Support Option and similar enums as type of static variable with linkage attribute.

Compiler MCP:
https://github.com/rust-lang/compiler-team/issues/565
This commit is contained in:
Peter Collingbourne 2022-11-23 18:15:50 -08:00
parent 5873ebeef3
commit f44a0153bc
7 changed files with 67 additions and 5 deletions

View File

@ -494,6 +494,7 @@ E0786: include_str!("./error_codes/E0786.md"),
E0787: include_str!("./error_codes/E0787.md"),
E0788: include_str!("./error_codes/E0788.md"),
E0790: include_str!("./error_codes/E0790.md"),
E0791: include_str!("./error_codes/E0791.md"),
;
// E0006, // merged with E0005
// E0008, // cannot bind by-move into a pattern guard

View File

@ -0,0 +1,41 @@
Static variables with the `#[linkage]` attribute within external blocks
must have one of the following types, which are equivalent to a nullable
pointer in C:
* `*mut T` or `*const T`, where `T` may be any type.
* An enumerator type with no `#[repr]` attribute and with two variants, where
one of the variants has no fields, and the other has a single field of one of
the following non-nullable types:
* Reference type
* Function pointer type
The variants can appear in either order.
For example, the following declaration is invalid:
```compile_fail,E0791
#![feature(linkage)]
extern "C" {
#[linkage = "extern_weak"]
static foo: i8;
}
```
The following declarations are valid:
```
#![feature(linkage)]
extern "C" {
#[linkage = "extern_weak"]
static foo: Option<unsafe extern "C" fn()>;
#[linkage = "extern_weak"]
static bar: Option<&'static i8>;
#[linkage = "extern_weak"]
static baz: *mut i8;
}
```

View File

@ -115,4 +115,4 @@ hir_analysis_self_in_impl_self =
.note = replace `Self` with a different type
hir_analysis_linkage_type =
must have type `*const T` or `*mut T` due to `#[linkage]` attribute
invalid type for variable with `#[linkage]` attribute

View File

@ -21,7 +21,7 @@ use rustc_middle::middle::stability::EvalResult;
use rustc_middle::ty::layout::{LayoutError, MAX_SIMD_LANES};
use rustc_middle::ty::subst::GenericArgKind;
use rustc_middle::ty::util::{Discr, IntTypeExt};
use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable};
use rustc_middle::ty::{self, AdtDef, ParamEnv, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable};
use rustc_session::lint::builtin::{UNINHABITED_STATIC, UNSUPPORTED_CALLING_CONVENTIONS};
use rustc_span::symbol::sym;
use rustc_span::{self, Span};
@ -479,10 +479,29 @@ fn check_opaque_meets_bounds<'tcx>(
let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
}
fn is_enum_of_nonnullable_ptr<'tcx>(
tcx: TyCtxt<'tcx>,
adt_def: AdtDef<'tcx>,
substs: SubstsRef<'tcx>,
) -> bool {
if adt_def.repr().inhibit_enum_layout_opt() {
return false;
}
let [var_one, var_two] = &adt_def.variants().raw[..] else {
return false;
};
let (([], [field]) | ([field], [])) = (&var_one.fields[..], &var_two.fields[..]) else {
return false;
};
matches!(field.ty(tcx, substs).kind(), ty::FnPtr(..) | ty::Ref(..))
}
fn check_static_linkage<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
if tcx.codegen_fn_attrs(def_id).import_linkage.is_some() {
if match tcx.type_of(def_id).kind() {
ty::RawPtr(_) => false,
ty::Adt(adt_def, substs) => !is_enum_of_nonnullable_ptr(tcx, *adt_def, *substs),
_ => true,
} {
tcx.sess.emit_err(LinkageType { span: tcx.def_span(def_id) });

View File

@ -287,7 +287,7 @@ pub struct SelfInImplSelf {
}
#[derive(Diagnostic)]
#[diag(hir_analysis_linkage_type)]
#[diag(hir_analysis_linkage_type, code = "E0791")]
pub(crate) struct LinkageType {
#[primary_span]
pub span: Span,

View File

@ -5,7 +5,7 @@
extern "C" {
#[linkage = "extern_weak"]
static foo: i32;
//~^ ERROR: must have type `*const T` or `*mut T` due to `#[linkage]` attribute
//~^ ERROR: invalid type for variable with `#[linkage]` attribute
}
fn main() {

View File

@ -1,4 +1,4 @@
error: must have type `*const T` or `*mut T` due to `#[linkage]` attribute
error[E0791]: invalid type for variable with `#[linkage]` attribute
--> $DIR/linkage2.rs:7:5
|
LL | static foo: i32;
@ -6,3 +6,4 @@ LL | static foo: i32;
error: aborting due to previous error
For more information about this error, try `rustc --explain E0791`.