Rollup merge of #112508 - compiler-errors:trait-sig-lifetime-sugg-ice, r=cjgillot

Tweak spans for self arg, fix borrow suggestion for signature mismatch

1. Adjust a suggestion message that was annoying me
2. Fix #112503 by recording the right spans for the `self` part of the `&self` 0th argument
3. Remove the suggestion for adjusting a trait signature on type mismatch, bc that's gonna probably break all the other impls of the trait even if it fixes its one usage :sweat_smile:

2 files changed, 42 insertions, 11 deletions

diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index 54e22cc3d7f..dde9e9c9ac6 100644
--- a/compiler/rustc_trait_selection/src/errors.rs
+++ b/compiler/rustc_trait_selection/src/errors.rs
@@ -1,5 +1,8 @@
 use crate::fluent_generated as fluent;
-use rustc_errors::{ErrorGuaranteed, Handler, IntoDiagnostic};
+use rustc_errors::{
+    AddToDiagnostic, Applicability, Diagnostic, ErrorGuaranteed, Handler, IntoDiagnostic,
+    SubdiagnosticMessage,
+};
 use rustc_macros::Diagnostic;
 use rustc_middle::ty::{self, PolyTraitRef, Ty};
 use rustc_span::{Span, Symbol};
@@ -97,3 +100,34 @@ pub struct InherentProjectionNormalizationOverflow {
     pub span: Span,
     pub ty: String,
 }
+
+pub enum AdjustSignatureBorrow {
+    Borrow { to_borrow: Vec<(Span, String)> },
+    RemoveBorrow { remove_borrow: Vec<(Span, String)> },
+}
+
+impl AddToDiagnostic for AdjustSignatureBorrow {
+    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
+    where
+        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
+    {
+        match self {
+            AdjustSignatureBorrow::Borrow { to_borrow } => {
+                diag.set_arg("len", to_borrow.len());
+                diag.multipart_suggestion_verbose(
+                    fluent::trait_selection_adjust_signature_borrow,
+                    to_borrow,
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            AdjustSignatureBorrow::RemoveBorrow { remove_borrow } => {
+                diag.set_arg("len", remove_borrow.len());
+                diag.multipart_suggestion_verbose(
+                    fluent::trait_selection_adjust_signature_remove_borrow,
+                    remove_borrow,
+                    Applicability::MaybeIncorrect,
+                );
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 073a2a2b1a0..05d2934d4c5 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -5,6 +5,7 @@ use super::{
     PredicateObligation,
 };
 
+use crate::errors;
 use crate::infer::InferCtxt;
 use crate::traits::{NormalizeExt, ObligationCtxt};
 
@@ -4031,6 +4032,10 @@ fn hint_missing_borrow<'tcx>(
     found_node: Node<'_>,
     err: &mut Diagnostic,
 ) {
+    if matches!(found_node, Node::TraitItem(..)) {
+        return;
+    }
+
     let found_args = match found.kind() {
         ty::FnPtr(f) => infcx.instantiate_binder_with_placeholders(*f).inputs().iter(),
         kind => {
@@ -4102,19 +4107,11 @@ fn hint_missing_borrow<'tcx>(
     }
 
     if !to_borrow.is_empty() {
-        err.multipart_suggestion_verbose(
-            "consider borrowing the argument",
-            to_borrow,
-            Applicability::MaybeIncorrect,
-        );
+        err.subdiagnostic(errors::AdjustSignatureBorrow::Borrow { to_borrow });
     }
 
     if !remove_borrow.is_empty() {
-        err.multipart_suggestion_verbose(
-            "do not borrow the argument",
-            remove_borrow,
-            Applicability::MaybeIncorrect,
-        );
+        err.subdiagnostic(errors::AdjustSignatureBorrow::RemoveBorrow { remove_borrow });
     }
 }