expr, $has_feature:expr, $name:expr, $span:expr, $explain:expr) => {{
        if !$has_feature && !$span.allows_unstable($name) {
+            #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
            feature_err(&$visitor.sess, $name, $span, $explain).emit();
        }
    }};
@ -73,6 +75,7 @@ struct PostExpansionVisitor<'a> {
 }

 impl<'a> PostExpansionVisitor<'a> {
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn check_abi(&self, abi: ast::StrLit, constness: ast::Const) {
        let ast::StrLit { symbol_unescaped, span, .. } = abi;

@ -579,6 +582,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
                if let Ok(snippet) = sm.span_to_snippet(span)
                    && snippet == "!"
                {
+                    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
                    feature_err(sess, sym::never_patterns, span, "`!` patterns are experimental")
                        .emit();
                } else {
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@ -516,6 +516,7 @@ pub struct Condition {
 }

 /// Tests if a cfg-pattern matches the cfg set
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn cfg_matches(
    cfg: &ast::MetaItem,
    sess: &Session,
@ -566,6 +567,7 @@ fn try_gate_cfg(name: Symbol, span: Span, sess: &Session, features: Option<&Feat
    }
 }

+#[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) {
@ -592,6 +594,7 @@ fn parse_version(s: Symbol) -> Option<RustcVersion> {

 /// Evaluate a cfg-like condition (with `any` and `all`), using `eval` to
 /// evaluate individual items.
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn eval_condition(
    cfg: &ast::MetaItem,
    sess: &Session,
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@ -1008,6 +1008,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
        self.borrow_spans(span, borrow.reserve_location)
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn explain_captures(
        &mut self,
        err: &mut Diag<'_>,
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@ -201,6 +201,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
    // For generic associated types (GATs) which implied 'static requirement
    // from higher-ranked trait bounds (HRTB). Try to locate span of the trait
    // and the span which bounded to the trait for adding 'static lifetime suggestion
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn suggest_static_lifetime_for_gat_from_hrtb(
        &self,
        diag: &mut Diag<'_>,
@ -822,6 +823,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
    /// LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + 'a {
    ///    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    /// ```
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn add_static_impl_trait_suggestion(
        &self,
        diag: &mut Diag<'_>,
@ -972,6 +974,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
        self.suggest_constrain_dyn_trait_in_impl(diag, &visitor.0, ident, self_ty);
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    #[instrument(skip(self, err), level = "debug")]
    fn suggest_constrain_dyn_trait_in_impl(
        &self,
@ -1034,6 +1037,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
        suggest_adding_lifetime_params(self.infcx.tcx, sub, ty_sup, ty_sub, diag);
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn suggest_move_on_borrowing_closure(&self, diag: &mut Diag<'_>) {
        let map = self.infcx.tcx.hir();
        let body_id = map.body_owned_by(self.mir_def_id());
--- a/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/ops.rs
@ -62,6 +62,7 @@ impl<'tcx> NonConstOp<'tcx> for FloatingPointOp {
        }
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
        feature_err(
            &ccx.tcx.sess,
@ -556,6 +557,7 @@ impl<'tcx> NonConstOp<'tcx> for RawMutPtrDeref {
        Status::Unstable(sym::const_mut_refs)
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
        feature_err(
            &ccx.tcx.sess,
@ -589,6 +591,7 @@ impl<'tcx> NonConstOp<'tcx> for StaticAccess {
        }
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
        let mut err = feature_err(
            &ccx.tcx.sess,
@ -632,6 +635,7 @@ pub mod ty {
            }
        }

+        #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
        fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
            feature_err(
                &ccx.tcx.sess,
--- a/compiler/rustc_driver_impl/src/args.rs
+++ b/compiler/rustc_driver_impl/src/args.rs
@ -97,6 +97,7 @@ impl Expander {
 /// **Note:** This function doesn't interpret argument 0 in any special way.
 /// If this function is intended to be used with command line arguments,
 /// `argv[0]` must be removed prior to calling it manually.
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn arg_expand_all(early_dcx: &EarlyDiagCtxt, at_args: &[String]) -> Vec<String> {
    let mut expander = Expander::default();
    for arg in at_args {
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@ -4,6 +4,7 @@
 //!
 //! This API is completely unstable and subject to change.

