Remove BuiltinLintDiag::UnusedImports variant

compiler/rustc_lint/src/early/diagnostics.rs

@@ -36,31 +36,6 @@ pub struct DecorateBuiltinLint<'sess, 'tcx> {
 impl<'a> Diagnostic<'a, ()> for DecorateBuiltinLint<'_, '_> {
     fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, ()> {
         match self.diagnostic {
-            BuiltinLintDiag::UnusedImports {
-                remove_whole_use,
-                num_to_remove,
-                remove_spans,
-                test_module_span,
-                span_snippets,
-            } => {
-                let sugg = if remove_whole_use {
-                    lints::UnusedImportsSugg::RemoveWholeUse { span: remove_spans[0] }
-                } else {
-                    lints::UnusedImportsSugg::RemoveImports { remove_spans, num_to_remove }
-                };
-                let test_module_span =
-                    test_module_span.map(|span| self.sess.source_map().guess_head_span(span));
-
-                lints::UnusedImports {
-                    sugg,
-                    test_module_span,
-                    num_snippets: span_snippets.len(),
-                    span_snippets: DiagArgValue::StrListSepByAnd(
-                        span_snippets.into_iter().map(Cow::Owned).collect(),
-                    ),
-                }
-                .into_diag(dcx, level)
-            }
             BuiltinLintDiag::NamedArgumentUsedPositionally {
                 position_sp_to_replace,
                 position_sp_for_msg,

compiler/rustc_lint/src/lints.rs

@@ -3039,50 +3039,6 @@ pub(crate) struct IllFormedAttributeInputHelp {
     pub lint: String,
 }
 
-#[derive(Diagnostic)]
-#[diag(
-    "{$num_snippets ->
-        [one] unused import: {$span_snippets}
-        *[other] unused imports: {$span_snippets}
-    }"
-)]
-pub(crate) struct UnusedImports {
-    #[subdiagnostic]
-    pub sugg: UnusedImportsSugg,
-    #[help("if this is a test module, consider adding a `#[cfg(test)]` to the containing module")]
-    pub test_module_span: Option<Span>,
-
-    pub span_snippets: DiagArgValue,
-    pub num_snippets: usize,
-}
-
-#[derive(Subdiagnostic)]
-pub(crate) enum UnusedImportsSugg {
-    #[suggestion(
-        "remove the whole `use` item",
-        applicability = "machine-applicable",
-        code = "",
-        style = "tool-only"
-    )]
-    RemoveWholeUse {
-        #[primary_span]
-        span: Span,
-    },
-    #[multipart_suggestion(
-        "{$num_to_remove ->
-            [one] remove the unused import
-            *[other] remove the unused imports
-        }",
-        applicability = "machine-applicable",
-        style = "tool-only"
-    )]
-    RemoveImports {
-        #[suggestion_part(code = "")]
-        remove_spans: Vec<Span>,
-        num_to_remove: usize,
-    },
-}
-
 #[derive(Diagnostic)]
 #[diag("named argument `{$named_arg_name}` is not used by name")]
 pub(crate) struct NamedArgumentUsedPositionally {

compiler/rustc_lint_defs/src/lib.rs

@@ -656,13 +656,6 @@ pub enum DeprecatedSinceKind {
 // becomes hacky (and it gets allocated).
 #[derive(Debug)]
 pub enum BuiltinLintDiag {
-    UnusedImports {
-        remove_whole_use: bool,
-        num_to_remove: usize,
-        remove_spans: Vec<Span>,
-        test_module_span: Option<Span>,
-        span_snippets: Vec<String>,
-    },
     NamedArgumentUsedPositionally {
         /// Span where the named argument is used by position and will be replaced with the named
         /// argument name

compiler/rustc_resolve/src/check_unused.rs

@@ -23,13 +23,14 @@
 //  - `check_unused` finally emits the diagnostics based on the data generated
 //    in the last step
 
