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delay_span_bug if const-checking an async function

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This errors during AST lowering. Any errors we emit here are just noise.
This commit is contained in:
Dylan MacKenzie 2020-09-29 19:13:25 -07:00
parent 25c7753eee
commit c38aca0502
5 changed files with 38 additions and 61 deletions
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19
compiler/rustc_mir/src/transform/check_consts/validation.rs
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@ -1,8 +1,8 @@
//! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations.
use rustc_errors::struct_span_err;
use rustc_hir::{self as hir, LangItem};
use rustc_hir::{def_id::DefId, HirId};
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::{self as hir, HirId, LangItem};
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::*;
@ -204,6 +204,13 @@ impl Validator<'mir, 'tcx> {
pub fn check_body(&mut self) {
let ConstCx { tcx, body, def_id, .. } = *self.ccx;
// `async` functions cannot be `const fn`. This is checked during AST lowering, so there's
// no need to emit duplicate errors here.
if is_async_fn(tcx, def_id) || body.generator_kind.is_some() {
tcx.sess.delay_span_bug(body.span, "`async` functions cannot be `const fn`");
return;
}
// The local type and predicate checks are not free and only relevant for `const fn`s.
if self.const_kind() == hir::ConstContext::ConstFn {
// Prevent const trait methods from being annotated as `stable`.
@ -877,3 +884,11 @@ fn place_as_reborrow(
fn is_int_bool_or_char(ty: Ty<'_>) -> bool {
ty.is_bool() || ty.is_integral() || ty.is_char()
}
fn is_async_fn(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
let hir_map = tcx.hir();
let hir_id = hir_map.local_def_id_to_hir_id(def_id);
hir_map
.fn_sig_by_hir_id(hir_id)
.map_or(false, |sig| sig.header.asyncness == hir::IsAsync::Async)
}