+#![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@ -1483,6 +1483,8 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) -> bool {
                            };

                            if crate_matches {
+                                // FIXME: make this translatable
+                                #[allow(rustc::untranslatable_diagnostic)]
                                sess.psess.buffer_lint_with_diagnostic(
                                        PROC_MACRO_BACK_COMPAT,
                                        item.ident.span,
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@ -239,6 +239,7 @@ impl<'a> StripUnconfigured<'a> {
    /// Gives a compiler warning when the `cfg_attr` contains no attributes and
    /// is in the original source file. Gives a compiler error if the syntax of
    /// the attribute is incorrect.
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    pub(crate) fn expand_cfg_attr(&self, attr: &Attribute, recursive: bool) -> Vec<Attribute> {
        let Some((cfg_predicate, expanded_attrs)) =
            rustc_parse::parse_cfg_attr(attr, &self.sess.psess)
@ -273,6 +274,7 @@ impl<'a> StripUnconfigured<'a> {
        }
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn expand_cfg_attr_item(
        &self,
        attr: &Attribute,
@ -371,6 +373,7 @@ impl<'a> StripUnconfigured<'a> {
    }

    /// If attributes are not allowed on expressions, emit an error for `attr`
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    #[instrument(level = "trace", skip(self))]
    pub(crate) fn maybe_emit_expr_attr_err(&self, attr: &Attribute) {
        if self.features.is_some_and(|features| !features.stmt_expr_attributes)
@ -384,7 +387,6 @@ impl<'a> StripUnconfigured<'a> {
            );

            if attr.is_doc_comment() {
-                #[allow(rustc::untranslatable_diagnostic)]
                err.help("`///` is for documentation comments. For a plain comment, use `//`.");
            }

--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@ -784,6 +784,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
        })
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
        let kind = match item {
            Annotatable::Item(_)
@ -826,6 +827,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
        }

        impl<'ast, 'a> Visitor<'ast> for GateProcMacroInput<'a> {
+            #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
            fn visit_item(&mut self, item: &'ast ast::Item) {
                match &item.kind {
                    ItemKind::Mod(_, mod_kind)
@ -1690,6 +1692,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {

    // Detect use of feature-gated or invalid attributes on macro invocations
    // since they will not be detected after macro expansion.
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn check_attributes(&self, attrs: &[ast::Attribute], call: &ast::MacCall) {
        let features = self.cx.ecfg.features;
        let mut attrs = attrs.iter().peekable();
--- a/compiler/rustc_expand/src/lib.rs
+++ b/compiler/rustc_expand/src/lib.rs
@ -5,6 +5,7 @@
 #![feature(associated_type_defaults)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
+#![feature(lint_reasons)]
 #![feature(macro_metavar_expr)]
 #![feature(map_try_insert)]
 #![feature(proc_macro_diagnostic)]
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@ -517,6 +517,9 @@ impl server::FreeFunctions for Rustc<'_, '_> {
            Diag::new(&self.psess().dcx, diagnostic.level.to_internal(), message);
        diag.span(MultiSpan::from_spans(diagnostic.spans));
        for child in diagnostic.children {
+            // This message comes from another diagnostic, and we are just reconstructing the
+            // diagnostic, so there's no need for translation.
+            #[allow(rustc::untranslatable_diagnostic)]
            diag.sub(child.level.to_internal(), child.message, MultiSpan::from_spans(child.spans));
        }
        diag.emit();
--- a/compiler/rustc_expand/src/tests.rs
+++ b/compiler/rustc_expand/src/tests.rs
@ -178,6 +178,7 @@ impl<T: Write> Write for Shared<T> {
    }
 }

