Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Better error message for generic_const_exprs inference failure #99222

Merged
merged 4 commits into from
Jul 14, 2022
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
27 changes: 27 additions & 0 deletions compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2156,6 +2156,33 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
}
}

ty::PredicateKind::ConstEvaluatable(data) => {
if predicate.references_error() || self.is_tainted_by_errors() {
return;
}
let subst = data.substs.iter().find(|g| g.has_infer_types_or_consts());
if let Some(subst) = subst {
let err = self.emit_inference_failure_err(
body_id,
span,
subst,
ErrorCode::E0284,
true,
);
err
} else {
// If we can't find a substitution, just print a generic error
let mut err = struct_span_err!(
self.tcx.sess,
span,
E0284,
"type annotations needed: cannot satisfy `{}`",
predicate,
);
err.span_label(span, &format!("cannot satisfy `{}`", predicate));
err
}
}
_ => {
if self.tcx.sess.has_errors().is_some() || self.is_tainted_by_errors() {
return;
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@ fn use_dyn<const N: usize>(v: &dyn Foo<N>) where [u8; N + 1]: Sized {
}

fn main() {
// FIXME(generic_const_exprs): Improve the error message here.
use_dyn(&());
//~^ ERROR type annotations needed
}
Original file line number Diff line number Diff line change
@@ -1,14 +1,18 @@
error[E0284]: type annotations needed: cannot satisfy `the constant `use_dyn::<{_: usize}>::{constant#0}` can be evaluated`
--> $DIR/object-safety-ok-infer-err.rs:20:5
error[E0284]: type annotations needed
--> $DIR/object-safety-ok-infer-err.rs:19:5
|
LL | use_dyn(&());
| ^^^^^^^ cannot satisfy `the constant `use_dyn::<{_: usize}>::{constant#0}` can be evaluated`
| ^^^^^^^ cannot infer the value of the const parameter `N` declared on the function `use_dyn`
|
note: required by a bound in `use_dyn`
--> $DIR/object-safety-ok-infer-err.rs:14:55
|
LL | fn use_dyn<const N: usize>(v: &dyn Foo<N>) where [u8; N + 1]: Sized {
| ^^^^^ required by this bound in `use_dyn`
help: consider specifying the generic argument
|
LL | use_dyn::<N>(&());
| +++++

error: aborting due to previous error

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -7,5 +7,5 @@ extern crate generics_of_parent_impl_trait;
fn main() {
// check for `impl Trait<{ const }>` which has a parent of a `DefKind::TyParam`
generics_of_parent_impl_trait::foo([()]);
//~^ error: type annotations needed:
//~^ error: type annotations needed
}
Original file line number Diff line number Diff line change
@@ -1,8 +1,8 @@
error[E0284]: type annotations needed: cannot satisfy `the constant `foo::{opaque#0}::{constant#0}` can be evaluated`
error[E0284]: type annotations needed
--> $DIR/parent_generics_of_encoding_impl_trait.rs:9:5
|
LL | generics_of_parent_impl_trait::foo([()]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot satisfy `the constant `foo::{opaque#0}::{constant#0}` can be evaluated`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer the value of const parameter `N` declared on the function `foo`
|
note: required by a bound in `foo`
--> $DIR/auxiliary/generics_of_parent_impl_trait.rs:6:48
Expand Down