bjoernager/rust
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Add a feature gate for basic function pointer use in const fn

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This commit is contained in:
Dylan MacKenzie 2020-09-24 16:17:03 -07:00
parent 1d216fef3e
commit 1ff143191c
7 changed files with 29 additions and 7 deletions
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28
compiler/rustc_mir/src/transform/check_consts/ops.rs
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@ -213,11 +213,21 @@ impl NonConstOp for FnPtrCast {
const STOPS_CONST_CHECKING: bool = true;
fn status_in_item(&self, ccx: &ConstCx<'_, '_>) -> Status {
mcf_status_in_item(ccx)
if ccx.const_kind() != hir::ConstContext::ConstFn {
Status::Allowed
} else {
Status::Unstable(sym::const_fn_fn_ptr_basics)
}
}
fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) {
mcf_emit_error(ccx, span, "function pointer casts are not allowed in const fn");
feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_fn_fn_ptr_basics,
span,
&format!("function pointer casts are not allowed in {}s", ccx.const_kind()),
)
.emit()
}
}
@ -596,17 +606,21 @@ pub mod ty {
const STOPS_CONST_CHECKING: bool = true;
fn status_in_item(&self, ccx: &ConstCx<'_, '_>) -> Status {
// FIXME: This attribute a hack to allow the specialization of the `futures` API. See
// #59739. We should have a proper feature gate for this.
if ccx.tcx.has_attr(ccx.def_id.to_def_id(), sym::rustc_allow_const_fn_ptr) {
if ccx.const_kind() != hir::ConstContext::ConstFn {
Status::Allowed
} else {
mcf_status_in_item(ccx)
Status::Unstable(sym::const_fn_fn_ptr_basics)
}
}
fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) {
mcf_emit_error(ccx, span, "function pointers in const fn are unstable");
feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_fn_fn_ptr_basics,
span,
&format!("function pointers cannot appear in {}s", ccx.const_kind()),
)
.emit()
}
}