+#[allow(rustc::untranslatable_diagnostic)] // no translation needed for tests
 fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &str) {
    create_default_session_globals_then(|| {
        let (handler, source_map, output) = create_test_handler();
@ -192,7 +193,6 @@ fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &
            println!("text: {:?}", source_map.span_to_snippet(span));
        }

-        #[allow(rustc::untranslatable_diagnostic)]
        handler.span_err(msp, "foo");

        assert!(
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@ -695,8 +695,8 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
    // Used by the `rustc::potential_query_instability` lint to warn methods which
    // might not be stable during incremental compilation.
    rustc_attr!(rustc_lint_query_instability, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
-    // Used by the `rustc::untranslatable_diagnostic` and `rustc::diagnostic_outside_of_impl` lints
-    // to assist in changes to diagnostic APIs.
+    // Used by the `rustc::diagnostic_outside_of_impl` lints to assist in changes to diagnostic
+    // APIs. Any function with this attribute will be checked by that lint.
    rustc_attr!(rustc_lint_diagnostics, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
    // Used by the `rustc::bad_opt_access` lint to identify `DebuggingOptions` and `CodegenOptions`
    // types (as well as any others in future).
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@ -318,6 +318,7 @@ pub struct Config {

 // JUSTIFICATION: before session exists, only config
 #[allow(rustc::bad_opt_access)]
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
    trace!("run_compiler");

--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@ -160,6 +160,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
    })
 }

+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 fn load_backend_from_dylib(early_dcx: &EarlyDiagCtxt, path: &Path) -> MakeBackendFn {
    match unsafe { load_symbol_from_dylib::<MakeBackendFn>(path, "__rustc_codegen_backend") } {
        Ok(backend_sym) => backend_sym,
@ -227,6 +228,7 @@ fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
    })
 }

+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 fn get_codegen_sysroot(
    early_dcx: &EarlyDiagCtxt,
    maybe_sysroot: &Option<PathBuf>,
@ -319,6 +321,7 @@ fn get_codegen_sysroot(
    }
 }

+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub(crate) fn check_attr_crate_type(
    sess: &Session,
    attrs: &[ast::Attribute],
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@ -621,12 +621,13 @@ pub trait LintContext {
    /// Note that this function should only be called for [`LintExpectationId`]s
    /// retrieved from the current lint pass. Buffered or manually created ids can
    /// cause ICEs.
-    #[rustc_lint_diagnostics]
    fn fulfill_expectation(&self, expectation: LintExpectationId) {
        // We need to make sure that submitted expectation ids are correctly fulfilled suppressed
        // and stored between compilation sessions. To not manually do these steps, we simply create
-        // a dummy diagnostic and emit is as usual, which will be suppressed and stored like a normal
-        // expected lint diagnostic.
+        // a dummy diagnostic and emit it as usual, which will be suppressed and stored like a
+        // normal expected lint diagnostic.
+        #[allow(rustc::diagnostic_outside_of_impl)]
+        #[allow(rustc::untranslatable_diagnostic)]
        self.sess()
            .dcx()
            .struct_expect(
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@ -10,7 +10,7 @@ use rustc_ast as ast;
 use rustc_hir::def::Res;
 use rustc_hir::{def_id::DefId, Expr, ExprKind, GenericArg, PatKind, Path, PathSegment, QPath};
 use rustc_hir::{BinOp, BinOpKind, HirId, Impl, Item, ItemKind, Node, Pat, Ty, TyKind};
-use rustc_middle::ty;
+use rustc_middle::ty::{self, Ty as MiddleTy};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::symbol::{kw, sym, Symbol};
@ -338,10 +338,11 @@ impl<'tcx> LateLintPass<'tcx> for ExistingDocKeyword {
 }

