From 7a378dd0fb2b383be75722666d8a3c761882af15 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bruno=20A=2E=20Muci=C3=B1o?= <mucinoab@gmail.com>
Date: Sun, 27 Nov 2022 20:50:13 -0600
Subject: [PATCH] Avoid ICE if the Clone trait is not found while building
error suggestions
---
.../src/diagnostics/conflict_errors.rs | 16 +++++++-------
.../missing-clone-for-suggestion.rs | 20 ++++++++++++++++++
.../missing-clone-for-suggestion.stderr | 21 +++++++++++++++++++
3 files changed, 50 insertions(+), 7 deletions(-)
create mode 100644 src/test/ui/lang-items/missing-clone-for-suggestion.rs
create mode 100644 src/test/ui/lang-items/missing-clone-for-suggestion.stderr
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index 5ec9c5f5c1b..d221da5c17e 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -732,13 +732,15 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
let tcx = self.infcx.tcx;
// Try to find predicates on *generic params* that would allow copying `ty`
let infcx = tcx.infer_ctxt().build();
- if infcx
- .type_implements_trait(
- tcx.lang_items().clone_trait().unwrap(),
- [tcx.erase_regions(ty)],
- self.param_env,
- )
- .must_apply_modulo_regions()
+
+ if let Some(clone_trait_def) = tcx.lang_items().clone_trait()
+ && infcx
+ .type_implements_trait(
+ clone_trait_def,
+ [tcx.erase_regions(ty)],
+ self.param_env,
+ )
+ .must_apply_modulo_regions()
{
err.span_suggestion_verbose(
span.shrink_to_hi(),
diff --git a/src/test/ui/lang-items/missing-clone-for-suggestion.rs b/src/test/ui/lang-items/missing-clone-for-suggestion.rs
new file mode 100644
index 00000000000..e8290c0098a
--- /dev/null
+++ b/src/test/ui/lang-items/missing-clone-for-suggestion.rs
@@ -0,0 +1,20 @@
+// Avoid panicking if the Clone trait is not found while building error suggestions
+// See #104870
+
+#![feature(no_core, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[lang = "copy"]
+trait Copy {}
+
+fn g<T>(x: T) {}
+
+fn f(x: *mut u8) {
+ g(x);
+ g(x); //~ ERROR use of moved value: `x`
+}
+
+fn main() {}
diff --git a/src/test/ui/lang-items/missing-clone-for-suggestion.stderr b/src/test/ui/lang-items/missing-clone-for-suggestion.stderr
new file mode 100644
index 00000000000..35783a1be78
--- /dev/null
+++ b/src/test/ui/lang-items/missing-clone-for-suggestion.stderr
@@ -0,0 +1,21 @@
+error[E0382]: use of moved value: `x`
+ --> $DIR/missing-clone-for-suggestion.rs:17:7
+ |
+LL | fn f(x: *mut u8) {
+ | - move occurs because `x` has type `*mut u8`, which does not implement the `Copy` trait
+LL | g(x);
+ | - value moved here
+LL | g(x);
+ | ^ value used here after move
+ |
+note: consider changing this parameter type in function `g` to borrow instead if owning the value isn't necessary
+ --> $DIR/missing-clone-for-suggestion.rs:13:12
+ |
+LL | fn g<T>(x: T) {}
+ | - ^ this parameter takes ownership of the value
+ | |
+ | in this function
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0382`.