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Do not call extern_crate on current trait on crate mismatch errors
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When we encounter an error caused by traits/types of different versions of the same crate, filter out the current crate when collecting spans to add to the context so we don't call `extern_crate` on the `DefId` of the current crate, which is meaningless and ICEs.

Produced output with this filter:

```
error[E0277]: the trait bound `foo::Struct: Trait` is not satisfied
  --> y.rs:13:19
   |
13 |     check_trait::<foo::Struct>();
   |                   ^^^^^^^^^^^ the trait `Trait` is not implemented for `foo::Struct`
   |
note: there are multiple different versions of crate `foo` in the dependency graph
  --> y.rs:7:1
   |
4  | extern crate foo;
   | ----------------- one version of crate `foo` is used here, as a direct dependency of the current crate
5  |
6  | pub struct Struct;
   | ----------------- this type implements the required trait
7  | pub trait Trait {}
   | ^^^^^^^^^^^^^^^ this is the required trait
   |
  ::: x.rs:4:1
   |
4  | pub struct Struct;
   | ----------------- this type doesn't implement the required trait
5  | pub trait Trait {}
   | --------------- this is the found trait
   = note: two types coming from two different versions of the same crate are different types even if they look the same
   = help: you can use `cargo tree` to explore your dependency tree
note: required by a bound in `check_trait`
  --> y.rs:10:19
   |
10 | fn check_trait<T: Trait>() {}
   |                   ^^^^^ required by this bound in `check_trait`
```

Fix rust-lang#133563.
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estebank committed Nov 28, 2024
1 parent 9b4d7c6 commit 8574f37
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Original file line number Diff line number Diff line change
Expand Up @@ -1731,6 +1731,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
span.push_span_label(self.tcx.def_span(trait_def_id), "this is the required trait");
for (sp, label) in [trait_def_id, other_trait_def_id]
.iter()
// The current crate-version might depend on another version of the same crate
// (Think "semver-trick"). Do not call `extern_crate` in that case for the local
// crate as that doesn't make sense and ICEs (#133563).
.filter(|def_id| !def_id.is_local())
.filter_map(|def_id| self.tcx.extern_crate(def_id.krate))
.map(|data| {
let dependency = if data.dependency_of == LOCAL_CRATE {
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
#![crate_type = "lib"]
#![crate_name = "foo"]

extern crate foo;

pub struct Struct;
pub trait Trait {}
impl Trait for Struct {}

fn check_trait<T: Trait>() {}

fn ice() {
check_trait::<foo::Struct>();
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
#![crate_type = "lib"]
#![crate_name = "foo"]

pub struct Struct;
pub trait Trait {}
impl Trait for Struct {}
32 changes: 32 additions & 0 deletions tests/run-make/crate-loading-crate-depends-on-itself/rmake.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
//@ only-linux
//@ ignore-wasm32
//@ ignore-wasm64
// ignore-tidy-linelength

// Verify that if the current crate depends on a different version of the same crate, *and* types
// and traits of the different versions are mixed, we produce diagnostic output and not an ICE.
// #133563

use run_make_support::{rust_lib_name, rustc};

fn main() {
rustc().input("foo-prev.rs").run();

rustc()
.extra_filename("current")
.metadata("current")
.input("foo-current.rs")
.extern_("foo", rust_lib_name("foo"))
.run_fail()
.assert_stderr_contains(r#"
note: there are multiple different versions of crate `foo` in the dependency graph
--> foo-current.rs:7:1
|
4 | extern crate foo;
| ----------------- one version of crate `foo` is used here, as a direct dependency of the current crate
5 |
6 | pub struct Struct;
| ----------------- this type implements the required trait
7 | pub trait Trait {}
| ^^^^^^^^^^^^^^^ this is the required trait"#);
}

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