 declare_tool_lint! {
-    /// The `untranslatable_diagnostic` lint detects diagnostics created
-    /// without using translatable Fluent strings.
+    /// The `untranslatable_diagnostic` lint detects messages passed to functions with `impl
+    /// Into<{D,Subd}iagMessage` parameters without using translatable Fluent strings.
    ///
-    /// More details on translatable diagnostics can be found [here](https://rustc-dev-guide.rust-lang.org/diagnostics/translation.html).
+    /// More details on translatable diagnostics can be found
+    /// [here](https://rustc-dev-guide.rust-lang.org/diagnostics/translation.html).
    pub rustc::UNTRANSLATABLE_DIAGNOSTIC,
    Deny,
    "prevent creation of diagnostics which cannot be translated",
@ -349,11 +350,13 @@ declare_tool_lint! {
 }

 declare_tool_lint! {
-    /// The `diagnostic_outside_of_impl` lint detects diagnostics created manually,
-    /// and inside an `IntoDiagnostic`/`AddToDiagnostic` implementation,
-    /// or a `#[derive(Diagnostic)]`/`#[derive(Subdiagnostic)]` expansion.
+    /// The `diagnostic_outside_of_impl` lint detects calls to functions annotated with
+    /// `#[rustc_lint_diagnostics]` that are outside an `IntoDiagnostic`, `AddToDiagnostic`, or
+    /// `DecorateLint` impl, or a `#[derive(Diagnostic)]`, `#[derive(Subdiagnostic)]`,
+    /// `#[derive(DecorateLint)]` expansion.
    ///
-    /// More details on diagnostics implementations can be found [here](https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-structs.html).
+    /// More details on diagnostics implementations can be found
+    /// [here](https://rustc-dev-guide.rust-lang.org/diagnostics/diagnostic-structs.html).
    pub rustc::DIAGNOSTIC_OUTSIDE_OF_IMPL,
    Deny,
    "prevent creation of diagnostics outside of `IntoDiagnostic`/`AddToDiagnostic` impls",
@ -364,54 +367,130 @@ declare_lint_pass!(Diagnostics => [UNTRANSLATABLE_DIAGNOSTIC, DIAGNOSTIC_OUTSIDE

 impl LateLintPass<'_> for Diagnostics {
    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-        let Some((span, def_id, args)) = typeck_results_of_method_fn(cx, expr) else { return };
-        debug!(?span, ?def_id, ?args);
-        let has_attr = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, args)
+        // Only check function calls and method calls.
+        let (span, def_id, fn_gen_args, call_tys) = match expr.kind {
+            ExprKind::Call(callee, args) => {
+                match cx.typeck_results().node_type(callee.hir_id).kind() {
+                    &ty::FnDef(def_id, fn_gen_args) => {
+                        let call_tys: Vec<_> =
+                            args.iter().map(|arg| cx.typeck_results().expr_ty(arg)).collect();
+                        (callee.span, def_id, fn_gen_args, call_tys)
+                    }
+                    _ => return, // occurs for fns passed as args
+                }
+            }
+            ExprKind::MethodCall(segment, _recv, args, _span) => {
+                let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
+                let fn_gen_args = cx.typeck_results().node_args(expr.hir_id);
+                let mut call_tys: Vec<_> =
+                    args.iter().map(|arg| cx.typeck_results().expr_ty(arg)).collect();
+                call_tys.insert(0, cx.tcx.types.self_param); // dummy inserted for `self`
+                (segment.ident.span, def_id, fn_gen_args, call_tys)
+            }
+            _ => return,
+        };
+
+        // Is the callee marked with `#[rustc_lint_diagnostics]`?
+        let has_attr = ty::Instance::resolve(cx.tcx, cx.param_env, def_id, fn_gen_args)
            .ok()
            .flatten()
            .is_some_and(|inst| cx.tcx.has_attr(inst.def_id(), sym::rustc_lint_diagnostics));
-        if !has_attr {
-            return;
-        }

