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Auto merge of #86492 - hyd-dev:no-mangle-method, r=petrochenkov

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Associated functions that contain extern indicator or have `#[rustc_std_internal_symbol]` are reachable

Previously these fails to link with ``undefined reference to `foo'``:

<details>
<summary>Example 1</summary>

```rs
struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=f1244afcdd26e2a28445f6e82ca46b50))
</details>

<details>
<summary>Example 2</summary>

```rs
#![crate_name = "lib"]
#![crate_type = "lib"]

struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}
```
```rs
extern crate lib;

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
</details>

But I believe they should link successfully, because this works:
<details>

```rs
#[no_mangle]
fn foo() {}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}
```
([Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=789b3f283ee6126f53939429103ed98d))
</details>

This PR fixes the problem, by adding associated functions that have "custom linkage" to `reachable_set`, just like normal functions.

I haven't tested whether #76211 and [Miri](https://github.com/rust-lang/miri/issues/1837) are fixed by this PR yet, but I'm submitting this anyway since this fixes the examples above.

I added a `run-pass` test that combines my two examples above, but I'm not sure if that's the right way to test this. Maybe I should add / modify an existing codegen test (`src/test/codegen/export-no-mangle.rs`?) instead?
This commit is contained in:
bors 2021-08-13 19:47:03 +00:00
commit 5a19ffe1c2
19 changed files with 934 additions and 265 deletions
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86
compiler/rustc_lint/src/builtin.rs
View file

@ -417,6 +417,25 @@ impl EarlyLintPass for UnsafeCode {
}
}
fn check_impl_item(&mut self, cx: &EarlyContext<'_>, it: &ast::AssocItem) {
if let ast::AssocItemKind::Fn(..) = it.kind {
if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::no_mangle) {
self.report_overriden_symbol_name(
cx,
attr.span,
"declaration of a `no_mangle` method",
);
}
if let Some(attr) = cx.sess().find_by_name(&it.attrs, sym::export_name) {
self.report_overriden_symbol_name(
cx,
attr.span,
"declaration of a method with `export_name`",
);
}
}
}
fn check_fn(&mut self, cx: &EarlyContext<'_>, fk: FnKind<'_>, span: Span, _: ast::NodeId) {
if let FnKind::Fn(
ctxt,
@ -1115,31 +1134,37 @@ declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GEN
impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
let attrs = cx.tcx.hir().attrs(it.hir_id());
let check_no_mangle_on_generic_fn = |no_mangle_attr: &ast::Attribute,
impl_generics: Option<&hir::Generics<'_>>,
generics: &hir::Generics<'_>,
span| {
for param in
generics.params.iter().chain(impl_generics.map(|g| g.params).into_iter().flatten())
{
match param.kind {
GenericParamKind::Lifetime { .. } => {}
GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS, span, |lint| {
lint.build("functions generic over types or consts must be mangled")
.span_suggestion_short(
no_mangle_attr.span,
"remove this attribute",
String::new(),
// Use of `#[no_mangle]` suggests FFI intent; correct
// fix may be to monomorphize source by hand
Applicability::MaybeIncorrect,
)
.emit();
});
break;
}
}
}
};
match it.kind {
hir::ItemKind::Fn(.., ref generics, _) => {
if let Some(no_mangle_attr) = cx.sess().find_by_name(attrs, sym::no_mangle) {
for param in generics.params {
match param.kind {
GenericParamKind::Lifetime { .. } => {}
GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {
cx.struct_span_lint(NO_MANGLE_GENERIC_ITEMS, it.span, |lint| {
lint.build(
"functions generic over types or consts must be mangled",
)
.span_suggestion_short(
no_mangle_attr.span,
"remove this attribute",
String::new(),
// Use of `#[no_mangle]` suggests FFI intent; correct
// fix may be to monomorphize source by hand
Applicability::MaybeIncorrect,
)
.emit();
});
break;
}
}
}
check_no_mangle_on_generic_fn(no_mangle_attr, None, generics, it.span);
}
}
hir::ItemKind::Const(..) => {
@ -1170,6 +1195,23 @@ impl<'tcx> LateLintPass<'tcx> for InvalidNoMangleItems {
});
}
}
hir::ItemKind::Impl(hir::Impl { ref generics, items, .. }) => {
for it in items {
if let hir::AssocItemKind::Fn { .. } = it.kind {
if let Some(no_mangle_attr) = cx
.sess()
.find_by_name(cx.tcx.hir().attrs(it.id.hir_id()), sym::no_mangle)
{
check_no_mangle_on_generic_fn(
no_mangle_attr,
Some(generics),
cx.tcx.hir().get_generics(it.id.def_id.to_def_id()).unwrap(),
it.span,
);
}
}
}
}
_ => {}
}
}

8
compiler/rustc_lint/src/nonstandard_style.rs
View file

@ -391,9 +391,14 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
_: Span,
id: hir::HirId,
) {
let attrs = cx.tcx.hir().attrs(id);
match &fk {
FnKind::Method(ident, ..) => match method_context(cx, id) {
FnKind::Method(ident, sig, ..) => match method_context(cx, id) {
MethodLateContext::PlainImpl => {
if sig.header.abi != Abi::Rust && cx.sess().contains_name(attrs, sym::no_mangle)
{
return;
}
self.check_snake_case(cx, "method", ident);
}
MethodLateContext::TraitAutoImpl => {
@ -402,7 +407,6 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
_ => (),
},
FnKind::ItemFn(ident, _, header, _) => {
let attrs = cx.tcx.hir().attrs(id);
// Skip foreign-ABI #[no_mangle] functions (Issue #31924)
if header.abi != Abi::Rust && cx.sess().contains_name(attrs, sym::no_mangle) {
return;