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Allow #[target_feature] on safe functions

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This commit is contained in:
LeSeulArtichaut 2020-05-01 14:17:02 +02:00
parent eece58a8e3
commit 2474f0ed88
3 changed files with 47 additions and 8 deletions
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3
src/librustc_feature/active.rs
View file

@ -559,6 +559,9 @@ declare_features! (
/// Allow negative trait implementations.
(active, negative_impls, "1.44.0", Some(68318), None),
/// Allows the use of `#[target_feature]` on safe functions.
(active, target_feature_11, "1.45.0", Some(69098), None),
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------

1
src/librustc_span/symbol.rs
View file

@ -722,6 +722,7 @@ symbols! {
suggestion,
sync_trait,
target_feature,
target_feature_11,
target_has_atomic,
target_has_atomic_load_store,
target_thread_local,

51
src/librustc_typeck/collect.rs
View file

@ -29,7 +29,7 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::weak_lang_items;
use rustc_hir::{GenericParamKind, Node, Unsafety};
use rustc_hir::{GenericParamKind, Node};
use rustc_middle::hir::map::blocks::FnLikeNode;
use rustc_middle::hir::map::Map;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
@ -2413,13 +2413,12 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
codegen_fn_attrs.export_name = Some(s);
}
} else if attr.check_name(sym::target_feature) {
if tcx.is_closure(id) || tcx.fn_sig(id).unsafety() == Unsafety::Normal {
let msg = "`#[target_feature(..)]` can only be applied to `unsafe` functions";
tcx.sess
.struct_span_err(attr.span, msg)
.span_label(attr.span, "can only be applied to `unsafe` functions")
.span_label(tcx.def_span(id), "not an `unsafe` function")
.emit();
if !tcx.features().target_feature_11 {
check_target_feature_safe_fn(tcx, id, attr.span);
} else if let Some(local_id) = id.as_local() {
if tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
check_target_feature_trait_unsafe(tcx, local_id, attr.span);
}
}
from_target_feature(tcx, id, attr, &whitelist, &mut codegen_fn_attrs.target_features);
} else if attr.check_name(sym::linkage) {
@ -2666,3 +2665,39 @@ fn check_link_name_xor_ordinal(
tcx.sess.err(msg);
}
}
/// Checks the function annotated with `#[target_feature]` is unsafe,
/// reporting an error if it isn't.
fn check_target_feature_safe_fn(tcx: TyCtxt<'_>, id: DefId, attr_span: Span) {
if tcx.is_closure(id) || tcx.fn_sig(id).unsafety() == hir::Unsafety::Normal {
let mut err = feature_err(
&tcx.sess.parse_sess,
sym::target_feature_11,
attr_span,
"`#[target_feature(..)]` can only be applied to `unsafe` functions",
);
err.span_label(tcx.def_span(id), "not an `unsafe` function");
err.emit();
}
}
/// Checks the function annotated with `#[target_feature]` is not a safe
/// trait method implementation, reporting an error if it is.
fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
let hir_id = tcx.hir().as_local_hir_id(id);
let node = tcx.hir().get(hir_id);
if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
let parent_id = tcx.hir().get_parent_item(hir_id);
let parent_item = tcx.hir().expect_item(parent_id);
if let hir::ItemKind::Impl { of_trait: Some(_), .. } = parent_item.kind {
tcx.sess
.struct_span_err(
attr_span,
"`#[target_feature(..)]` cannot be applied to safe trait method",
)
.span_label(attr_span, "cannot be applied to safe trait method")
.span_label(tcx.def_span(id), "not an `unsafe` function")
.emit();
}
}
}