-        let mut found_parent_with_attr = false;
-        let mut found_impl = false;
-        for (hir_id, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
-            if let Some(owner_did) = hir_id.as_owner() {
-                found_parent_with_attr = found_parent_with_attr
-                    || cx.tcx.has_attr(owner_did, sym::rustc_lint_diagnostics);
-            }
-
-            debug!(?parent);
-            if let Node::Item(Item { kind: ItemKind::Impl(impl_), .. }) = parent
-                && let Impl { of_trait: Some(of_trait), .. } = impl_
-                && let Some(def_id) = of_trait.trait_def_id()
-                && let Some(name) = cx.tcx.get_diagnostic_name(def_id)
-                && matches!(name, sym::IntoDiagnostic | sym::AddToDiagnostic | sym::DecorateLint)
-            {
-                found_impl = true;
-                break;
-            }
-        }
-        debug!(?found_impl);
-        if !found_parent_with_attr && !found_impl {
-            cx.emit_span_lint(DIAGNOSTIC_OUTSIDE_OF_IMPL, span, DiagOutOfImpl);
-        }
-
-        let mut found_diagnostic_message = false;
-        for ty in args.types() {
-            debug!(?ty);
+        // Closure: is the type `{D,Subd}iagMessage`?
+        let is_diag_message = |ty: MiddleTy<'_>| {
            if let Some(adt_def) = ty.ty_adt_def()
                && let Some(name) = cx.tcx.get_diagnostic_name(adt_def.did())
                && matches!(name, sym::DiagMessage | sym::SubdiagMessage)
            {
-                found_diagnostic_message = true;
+                true
+            } else {
+                false
+            }
+        };
+
+        // Does the callee have a `impl Into<{D,Subd}iagMessage>` parameter? (There should be at
+        // most one.)
+        let mut impl_into_diagnostic_message_param = None;
+        let fn_sig = cx.tcx.fn_sig(def_id).instantiate_identity().skip_binder();
+        let predicates = cx.tcx.predicates_of(def_id).instantiate_identity(cx.tcx).predicates;
+        for (i, &param_ty) in fn_sig.inputs().iter().enumerate() {
+            if let ty::Param(p) = param_ty.kind() {
+                // It is a type parameter. Check if it is `impl Into<{D,Subd}iagMessage>`.
+                for pred in predicates.iter() {
+                    if let Some(trait_pred) = pred.as_trait_clause()
+                        && let trait_ref = trait_pred.skip_binder().trait_ref
+                        && trait_ref.self_ty() == param_ty // correct predicate for the param?
+                        && cx.tcx.is_diagnostic_item(sym::Into, trait_ref.def_id)
+                        && let ty1 = trait_ref.args.type_at(1)
+                        && is_diag_message(ty1)
+                    {
+                        if impl_into_diagnostic_message_param.is_some() {
+                            cx.tcx.dcx().span_bug(
+                                span,
+                                "can't handle multiple `impl Into<{D,Sub}iagMessage>` params",
+                            );
+                        }
+                        impl_into_diagnostic_message_param = Some((i, p.name));
+                    }
+                }
+            }
+        }
+
+        // Is the callee interesting?
+        if !has_attr && impl_into_diagnostic_message_param.is_none() {
+            return;
+        }
+
+        // Is the parent method marked with `#[rustc_lint_diagnostics]`?
+        let mut parent_has_attr = false;
+        for (hir_id, _parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
+            if let Some(owner_did) = hir_id.as_owner()
+                && cx.tcx.has_attr(owner_did, sym::rustc_lint_diagnostics)
+            {
+                parent_has_attr = true;
                break;
            }
        }
-        debug!(?found_diagnostic_message);
-        if !found_parent_with_attr && !found_diagnostic_message {
-            cx.emit_span_lint(UNTRANSLATABLE_DIAGNOSTIC, span, UntranslatableDiag);
+
+        // Calls to `#[rustc_lint_diagnostics]`-marked functions should only occur:
+        // - inside an impl of `IntoDiagnostic`, `AddToDiagnostic`, or `DecorateLint`, or
+        // - inside a parent function that is itself marked with `#[rustc_lint_diagnostics]`.
+        //
+        // Otherwise, emit a `DIAGNOSTIC_OUTSIDE_OF_IMPL` lint.
+        if has_attr && !parent_has_attr {
+            let mut is_inside_appropriate_impl = false;
+            for (_hir_id, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
+                debug!(?parent);
+                if let Node::Item(Item { kind: ItemKind::Impl(impl_), .. }) = parent
+                    && let Impl { of_trait: Some(of_trait), .. } = impl_
+                    && let Some(def_id) = of_trait.trait_def_id()
+                    && let Some(name) = cx.tcx.get_diagnostic_name(def_id)
+                    && matches!(
+                        name,
+                        sym::IntoDiagnostic | sym::AddToDiagnostic | sym::DecorateLint
+                    )
+                {
+                    is_inside_appropriate_impl = true;
+                    break;
+                }
+            }
+            debug!(?is_inside_appropriate_impl);
+            if !is_inside_appropriate_impl {
+                cx.emit_span_lint(DIAGNOSTIC_OUTSIDE_OF_IMPL, span, DiagOutOfImpl);
+            }
+        }
+
+        // Calls to methods with an `impl Into<{D,Subd}iagMessage>` parameter must be passed an arg
+        // with type `{D,Subd}iagMessage` or `impl Into<{D,Subd}iagMessage>`. Otherwise, emit an
+        // `UNTRANSLATABLE_DIAGNOSTIC` lint.
+        if let Some((param_i, param_i_p_name)) = impl_into_diagnostic_message_param {
+            // Is the arg type `{Sub,D}iagMessage`or `impl Into<{Sub,D}iagMessage>`?
+            let arg_ty = call_tys[param_i];
+            let is_translatable = is_diag_message(arg_ty)
+                || matches!(arg_ty.kind(), ty::Param(p) if p.name == param_i_p_name);
+            if !is_translatable {
+                cx.emit_span_lint(UNTRANSLATABLE_DIAGNOSTIC, span, UntranslatableDiag);
+            }
        }
    }
 }
@ -425,7 +504,7 @@ declare_tool_lint! {
    report_in_external_macro: true
 }