+use std::borrow::Cow;
+
 use rustc_ast as ast;
 use rustc_ast::visit::{self, Visitor};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
 use rustc_data_structures::unord::UnordSet;
-use rustc_errors::MultiSpan;
+use rustc_errors::{DiagArgValue, Diagnostic, MultiSpan};
 use rustc_hir::def::{DefKind, Res};
-use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::{
     MACRO_USE_EXTERN_CRATE, UNUSED_EXTERN_CRATES, UNUSED_IMPORTS, UNUSED_QUALIFICATIONS,
 };
@@ -496,16 +497,32 @@ pub(crate) fn check_unused(&mut self, krate: &ast::Crate) {
                 }
             };
 
-            visitor.r.lint_buffer.buffer_lint(
+            visitor.r.lint_buffer.dyn_buffer_lint_any(
                 UNUSED_IMPORTS,
                 unused.use_tree_id,
                 ms,
-                BuiltinLintDiag::UnusedImports {
-                    remove_whole_use,
-                    num_to_remove,
-                    remove_spans,
-                    test_module_span,
-                    span_snippets,
+                move |dcx, level, sess| {
+                    let sugg = if remove_whole_use {
+                        errors::UnusedImportsSugg::RemoveWholeUse { span: remove_spans[0] }
+                    } else {
+                        errors::UnusedImportsSugg::RemoveImports { remove_spans, num_to_remove }
+                    };
+                    let test_module_span = test_module_span.map(|span| {
+                        sess.downcast_ref::<rustc_session::Session>()
+                            .expect("expected a `Session`")
+                            .source_map()
+                            .guess_head_span(span)
+                    });
+
+                    errors::UnusedImports {
+                        sugg,
+                        test_module_span,
+                        num_snippets: span_snippets.len(),
+                        span_snippets: DiagArgValue::StrListSepByAnd(
+                            span_snippets.into_iter().map(Cow::Owned).collect(),
+                        ),
+                    }
+                    .into_diag(dcx, level)
                 },
             );
         }

compiler/rustc_resolve/src/errors.rs

@@ -1,7 +1,7 @@
 use rustc_errors::codes::*;
 use rustc_errors::formatting::DiagMessageAddArg;
 use rustc_errors::{
-    Applicability, Diag, DiagCtxtHandle, Diagnostic, ElidedLifetimeInPathSubdiag,
+    Applicability, Diag, DiagArgValue, DiagCtxtHandle, Diagnostic, ElidedLifetimeInPathSubdiag,
     EmissionGuarantee, IntoDiagArg, Level, MultiSpan, Subdiagnostic, msg,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
@@ -1747,3 +1747,47 @@ pub(crate) struct ElidedLifetimesInPaths {
     #[subdiagnostic]
     pub subdiag: rustc_errors::ElidedLifetimeInPathSubdiag,
 }
+
+#[derive(Diagnostic)]
+#[diag(
+    "{$num_snippets ->
+        [one] unused import: {$span_snippets}
+        *[other] unused imports: {$span_snippets}
+    }"
+)]
+pub(crate) struct UnusedImports {
+    #[subdiagnostic]
+    pub sugg: UnusedImportsSugg,
+    #[help("if this is a test module, consider adding a `#[cfg(test)]` to the containing module")]
+    pub test_module_span: Option<Span>,
+
+    pub span_snippets: DiagArgValue,
+    pub num_snippets: usize,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum UnusedImportsSugg {
+    #[suggestion(
+        "remove the whole `use` item",
+        applicability = "machine-applicable",
+        code = "",
+        style = "tool-only"
+    )]
+    RemoveWholeUse {
+        #[primary_span]
+        span: Span,
+    },
+    #[multipart_suggestion(
+        "{$num_to_remove ->
+            [one] remove the unused import
+            *[other] remove the unused imports
+        }",
+        applicability = "machine-applicable",
+        style = "tool-only"
+    )]
+    RemoveImports {
+        #[suggestion_part(code = "")]
+        remove_spans: Vec<Span>,
+        num_to_remove: usize,
+    },
+}