Remove rustc_allow_const_fn_ptr

This was a hack to work around the lack of an escape hatch for the "min
`const fn`" checks in const-stable functions. Now that we have co-opted
`allow_internal_unstable` for this purpose, we no longer need the
bespoke attribute.
This commit is contained in:
Dylan MacKenzie 2020-09-24 16:15:41 -07:00
parent 1ff143191c
commit 3cbd17fcc6
6 changed files with 8 additions and 42 deletions

View File

@ -145,8 +145,6 @@ pub struct ConstStability {
pub feature: Symbol,
/// whether the function has a `#[rustc_promotable]` attribute
pub promotable: bool,
/// whether the function has a `#[rustc_allow_const_fn_ptr]` attribute
pub allow_const_fn_ptr: bool,
}
/// The available stability levels.
@ -190,7 +188,6 @@ where
let mut stab: Option<Stability> = None;
let mut const_stab: Option<ConstStability> = None;
let mut promotable = false;
let mut allow_const_fn_ptr = false;
let diagnostic = &sess.parse_sess.span_diagnostic;
'outer: for attr in attrs_iter {
@ -200,7 +197,6 @@ where
sym::unstable,
sym::stable,
sym::rustc_promotable,
sym::rustc_allow_const_fn_ptr,
]
.iter()
.any(|&s| attr.has_name(s))
@ -215,9 +211,6 @@ where
if attr.has_name(sym::rustc_promotable) {
promotable = true;
}
if attr.has_name(sym::rustc_allow_const_fn_ptr) {
allow_const_fn_ptr = true;
}
// attributes with data
else if let Some(MetaItem { kind: MetaItemKind::List(ref metas), .. }) = meta {
let meta = meta.as_ref().unwrap();
@ -360,12 +353,8 @@ where
if sym::unstable == meta_name {
stab = Some(Stability { level, feature });
} else {
const_stab = Some(ConstStability {
level,
feature,
promotable: false,
allow_const_fn_ptr: false,
});
const_stab =
Some(ConstStability { level, feature, promotable: false });
}
}
(None, _, _) => {
@ -440,12 +429,8 @@ where
if sym::stable == meta_name {
stab = Some(Stability { level, feature });
} else {
const_stab = Some(ConstStability {
level,
feature,
promotable: false,
allow_const_fn_ptr: false,
});
const_stab =
Some(ConstStability { level, feature, promotable: false });
}
}
(None, _) => {
@ -464,18 +449,16 @@ where
}
// Merge the const-unstable info into the stability info
if promotable || allow_const_fn_ptr {
if promotable {
if let Some(ref mut stab) = const_stab {
stab.promotable = promotable;
stab.allow_const_fn_ptr = allow_const_fn_ptr;
} else {
struct_span_err!(
diagnostic,
item_sp,
E0717,
"rustc_promotable and rustc_allow_const_fn_ptr attributes \
must be paired with either a rustc_const_unstable or a rustc_const_stable \
attribute"
"`rustc_promotable` attribute must be paired with either a `rustc_const_unstable` \
or a `rustc_const_stable` attribute"
)
.emit();
}

View File

@ -464,7 +464,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
// ==========================================================================
rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
rustc_attr!(rustc_allow_const_fn_ptr, AssumedUsed, template!(Word), IMPL_DETAIL),
rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
// ==========================================================================

View File

@ -457,10 +457,6 @@ rustc_queries! {
desc { |tcx| "checking if item is promotable: `{}`", tcx.def_path_str(key) }
}
query const_fn_is_allowed_fn_ptr(key: DefId) -> bool {
desc { |tcx| "checking if const fn allows `fn()` types: `{}`", tcx.def_path_str(key) }
}
/// Returns `true` if this is a foreign item (i.e., linked via `extern { ... }`).
query is_foreign_item(key: DefId) -> bool {
desc { |tcx| "checking if `{}` is a foreign item", tcx.def_path_str(key) }

View File

@ -151,17 +151,11 @@ fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
}
}
fn const_fn_is_allowed_fn_ptr(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
is_const_fn(tcx, def_id)
&& tcx.lookup_const_stability(def_id).map(|stab| stab.allow_const_fn_ptr).unwrap_or(false)
}
pub fn provide(providers: &mut Providers) {
*providers = Providers {
is_const_fn_raw,
is_const_impl_raw: |tcx, def_id| is_const_impl_raw(tcx, def_id.expect_local()),
is_promotable_const_fn,
const_fn_is_allowed_fn_ptr,
..*providers
};
}

View File

@ -885,7 +885,6 @@ symbols! {
rustc,
rustc_allocator,
rustc_allocator_nounwind,
rustc_allow_const_fn_ptr,
rustc_args_required_const,
rustc_attrs,
rustc_builtin_macro,

View File

@ -129,14 +129,9 @@ impl RawWakerVTable {
/// associated task.
#[rustc_promotable]
#[stable(feature = "futures_api", since = "1.36.0")]
// `rustc_allow_const_fn_ptr` is a hack that should not be used anywhere else
// without first consulting with T-Lang.
//
// FIXME: remove whenever we have a stable way to accept fn pointers from const fn
// (see https://github.com/rust-rfcs/const-eval/issues/19#issuecomment-472799062)
#[rustc_allow_const_fn_ptr]
#[rustc_const_stable(feature = "futures_api", since = "1.36.0")]
#[cfg_attr(not(bootstrap), allow_internal_unstable(const_fn_fn_ptr_basics))]
#[cfg_attr(bootstrap, rustc_allow_const_fn_ptr)]
pub const fn new(
clone: unsafe fn(*const ()) -> RawWaker,
wake: unsafe fn(*const ()),