-declare_lint_pass!(BadOptAccess => [ BAD_OPT_ACCESS ]);
+declare_lint_pass!(BadOptAccess => [BAD_OPT_ACCESS]);

 impl LateLintPass<'_> for BadOptAccess {
    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
--- a/compiler/rustc_lint/src/let_underscore.rs
+++ b/compiler/rustc_lint/src/let_underscore.rs
@ -104,6 +104,7 @@ const SYNC_GUARD_SYMBOLS: [Symbol; 3] = [
 ];

 impl<'tcx> LateLintPass<'tcx> for LetUnderscore {
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn check_local(&mut self, cx: &LateContext<'_>, local: &hir::Local<'_>) {
        if matches!(local.source, rustc_hir::LocalSource::AsyncFn) {
            return;
--- a/compiler/rustc_lint/src/levels.rs
+++ b/compiler/rustc_lint/src/levels.rs
@ -724,6 +724,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
        };
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn add(&mut self, attrs: &[ast::Attribute], is_crate_node: bool, source_hir_id: Option<HirId>) {
        let sess = self.sess;
        for (attr_index, attr) in attrs.iter().enumerate() {
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@ -947,6 +947,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
        }
    }

+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn report_unused_deps(&mut self, krate: &ast::Crate) {
        // Make a point span rather than covering the whole file
        let span = krate.spans.inner_span.shrink_to_lo();
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@ -93,6 +93,7 @@ struct Collector<'tcx> {
 }

 impl<'tcx> Collector<'tcx> {
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn process_module(&mut self, module: &ForeignModule) {
        let ForeignModule { def_id, abi, ref foreign_items } = *module;
        let def_id = def_id.expect_local();
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@ -1074,6 +1074,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
    /// of one item. Read the documentation of [`check_doc_inline`] for more information.
    ///
    /// [`check_doc_inline`]: Self::check_doc_inline
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn check_doc_attrs(
        &self,
        attr: &Attribute,
@ -1756,6 +1757,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
    }

