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return unfixed len if pat has reported error
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bvanjoi committed Oct 23, 2023
1 parent 8501f1c commit 6de40ab
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Showing 3 changed files with 47 additions and 1 deletion.
15 changes: 14 additions & 1 deletion compiler/rustc_hir_typeck/src/pat.rs
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ use rustc_hir::pat_util::EnumerateAndAdjustIterator;
use rustc_hir::{HirId, Pat, PatKind};
use rustc_infer::infer;
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::ty::{self, Adt, BindingMode, Ty, TypeVisitableExt};
use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
use rustc_span::edit_distance::find_best_match_for_name;
Expand Down Expand Up @@ -2164,7 +2165,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
len: ty::Const<'tcx>,
min_len: u64,
) -> (Option<Ty<'tcx>>, Ty<'tcx>) {
let guar = if let Some(len) = len.try_eval_target_usize(self.tcx, self.param_env) {
let len = match len.eval(self.tcx, self.param_env, None) {
Ok(val) => val
.try_to_scalar()
.and_then(|scalar| scalar.try_to_int().ok())
.and_then(|int| int.try_to_target_usize(self.tcx).ok()),
Err(ErrorHandled::Reported(..)) => {
let guar = self.error_scrutinee_unfixed_length(span);
return (Some(Ty::new_error(self.tcx, guar)), arr_ty);
}
Err(ErrorHandled::TooGeneric(..)) => None,
};

let guar = if let Some(len) = len {
// Now we know the length...
if slice.is_none() {
// ...and since there is no variable-length pattern,
Expand Down
12 changes: 12 additions & 0 deletions tests/ui/consts/issue-116186.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
#![allow(incomplete_features)]
#![feature(generic_const_exprs)]

fn something(path: [usize; N]) -> impl Clone {
//~^ ERROR cannot find value `N` in this scope
match path {
[] => 0, //~ ERROR cannot pattern-match on an array without a fixed length
_ => 1,
};
}

fn main() {}
21 changes: 21 additions & 0 deletions tests/ui/consts/issue-116186.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
error[E0425]: cannot find value `N` in this scope
--> $DIR/issue-116186.rs:4:28
|
LL | fn something(path: [usize; N]) -> impl Clone {
| ^ not found in this scope
|
help: you might be missing a const parameter
|
LL | fn something<const N: /* Type */>(path: [usize; N]) -> impl Clone {
| +++++++++++++++++++++

error[E0730]: cannot pattern-match on an array without a fixed length
--> $DIR/issue-116186.rs:7:9
|
LL | [] => 0,
| ^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0425, E0730.
For more information about an error, try `rustc --explain E0425`.

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