Avoid duplicate requirement diag args in RegionOriginNote

compiler/rustc_trait_selection/src/errors.rs

@@ -477,7 +477,7 @@ pub enum RegionOriginNote<'a> {
 
 impl Subdiagnostic for RegionOriginNote<'_> {
     fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
-        let mut label_or_note = |span, msg: DiagMessage| {
+        let label_or_note = |diag: &mut Diag<'_, G>, span, msg: DiagMessage| {
             let sub_count = diag.children.iter().filter(|d| d.span.is_dummy()).count();
             let expanded_sub_count = diag.children.iter().filter(|d| !d.span.is_dummy()).count();
             let span_is_primary = diag.span.primary_spans().iter().all(|&sp| sp == span);
@@ -491,22 +491,26 @@ impl Subdiagnostic for RegionOriginNote<'_> {
         };
         match self {
             RegionOriginNote::Plain { span, msg } => {
-                label_or_note(span, msg);
+                label_or_note(diag, span, msg);
             }
             RegionOriginNote::WithName { span, msg, name, continues } => {
-                label_or_note(span, msg);
                 diag.arg("name", name);
                 diag.arg("continues", continues);
+                label_or_note(diag, span, msg);
             }
             RegionOriginNote::WithRequirement {
                 span,
                 requirement,
                 expected_found: Some((expected, found)),
             } => {
-                label_or_note(
-                    span,
-                    msg!(
-                        "...so that the {$requirement ->
+                // `RegionOriginNote` can appear multiple times on one diagnostic with different
+                // `requirement` values. Scope args per-note and eagerly translate to avoid
+                // cross-note arg collisions.
+                // See https://github.com/rust-lang/rust/issues/143872 for details.
+                diag.store_args();
+                diag.arg("requirement", requirement);
+                let msg = diag.eagerly_translate(msg!(
+                    "...so that the {$requirement ->
                             [method_compat] method type is compatible with trait
                             [type_compat] associated type is compatible with trait
                             [const_compat] const is compatible with trait
@@ -519,20 +523,20 @@ impl Subdiagnostic for RegionOriginNote<'_> {
                             [method_correct_type] method receiver has the correct type
                             *[other] types are compatible
                         }"
-                    ),
-                );
-                diag.arg("requirement", requirement);
+                ));
+                diag.restore_args();
+                label_or_note(diag, span, msg);
 
                 diag.note_expected_found("", expected, "", found);
             }
             RegionOriginNote::WithRequirement { span, requirement, expected_found: None } => {
                 // FIXME: this really should be handled at some earlier stage. Our
                 // handling of region checking when type errors are present is
                 // *terrible*.
-                label_or_note(
-                    span,
-                    msg!(
-                        "...so that {$requirement ->
+                diag.store_args();
+                diag.arg("requirement", requirement);
+                let msg = diag.eagerly_translate(msg!(
+                    "...so that {$requirement ->
                             [method_compat] method type is compatible with trait
                             [type_compat] associated type is compatible with trait
                             [const_compat] const is compatible with trait
@@ -545,9 +549,9 @@ impl Subdiagnostic for RegionOriginNote<'_> {
                             [method_correct_type] method receiver has the correct type
                             *[other] types are compatible
                         }"
-                    ),
-                );
-                diag.arg("requirement", requirement);
+                ));
+                diag.restore_args();
+                label_or_note(diag, span, msg);
             }
         };
     }

tests/ui/traits/compare-impl-item-conflicting-lifetime-requirements.rs

@@ -0,0 +1,23 @@
+//@ compile-flags: --crate-type=lib
+// Regression test for https://github.com/rust-lang/rust/issues/143872
+
+trait Project {
+    type Ty;
+}
+
+impl Project for &'_ &'static () {
+    type Ty = ();
+}
+
+trait Trait {
+    fn get<'s>(s: &'s str, _: ()) -> &'_ str;
+}
+
+impl Trait for () {
+    fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+        //~^ ERROR cannot infer an appropriate lifetime for lifetime parameter 's in generic type due to conflicting requirements
+        //~| ERROR mismatched types
+        //~| ERROR lifetime may not live long enough
+        s
+    }
+}

tests/ui/traits/compare-impl-item-conflicting-lifetime-requirements.stderr

@@ -0,0 +1,55 @@
+error[E0803]: cannot infer an appropriate lifetime for lifetime parameter 's in generic type due to conflicting requirements
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:5
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: first, the lifetime cannot outlive the lifetime `'s` as defined here...
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:13:12
+   |
+LL |     fn get<'s>(s: &'s str, _: ()) -> &'_ str;
+   |            ^^
+note: ...so that the method type is compatible with trait
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:5
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: expected `fn(&'s _, ()) -> &'s _`
+              found `fn(&_, ()) -> &'static _`
+   = note: but, the lifetime must be valid for the static lifetime...
+note: ...so that the types are compatible
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:5
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: expected `<&&() as Project>`
+              found `<&&'static () as Project>`
+
+error[E0308]: mismatched types
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:31
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |                               ^^^^^^^^^^^^^^^^^^^^^^^^ lifetime mismatch
+   |
+   = note: expected trait `<&&'s () as Project>`
+              found trait `<&&'static () as Project>`
+note: the lifetime `'s` as defined here...
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:12
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |            ^^
+   = note: ...does not necessarily outlive the static lifetime
+
+error: lifetime may not live long enough
+  --> $DIR/compare-impl-item-conflicting-lifetime-requirements.rs:17:5
+   |
+LL |     fn get<'s>(s: &'s str, _: <&&'s () as Project>::Ty) -> &'static str {
+   |     ^^^^^^^--^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     |      |
+   |     |      lifetime `'s` defined here
+   |     requires that `'s` must outlive `'static`
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0308, E0803.
+For more information about an error, try `rustc --explain E0308`.