user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Refactor and document the repeat length check

Browse source
This commit is contained in:
Oli Scherer 2022-04-29 18:56:57 +00:00
parent be54947315
commit 67ce547f47
1 changed files with 22 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

41
compiler/rustc_typeck/src/check/expr.rs
View file

@ -1304,31 +1304,34 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
element_ty: Ty<'tcx>,
) {
let tcx = self.tcx;
let is_const = match &element.kind {
hir::ExprKind::ConstBlock(..) => true,
// Actual constants as the repeat element get inserted repeatedly instead of getting copied via Copy.
match &element.kind {
hir::ExprKind::ConstBlock(..) => return,
hir::ExprKind::Path(qpath) => {
let res = self.typeck_results.borrow().qpath_res(qpath, element.hir_id);
matches!(
res,
Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::AnonConst, _)
)
if let Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::AnonConst, _) = res
{
return;
}
}
_ => {}
}
// If someone calls a const fn, they can extract that call out into a separate constant (or a const
// block in the future), so we check that to tell them that in the diagnostic. Does not affect typeck.
let is_const_fn = match element.kind {
hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() {
ty::FnDef(def_id, _) => tcx.is_const_fn(def_id),
_ => false,
},
_ => false,
};
if !is_const {
let is_const_fn = match element.kind {
hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() {
ty::FnDef(def_id, _) => tcx.is_const_fn(def_id),
_ => false,
},
_ => false,
};
if count.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) {
let lang_item = self.tcx.require_lang_item(LangItem::Copy, None);
let code = traits::ObligationCauseCode::RepeatElementCopy { is_const_fn };
self.require_type_meets(element_ty, element.span, code, lang_item);
}
// If the length is 0, we don't create any elements, so we don't copy any. If the length is 1, we
// don't copy that one element, we move it. Only check for Copy if the length is larger.
if count.try_eval_usize(tcx, self.param_env).map_or(true, |len| len > 1) {
let lang_item = self.tcx.require_lang_item(LangItem::Copy, None);
let code = traits::ObligationCauseCode::RepeatElementCopy { is_const_fn };
self.require_type_meets(element_ty, element.span, code, lang_item);
}
}