From af47257c0dfc5b38468417d36a465a613c675d6e Mon Sep 17 00:00:00 2001
From: David Wood <david.wood@huawei.com>
Date: Fri, 6 May 2022 03:46:12 +0100
Subject: [PATCH] typeck: port "explicit generic args w/ impl trait"

Port the "explicit generic arguments with impl trait" diagnostic to
using the diagnostic derive.

Signed-off-by: David Wood <david.wood@huawei.com>
---
 .../locales/en-US/typeck.ftl                  |  8 ++++++
 compiler/rustc_typeck/src/astconv/generics.rs | 28 ++++---------------
 compiler/rustc_typeck/src/errors.rs           | 13 +++++++++
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/compiler/rustc_error_messages/locales/en-US/typeck.ftl b/compiler/rustc_error_messages/locales/en-US/typeck.ftl
index 80eacd41add3c..aef18fcafaa05 100644
--- a/compiler/rustc_error_messages/locales/en-US/typeck.ftl
+++ b/compiler/rustc_error_messages/locales/en-US/typeck.ftl
@@ -93,3 +93,11 @@ typeck-expected-return-type = expected `{$expected}` because of return type
 
 typeck-unconstrained-opaque-type = unconstrained opaque type
     .note = `{$name}` must be used in combination with a concrete type within the same module
+
+typeck-explicit-generic-args-with-impl-trait =
+    cannot provide explicit generic arguments when `impl Trait` is used in argument position
+    .label = explicit generic argument not allowed
+    .note = see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
+
+typeck-explicit-generic-args-with-impl-trait-feature =
+    add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
diff --git a/compiler/rustc_typeck/src/astconv/generics.rs b/compiler/rustc_typeck/src/astconv/generics.rs
index 794e711b6c831..38c29d3874c9e 100644
--- a/compiler/rustc_typeck/src/astconv/generics.rs
+++ b/compiler/rustc_typeck/src/astconv/generics.rs
@@ -3,7 +3,10 @@ use crate::astconv::{
     AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
     GenericArgCountResult, GenericArgPosition,
 };
-use crate::errors::AssocTypeBindingNotAllowed;
+use crate::errors::{
+    AssocTypeBindingNotAllowed, ExplicitGenericArgsWithImplTrait,
+    ExplicitGenericArgsWithImplTraitFeature,
+};
 use crate::structured_errors::{GenericArgsInfo, StructuredDiagnostic, WrongNumberOfGenericArgs};
 use rustc_ast::ast::ParamKindOrd;
 use rustc_errors::{struct_span_err, Applicability, Diagnostic, MultiSpan};
@@ -636,29 +639,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 })
                 .collect::<Vec<_>>();
 
-            let mut err = struct_span_err! {
-                tcx.sess,
-                spans.clone(),
-                E0632,
-                "cannot provide explicit generic arguments when `impl Trait` is \
-                used in argument position"
-            };
-
-            for span in spans {
-                err.span_label(span, "explicit generic argument not allowed");
-            }
-
-            err.note(
-                "see issue #83701 <https://github.com/rust-lang/rust/issues/83701> \
-                 for more information",
-            );
+            let mut err = tcx.sess.create_err(ExplicitGenericArgsWithImplTrait { spans });
             if tcx.sess.is_nightly_build() {
-                err.help(
-                    "add `#![feature(explicit_generic_args_with_impl_trait)]` \
-                     to the crate attributes to enable",
-                );
+                err.subdiagnostic(ExplicitGenericArgsWithImplTraitFeature);
             }
-
             err.emit();
         }
 
diff --git a/compiler/rustc_typeck/src/errors.rs b/compiler/rustc_typeck/src/errors.rs
index 10c0fcd6bcec5..a3e7108caae00 100644
--- a/compiler/rustc_typeck/src/errors.rs
+++ b/compiler/rustc_typeck/src/errors.rs
@@ -237,3 +237,16 @@ pub struct UnconstrainedOpaqueType {
     pub span: Span,
     pub name: Symbol,
 }
+
+#[derive(SessionDiagnostic)]
+#[error(code = "E0632", slug = "typeck-explicit-generic-args-with-impl-trait")]
+#[note]
+pub struct ExplicitGenericArgsWithImplTrait {
+    #[primary_span]
+    #[label]
+    pub spans: Vec<Span>,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[help(slug = "typeck-explicit-generic-args-with-impl-trait-feature")]
+pub struct ExplicitGenericArgsWithImplTraitFeature;