From df5f247a5c5432fc85a84cafb8461fafd01cf6ae Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 22 Nov 2022 01:36:35 +0000
Subject: [PATCH] Delay bug to deduplicate diagnostics

---
 .../src/check/compare_method.rs                | 18 ++++++++++--------
 .../in-trait/trait-more-generics-than-impl.rs  |  1 -
 .../trait-more-generics-than-impl.stderr       | 11 +----------
 3 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/compiler/rustc_hir_analysis/src/check/compare_method.rs b/compiler/rustc_hir_analysis/src/check/compare_method.rs
index 10089453ed6ca..6a17847875877 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_method.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_method.rs
@@ -49,11 +49,11 @@ pub(crate) fn compare_impl_method<'tcx>(
         return;
     }
 
-    if let Err(_) = compare_number_of_generics(tcx, impl_m, trait_m, trait_item_span) {
+    if let Err(_) = compare_number_of_generics(tcx, impl_m, trait_m, trait_item_span, false) {
         return;
     }
 
-    if let Err(_) = compare_generic_param_kinds(tcx, impl_m, trait_m) {
+    if let Err(_) = compare_generic_param_kinds(tcx, impl_m, trait_m, false) {
         return;
     }
 
@@ -349,8 +349,8 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
     let param_env = tcx.param_env(def_id);
 
     // First, check a few of the same thing as `compare_impl_method`, just so we don't ICE during substitutions later.
-    compare_number_of_generics(tcx, impl_m, trait_m, tcx.hir().span_if_local(impl_m.def_id))?;
-    compare_generic_param_kinds(tcx, impl_m, trait_m)?;
+    compare_number_of_generics(tcx, impl_m, trait_m, tcx.hir().span_if_local(impl_m.def_id), true)?;
+    compare_generic_param_kinds(tcx, impl_m, trait_m, true)?;
 
     let trait_to_impl_substs = impl_trait_ref.substs;
 
@@ -927,6 +927,7 @@ fn compare_number_of_generics<'tcx>(
     impl_: &ty::AssocItem,
     trait_: &ty::AssocItem,
     trait_span: Option<Span>,
+    delay: bool,
 ) -> Result<(), ErrorGuaranteed> {
     let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts();
     let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts();
@@ -1056,7 +1057,7 @@ fn compare_number_of_generics<'tcx>(
                 err.span_label(*span, "`impl Trait` introduces an implicit type parameter");
             }
 
-            let reported = err.emit();
+            let reported = err.emit_unless(delay);
             err_occurred = Some(reported);
         }
     }
@@ -1308,6 +1309,7 @@ fn compare_generic_param_kinds<'tcx>(
     tcx: TyCtxt<'tcx>,
     impl_item: &ty::AssocItem,
     trait_item: &ty::AssocItem,
+    delay: bool,
 ) -> Result<(), ErrorGuaranteed> {
     assert_eq!(impl_item.kind, trait_item.kind);
 
@@ -1365,7 +1367,7 @@ fn compare_generic_param_kinds<'tcx>(
             err.span_label(impl_header_span, "");
             err.span_label(param_impl_span, make_param_message("found", param_impl));
 
-            let reported = err.emit();
+            let reported = err.emit_unless(delay);
             return Err(reported);
         }
     }
@@ -1491,9 +1493,9 @@ pub(crate) fn compare_ty_impl<'tcx>(
     debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref);
 
     let _: Result<(), ErrorGuaranteed> = (|| {
-        compare_number_of_generics(tcx, impl_ty, trait_ty, trait_item_span)?;
+        compare_number_of_generics(tcx, impl_ty, trait_ty, trait_item_span, false)?;
 
-        compare_generic_param_kinds(tcx, impl_ty, trait_ty)?;
+        compare_generic_param_kinds(tcx, impl_ty, trait_ty, false)?;
 
         let sp = tcx.def_span(impl_ty.def_id);
         compare_type_predicate_entailment(tcx, impl_ty, sp, trait_ty, impl_trait_ref)?;
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
index 608006203d90b..0bbe50ea6fd37 100644
--- a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.rs
@@ -10,7 +10,6 @@ trait Foo {
 impl Foo for S {
     fn bar() -> impl Sized {}
     //~^ ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
-    //~| ERROR method `bar` has 0 type parameters but its trait declaration has 1 type parameter
 }
 
 fn main() {
diff --git a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
index acde1f7654b76..8ff54cad95139 100644
--- a/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
+++ b/src/test/ui/impl-trait/in-trait/trait-more-generics-than-impl.stderr
@@ -7,15 +7,6 @@ LL |     fn bar<T>() -> impl Sized;
 LL |     fn bar() -> impl Sized {}
    |           ^ found 0 type parameters
 
-error[E0049]: method `bar` has 0 type parameters but its trait declaration has 1 type parameter
-  --> $DIR/trait-more-generics-than-impl.rs:11:11
-   |
-LL |     fn bar<T>() -> impl Sized;
-   |            - expected 1 type parameter
-...
-LL |     fn bar() -> impl Sized {}
-   |           ^ found 0 type parameters
-
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
 For more information about this error, try `rustc --explain E0049`.