    /// Checks if the `#[repr]` attributes on `item` are valid.
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn check_repr(
        &self,
        attrs: &[Attribute],
--- a/compiler/rustc_passes/src/check_const.rs
+++ b/compiler/rustc_passes/src/check_const.rs
@ -77,6 +77,7 @@ impl<'tcx> CheckConstVisitor<'tcx> {
    }

    /// Emits an error when an unsupported expression is found in a const context.
+    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
    fn const_check_violated(&self, expr: NonConstExpr, span: Span) {
        let Self { tcx, def_id, const_kind } = *self;

--- a/compiler/rustc_passes/src/entry.rs
+++ b/compiler/rustc_passes/src/entry.rs
@ -114,6 +114,7 @@ fn find_item(id: ItemId, ctxt: &mut EntryContext<'_>) {
    }
 }

+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 fn configure_main(tcx: TyCtxt<'_>, visitor: &EntryContext<'_>) -> Option<(DefId, EntryFnType)> {
    if let Some((def_id, _)) = visitor.start_fn {
        Some((def_id.to_def_id(), EntryFnType::Start))
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@ -1,6 +1,8 @@
 //! Contains infrastructure for configuring the compiler, including parsing
 //! command-line options.

+#![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+
 pub use crate::options::*;

 use crate::errors::FileWriteFail;
@ -2468,9 +2470,7 @@ pub fn parse_externs(
            ));
            let adjusted_name = name.replace('-', "_");
            if is_ascii_ident(&adjusted_name) {
-                // FIXME: make this translatable
-                #[allow(rustc::diagnostic_outside_of_impl)]
-                #[allow(rustc::untranslatable_diagnostic)]
+                #[allow(rustc::diagnostic_outside_of_impl)] // FIXME
                error.help(format!(
                    "consider replacing the dashes with underscores: `{adjusted_name}`"
                ));
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@ -320,6 +320,7 @@ macro_rules! redirect_field {
 type OptionSetter<O> = fn(&mut O, v: Option<&str>) -> bool;
 type OptionDescrs<O> = &'static [(&'static str, OptionSetter<O>, &'static str, &'static str)];

+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 fn build_options<O: Default>(
    early_dcx: &EarlyDiagCtxt,
    matches: &getopts::Matches,
--- a/compiler/rustc_session/src/search_paths.rs
+++ b/compiler/rustc_session/src/search_paths.rs
@ -61,6 +61,7 @@ impl SearchPath {
            (PathKind::All, path)
        };
        if path.is_empty() {
+            #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
            early_dcx.early_fatal("empty search path given via `-L`");
        }

--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@ -1022,6 +1022,7 @@ fn default_emitter(

 // JUSTIFICATION: literally session construction
 #[allow(rustc::bad_opt_access)]
+#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn build_session(
    early_dcx: EarlyDiagCtxt,
    sopts: config::Options,
--- a/src/tools/rustfmt/src/parse/session.rs
+++ b/src/tools/rustfmt/src/parse/session.rs
@ -383,6 +383,7 @@ mod tests {
        }

        fn build_diagnostic(level: DiagnosticLevel, span: Option<MultiSpan>) -> DiagInner {
+            #[allow(rustc::untranslatable_diagnostic)] // no translation needed for empty string
            let mut diag = DiagInner::new(level, "");
            diag.messages.clear();
            if let Some(span) = span {
--- a/tests/ui-fulldeps/internal-lints/diagnostics.rs
+++ b/tests/ui-fulldeps/internal-lints/diagnostics.rs
@ -14,8 +14,8 @@ extern crate rustc_session;
 extern crate rustc_span;

 use rustc_errors::{
-    AddToDiagnostic, Diag, EmissionGuarantee, DiagCtxt, IntoDiagnostic, Level,
-    SubdiagMessageOp,
+    AddToDiagnostic, DecorateLint, Diag, DiagCtxt, DiagInner, DiagMessage, EmissionGuarantee,
+    IntoDiagnostic, Level, SubdiagMessageOp,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::Span;
@ -78,6 +78,31 @@ impl AddToDiagnostic for TranslatableInAddToDiagnostic {
    }
 }

