errors: lint on LintDiagnosticBuilder::build

Apply the `#[rustc_lint_diagnostics]` attribute to
`LintDiagnosticBuilder::build` so that diagnostic migration lints will
trigger for it.

Signed-off-by: David Wood <david.wood@huawei.com>

Author: davidtwco

compiler/rustc_error_messages/locales/en-US/privacy.ftl

@@ -10,3 +10,12 @@ privacy-unnamed-item-is-private = {$kind} is private
 privacy-in-public-interface = {$vis_descr} {$kind} `{$descr}` in public interface
     .label = can't leak {$vis_descr} {$kind}
     .visibility-label = `{$descr}` declared as {$vis_descr}
+
+privacy-from-private-dep-in-public-interface =
+    {$kind} `{$descr}` from private dependency '{$krate}' in public interface
+
+private-in-public-lint =
+    {$vis_descr} {$kind} `{$descr}` in public interface (error {$kind ->
+        [trait] E0445
+        *[other] E0446
+    })

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -595,6 +595,7 @@ macro_rules! error_code {
 pub struct LintDiagnosticBuilder<'a, G: EmissionGuarantee>(DiagnosticBuilder<'a, G>);
 
 impl<'a, G: EmissionGuarantee> LintDiagnosticBuilder<'a, G> {
+    #[rustc_lint_diagnostics]
     /// Return the inner `DiagnosticBuilder`, first setting the primary message to `msg`.
     pub fn build(mut self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'a, G> {
         self.0.set_primary_message(msg);

compiler/rustc_privacy/src/errors.rs

@@ -1,4 +1,4 @@
-use rustc_macros::{SessionDiagnostic, SessionSubdiagnostic};
+use rustc_macros::{LintDiagnostic, SessionDiagnostic, SessionSubdiagnostic};
 use rustc_span::{Span, Symbol};
 
 #[derive(SessionDiagnostic)]
@@ -73,3 +73,19 @@ pub struct InPublicInterface<'a> {
     #[label(privacy::visibility_label)]
     pub vis_span: Span,
 }
+
+#[derive(LintDiagnostic)]
+#[lint(privacy::from_private_dep_in_public_interface)]
+pub struct FromPrivateDependencyInPublicInterface<'a> {
+    pub kind: &'a str,
+    pub descr: String,
+    pub krate: Symbol,
+}
+
+#[derive(LintDiagnostic)]
+#[lint(privacy::private_in_public_lint)]
+pub struct PrivateInPublicLint<'a> {
+    pub vis_descr: &'static str,
+    pub kind: &'a str,
+    pub descr: String,
+}

compiler/rustc_privacy/src/lib.rs

@@ -38,8 +38,8 @@ use std::ops::ControlFlow;
 use std::{cmp, fmt, mem};
 
 use errors::{
-    FieldIsPrivate, FieldIsPrivateLabel, InPublicInterface, InPublicInterfaceTraits, ItemIsPrivate,
-    UnnamedItemIsPrivate,
+    FieldIsPrivate, FieldIsPrivateLabel, FromPrivateDependencyInPublicInterface, InPublicInterface,
+    InPublicInterfaceTraits, ItemIsPrivate, PrivateInPublicLint, UnnamedItemIsPrivate,
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1716,19 +1716,14 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
 
     fn check_def_id(&mut self, def_id: DefId, kind: &str, descr: &dyn fmt::Display) -> bool {
         if self.leaks_private_dep(def_id) {
-            self.tcx.struct_span_lint_hir(
+            self.tcx.emit_spanned_lint(
                 lint::builtin::EXPORTED_PRIVATE_DEPENDENCIES,
                 self.tcx.hir().local_def_id_to_hir_id(self.item_def_id),
                 self.tcx.def_span(self.item_def_id.to_def_id()),
-                |lint| {
-                    lint.build(&format!(
-                        "{} `{}` from private dependency '{}' in public \
-                                                interface",
-                        kind,
-                        descr,
-                        self.tcx.crate_name(def_id.krate)
-                    ))
-                    .emit();
+                FromPrivateDependencyInPublicInterface {
+                    kind,
+                    descr: descr.to_string(),
+                    krate: self.tcx.crate_name(def_id.krate),
                 },
             );
         }
@@ -1754,12 +1749,14 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                 }
             };
             let span = self.tcx.def_span(self.item_def_id.to_def_id());
+            let descr = descr.to_string();
             if self.has_old_errors
                 || self.in_assoc_ty
                 || self.tcx.resolutions(()).has_pub_restricted
             {
                 let descr = descr.to_string();
-                let vis_span = self.tcx.def_span(def_id);
+                let vis_span =
+                    self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id));
                 if kind == "trait" {
                     self.tcx.sess.emit_err(InPublicInterfaceTraits {
                         span,
@@ -1778,19 +1775,11 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                     });
                 }
             } else {
-                let err_code = if kind == "trait" { "E0445" } else { "E0446" };
-                self.tcx.struct_span_lint_hir(
+                self.tcx.emit_spanned_lint(
                     lint::builtin::PRIVATE_IN_PUBLIC,
                     hir_id,
                     span,
-                    |lint| {
-                        lint.build(&format!(
-                            "{} (error {})",
-                            format!("{} {} `{}` in public interface", vis_descr, kind, descr),
-                            err_code
-                        ))
-                        .emit();
-                    },
+                    PrivateInPublicLint { vis_descr, kind, descr },
                 );
             }
         }