bjoernager/rust
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Rollup merge of #88963 - fee1-dead:const-iterator, r=oli-obk

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Coerce const FnDefs to implement const Fn traits

You can now pass a FnDef to a function expecting `F` where `F: ~const FnTrait`.

r? ``@oli-obk``

``@rustbot`` label T-compiler F-const_trait_impl
This commit is contained in:
Manish Goregaokar 2021-10-01 14:46:48 -07:00 • committed by GitHub
commit 743e842afb
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 79 additions and 37 deletions
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19
compiler/rustc_const_eval/src/const_eval/fn_queries.rs
View file

@ -6,23 +6,6 @@ use rustc_middle::ty::TyCtxt;
use rustc_span::symbol::Symbol;
use rustc_target::spec::abi::Abi;
/// Whether the `def_id` counts as const fn in your current crate, considering all active
/// feature gates
pub fn is_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
tcx.is_const_fn_raw(def_id)
&& match is_unstable_const_fn(tcx, def_id) {
Some(feature_name) => {
// has a `rustc_const_unstable` attribute, check whether the user enabled the
// corresponding feature gate.
tcx.features().declared_lib_features.iter().any(|&(sym, _)| sym == feature_name)
}
// functions without const stability are either stable user written
// const fn or the user is using feature gates and we thus don't
// care what they do
None => true,
}
}
/// Whether the `def_id` is an unstable const fn and what feature gate is necessary to enable it
pub fn is_unstable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Symbol> {
if tcx.is_const_fn_raw(def_id) {
@ -77,7 +60,7 @@ fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
}
fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
is_const_fn(tcx, def_id)
tcx.is_const_fn(def_id)
&& match tcx.lookup_const_stability(def_id) {
Some(stab) => {
if cfg!(debug_assertions) && stab.promotable {

7
compiler/rustc_const_eval/src/transform/promote_consts.rs
View file

@ -26,7 +26,6 @@ use rustc_index::vec::{Idx, IndexVec};
use std::cell::Cell;
use std::{cmp, iter, mem};
use crate::const_eval::{is_const_fn, is_unstable_const_fn};
use crate::transform::check_consts::{is_lang_panic_fn, qualifs, ConstCx};
use crate::transform::MirPass;
@ -658,9 +657,7 @@ impl<'tcx> Validator<'_, 'tcx> {
let is_const_fn = match *fn_ty.kind() {
ty::FnDef(def_id, _) => {
is_const_fn(self.tcx, def_id)
|| is_unstable_const_fn(self.tcx, def_id).is_some()
|| is_lang_panic_fn(self.tcx, def_id)
self.tcx.is_const_fn_raw(def_id) || is_lang_panic_fn(self.tcx, def_id)
}
_ => false,
};
@ -1081,7 +1078,7 @@ pub fn is_const_fn_in_array_repeat_expression<'tcx>(
if let ty::FnDef(def_id, _) = *literal.ty().kind() {
if let Some((destination_place, _)) = destination {
if destination_place == place {
if is_const_fn(ccx.tcx, def_id) {
if ccx.tcx.is_const_fn(def_id) {
return true;
}
}