+pub struct UntranslatableInDecorateLint;
+
+impl<'a> DecorateLint<'a, ()> for UntranslatableInDecorateLint {
+    fn decorate_lint<'b, >(self, diag: &'b mut Diag<'a, ()>) {
+        diag.note("untranslatable diagnostic");
+        //~^ ERROR diagnostics should be created using translatable messages
+    }
+
+    fn msg(&self) -> DiagMessage {
+        unreachable!();
+    }
+}
+
+pub struct TranslatableInDecorateLint;
+
+impl<'a> DecorateLint<'a, ()> for TranslatableInDecorateLint {
+    fn decorate_lint<'b>(self, diag: &'b mut Diag<'a, ()>) {
+        diag.note(crate::fluent_generated::no_crate_note);
+    }
+
+    fn msg(&self) -> DiagMessage {
+        unreachable!();
+    }
+}
+
 pub fn make_diagnostics<'a>(dcx: &'a DiagCtxt) {
    let _diag = dcx.struct_err(crate::fluent_generated::no_crate_example);
    //~^ ERROR diagnostics should only be created in `IntoDiagnostic`/`AddToDiagnostic` impls
@ -87,9 +112,11 @@ pub fn make_diagnostics<'a>(dcx: &'a DiagCtxt) {
    //~^^ ERROR diagnostics should be created using translatable messages
 }

-// Check that `rustc_lint_diagnostics`-annotated functions aren't themselves linted.
+// Check that `rustc_lint_diagnostics`-annotated functions aren't themselves linted for
+// `diagnostic_outside_of_impl`.

 #[rustc_lint_diagnostics]
 pub fn skipped_because_of_annotation<'a>(dcx: &'a DiagCtxt) {
+    #[allow(rustc::untranslatable_diagnostic)]
    let _diag = dcx.struct_err("untranslatable diagnostic"); // okay!
 }
--- a/tests/ui-fulldeps/internal-lints/diagnostics.stderr
+++ b/tests/ui-fulldeps/internal-lints/diagnostics.stderr
@ -16,8 +16,14 @@ error: diagnostics should be created using translatable messages
 LL |         diag.note("untranslatable diagnostic");
   |              ^^^^

+error: diagnostics should be created using translatable messages
+  --> $DIR/diagnostics.rs:85:14
+   |
+LL |         diag.note("untranslatable diagnostic");
+   |              ^^^^
+
 error: diagnostics should only be created in `IntoDiagnostic`/`AddToDiagnostic` impls
-  --> $DIR/diagnostics.rs:82:21
+  --> $DIR/diagnostics.rs:107:21
   |
 LL |     let _diag = dcx.struct_err(crate::fluent_generated::no_crate_example);
   |                     ^^^^^^^^^^
@ -29,16 +35,16 @@ LL | #![deny(rustc::diagnostic_outside_of_impl)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 error: diagnostics should only be created in `IntoDiagnostic`/`AddToDiagnostic` impls
-  --> $DIR/diagnostics.rs:85:21
+  --> $DIR/diagnostics.rs:110:21
   |
 LL |     let _diag = dcx.struct_err("untranslatable diagnostic");
   |                     ^^^^^^^^^^

 error: diagnostics should be created using translatable messages
-  --> $DIR/diagnostics.rs:85:21
+  --> $DIR/diagnostics.rs:110:21
   |
 LL |     let _diag = dcx.struct_err("untranslatable diagnostic");
   |                     ^^^^^^^^^^

-error: aborting due to 5 previous errors
+error: aborting due to 6 previous errors