From af530c4927d4b6018662c092ebcf629f17eb7191 Mon Sep 17 00:00:00 2001
From: Arthur Carcano <arthur.carcano@ocamlpro.com>
Date: Fri, 13 Dec 2024 12:32:35 +0100
Subject: [PATCH] Use a more precise span in placeholder_type_error_diag
Closes: https://github.com/rust-lang/rust/issues/123861
---
compiler/rustc_hir_analysis/src/collect.rs | 7 +--
tests/crashes/123861.rs | 5 --
.../overlapping-errors-span-issue-123861.rs | 8 +++
...verlapping-errors-span-issue-123861.stderr | 52 +++++++++++++++++++
4 files changed, 64 insertions(+), 8 deletions(-)
delete mode 100644 tests/crashes/123861.rs
create mode 100644 tests/ui/generics/overlapping-errors-span-issue-123861.rs
create mode 100644 tests/ui/generics/overlapping-errors-span-issue-123861.stderr
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 96d2714252af9..0bbf6aa5116e0 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -201,12 +201,13 @@ pub(crate) fn placeholder_type_error_diag<'cx, 'tcx>(
placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
if let Some(generics) = generics {
- if let Some(arg) = params.iter().find(|arg| {
- matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
+ if let Some(span) = params.iter().find_map(|arg| match arg.name {
+ hir::ParamName::Plain(Ident { name: kw::Underscore, span }) => Some(span),
+ _ => None,
}) {
// Account for `_` already present in cases like `struct S<_>(_);` and suggest
// `struct S<T>(T);` instead of `struct S<_, T>(T);`.
- sugg.push((arg.span, (*type_name).to_string()));
+ sugg.push((span, (*type_name).to_string()));
} else if let Some(span) = generics.span_for_param_suggestion() {
// Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
sugg.push((span, format!(", {type_name}")));
diff --git a/tests/crashes/123861.rs b/tests/crashes/123861.rs
deleted file mode 100644
index 60245960af0d6..0000000000000
--- a/tests/crashes/123861.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-//@ known-bug: #123861
-//@ needs-rustc-debug-assertions
-
-struct _;
-fn mainIterator<_ = _> {}
diff --git a/tests/ui/generics/overlapping-errors-span-issue-123861.rs b/tests/ui/generics/overlapping-errors-span-issue-123861.rs
new file mode 100644
index 0000000000000..e0a27f6874874
--- /dev/null
+++ b/tests/ui/generics/overlapping-errors-span-issue-123861.rs
@@ -0,0 +1,8 @@
+fn mainIterator<_ = _> {}
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR missing parameters for function definition
+//~| ERROR defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions [invalid_type_param_default]
+//~| WARNING this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+//~| ERROR the placeholder `_` is not allowed within types on item signatures for functions [E0121]
+
+fn main() {}
diff --git a/tests/ui/generics/overlapping-errors-span-issue-123861.stderr b/tests/ui/generics/overlapping-errors-span-issue-123861.stderr
new file mode 100644
index 0000000000000..e0a49343b0e0d
--- /dev/null
+++ b/tests/ui/generics/overlapping-errors-span-issue-123861.stderr
@@ -0,0 +1,52 @@
+error: expected identifier, found reserved identifier `_`
+ --> $DIR/overlapping-errors-span-issue-123861.rs:1:17
+ |
+LL | fn mainIterator<_ = _> {}
+ | ^ expected identifier, found reserved identifier
+
+error: missing parameters for function definition
+ --> $DIR/overlapping-errors-span-issue-123861.rs:1:23
+ |
+LL | fn mainIterator<_ = _> {}
+ | ^
+ |
+help: add a parameter list
+ |
+LL | fn mainIterator<_ = _>() {}
+ | ++
+
+error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+ --> $DIR/overlapping-errors-span-issue-123861.rs:1:17
+ |
+LL | fn mainIterator<_ = _> {}
+ | ^^^^^
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
+ = note: `#[deny(invalid_type_param_default)]` on by default
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
+ --> $DIR/overlapping-errors-span-issue-123861.rs:1:21
+ |
+LL | fn mainIterator<_ = _> {}
+ | ^ not allowed in type signatures
+ |
+help: use type parameters instead
+ |
+LL | fn mainIterator<T = T> {}
+ | ~ ~
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0121`.
+Future incompatibility report: Future breakage diagnostic:
+error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+ --> $DIR/overlapping-errors-span-issue-123861.rs:1:17
+ |
+LL | fn mainIterator<_ = _> {}
+ | ^^^^^
+ |
+ = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+ = note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
+ = note: `#[deny(invalid_type_param_default)]` on by default
+