Migrate ast_lowering::path to SessionDiagnostic

Cargo.lock

@@ -3575,6 +3575,7 @@ dependencies = [
  "rustc_errors",
  "rustc_hir",
  "rustc_index",
+ "rustc_macros",
  "rustc_middle",
  "rustc_query_system",
  "rustc_session",

compiler/rustc_ast_lowering/Cargo.toml

@@ -15,6 +15,7 @@ rustc_target = { path = "../rustc_target" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_index = { path = "../rustc_index" }
 rustc_middle = { path = "../rustc_middle" }
+rustc_macros = { path = "../rustc_macros" }
 rustc_query_system = { path = "../rustc_query_system" }
 rustc_span = { path = "../rustc_span" }
 rustc_errors = { path = "../rustc_errors" }

compiler/rustc_ast_lowering/src/errors.rs

@@ -0,0 +1,29 @@
+use rustc_errors::{fluent, AddSubdiagnostic, Applicability, Diagnostic};
+use rustc_macros::SessionDiagnostic;
+use rustc_span::Span;
+
+#[derive(SessionDiagnostic, Clone, Copy)]
+#[error(ast_lowering::generic_type_with_parentheses, code = "E0214")]
+pub struct GenericTypeWithParentheses {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[subdiagnostic]
+    pub sub: Option<UseAngleBrackets>,
+}
+
+#[derive(Clone, Copy)]
+pub struct UseAngleBrackets {
+    pub open_param: Span,
+    pub close_param: Span,
+}
+
+impl AddSubdiagnostic for UseAngleBrackets {
+    fn add_to_diagnostic(self, diag: &mut Diagnostic) {
+        diag.multipart_suggestion(
+            fluent::ast_lowering::use_angle_brackets,
+            vec![(self.open_param, String::from("<")), (self.close_param, String::from(">"))],
+            Applicability::MaybeIncorrect,
+        );
+    }
+}

compiler/rustc_ast_lowering/src/lib.rs

@@ -75,6 +75,7 @@ macro_rules! arena_vec {
 
 mod asm;
 mod block;
+mod errors;
 mod expr;
 mod index;
 mod item;

compiler/rustc_ast_lowering/src/path.rs

@@ -1,11 +1,11 @@
 use crate::ImplTraitPosition;
 
+use super::errors::{GenericTypeWithParentheses, UseAngleBrackets};
 use super::ResolverAstLoweringExt;
 use super::{GenericArgsCtor, LifetimeRes, ParenthesizedGenericArgs};
 use super::{ImplTraitContext, LoweringContext, ParamMode};
 
 use rustc_ast::{self as ast, *};
-use rustc_errors::{struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, PartialRes, Res};
 use rustc_hir::GenericArg;
@@ -185,18 +185,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     ) -> hir::PathSegment<'hir> {
         debug!("path_span: {:?}, lower_path_segment(segment: {:?})", path_span, segment,);
         let (mut generic_args, infer_args) = if let Some(ref generic_args) = segment.args {
-            let msg = "parenthesized type parameters may only be used with a `Fn` trait";
             match **generic_args {
                 GenericArgs::AngleBracketed(ref data) => {
                     self.lower_angle_bracketed_parameter_data(data, param_mode, itctx)
                 }
                 GenericArgs::Parenthesized(ref data) => match parenthesized_generic_args {
                     ParenthesizedGenericArgs::Ok => self.lower_parenthesized_parameter_data(data),
                     ParenthesizedGenericArgs::Err => {
-                        let mut err = struct_span_err!(self.tcx.sess, data.span, E0214, "{}", msg);
-                        err.span_label(data.span, "only `Fn` traits may use parentheses");
                         // Suggest replacing parentheses with angle brackets `Trait(params...)` to `Trait<params...>`
-                        if !data.inputs.is_empty() {
+                        let sub = if !data.inputs.is_empty() {
                             // Start of the span to the 1st character of 1st argument
                             let open_param = data.inputs_span.shrink_to_lo().to(data
                                 .inputs
@@ -212,16 +209,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 .span
                                 .shrink_to_hi()
                                 .to(data.inputs_span.shrink_to_hi());
-                            err.multipart_suggestion(
-                                &format!("use angle brackets instead",),
-                                vec![
-                                    (open_param, String::from("<")),
-                                    (close_param, String::from(">")),
-                                ],
-                                Applicability::MaybeIncorrect,
-                            );
-                        }
-                        err.emit();
+
+                            Some(UseAngleBrackets { open_param, close_param })
+                        } else {
+                            None
+                        };
+                        self.tcx.sess.emit_err(GenericTypeWithParentheses { span: data.span, sub });
                         (
                             self.lower_angle_bracketed_parameter_data(
                                 &data.as_angle_bracketed_args(),

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

@@ -0,0 +1,5 @@
+ast_lowering_generic_type_with_parentheses =
+    parenthesized type parameters may only be used with a `Fn` trait
+    .label = only `Fn` traits may use parentheses
+
+ast_lowering_use_angle_brackets = use angle brackets instead

compiler/rustc_error_messages/src/lib.rs

@@ -32,6 +32,7 @@ pub use unic_langid::{langid, LanguageIdentifier};
 
 // Generates `DEFAULT_LOCALE_RESOURCES` static and `fluent_generated` module.
 fluent_messages! {
+    ast_lowering => "../locales/en-US/ast_lowering.ftl",
     ast_passes => "../locales/en-US/ast_passes.ftl",
     borrowck => "../locales/en-US/borrowck.ftl",
     builtin_macros => "../locales/en-US/builtin_macros.ftl",