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Array repeat expression lengths must be monomorphic at MIR building time

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This commit is contained in:
Oliver Scherer 2020-01-16 16:18:08 +01:00
parent 9fe05e9456
commit eed0d33a65
2 changed files with 40 additions and 12 deletions
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27
src/librustc_mir_build/hair/cx/expr.rs
View File

@ -411,18 +411,21 @@ fn make_mirror_unadjusted<'a, 'tcx>(
let def_id = cx.tcx.hir().local_def_id(count.hir_id);
let substs = InternalSubsts::identity_for_item(cx.tcx, def_id);
let span = cx.tcx.def_span(def_id);
let count =
match cx.tcx.const_eval_resolve(cx.param_env, def_id, substs, None, Some(span)) {
Ok(cv) => cv.eval_usize(cx.tcx, cx.param_env),
Err(ErrorHandled::Reported) => 0,
Err(ErrorHandled::TooGeneric) => {
let span = cx.tcx.def_span(def_id);
cx.tcx
.sess
.span_err(span, "array lengths can't depend on generic parameters");
0
}
};
let count = match cx.tcx.const_eval_resolve(
ty::ParamEnv::reveal_all(),
def_id,
substs,
None,
Some(span),
) {
Ok(cv) => cv.eval_usize(cx.tcx, ty::ParamEnv::reveal_all()),
Err(ErrorHandled::Reported) => 0,
Err(ErrorHandled::TooGeneric) => {
let span = cx.tcx.def_span(def_id);
cx.tcx.sess.span_err(span, "array lengths can't depend on generic parameters");
0
}
};
ExprKind::Repeat { value: v.to_ref(), count }
}

25
src/test/ui/consts/associated_const_generic.rs Normal file
View File

@ -0,0 +1,25 @@
// check-pass
trait TraitA {
const VALUE: usize;
}
struct A;
impl TraitA for A {
const VALUE: usize = 1;
}
trait TraitB {
type MyA: TraitA;
const VALUE: usize = Self::MyA::VALUE;
}
struct B;
impl TraitB for B {
type MyA = A;
}
fn main() {
let _ = [0; A::VALUE];
let _ = [0; B::VALUE]; // Indirectly refers to `A::VALUE`
}