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Merged
merged 2 commits into from
Oct 3, 2021
Merged

Make *const (), *mut () okay for FFI #84267

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c17e3e2
Add improper ctypes test for ptr to unit, ptr to tuple
dtolnay Apr 17, 2021
abfad74
Make *const (), *mut () okay for FFI
dtolnay Apr 16, 2021
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9 changes: 9 additions & 0 deletions compiler/rustc_lint/src/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1060,6 +1060,15 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
FfiSafe
}

ty::RawPtr(ty::TypeAndMut { ty, .. })
if match ty.kind() {
ty::Tuple(tuple) => tuple.is_empty(),
_ => false,
} =>
{
FfiSafe
}

ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
self.check_type_for_ffi(cache, ty)
}
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4 changes: 4 additions & 0 deletions src/test/ui/lint/lint-ctypes-fn.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,10 @@ pub extern "C" fn ptr_type1(size: *const Foo) { }

pub extern "C" fn ptr_type2(size: *const Foo) { }

pub extern "C" fn ptr_unit(p: *const ()) { }

pub extern "C" fn ptr_tuple(p: *const ((),)) { }

pub extern "C" fn slice_type(p: &[u32]) { }
//~^ ERROR: uses type `[u32]`

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40 changes: 20 additions & 20 deletions src/test/ui/lint/lint-ctypes-fn.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: `extern` fn uses type `[u32]`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:69:33
--> $DIR/lint-ctypes-fn.rs:73:33
|
LL | pub extern "C" fn slice_type(p: &[u32]) { }
| ^^^^^^ not FFI-safe
Expand All @@ -13,7 +13,7 @@ LL | #![deny(improper_ctypes_definitions)]
= note: slices have no C equivalent

error: `extern` fn uses type `str`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:72:31
--> $DIR/lint-ctypes-fn.rs:76:31
|
LL | pub extern "C" fn str_type(p: &str) { }
| ^^^^ not FFI-safe
Expand All @@ -22,31 +22,31 @@ LL | pub extern "C" fn str_type(p: &str) { }
= note: string slices have no C equivalent

error: `extern` fn uses type `Box<[u8]>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:79:34
--> $DIR/lint-ctypes-fn.rs:83:34
|
LL | pub extern "C" fn boxed_slice(p: Box<[u8]>) { }
| ^^^^^^^^^ not FFI-safe
|
= note: box cannot be represented as a single pointer

error: `extern` fn uses type `Box<str>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:82:35
--> $DIR/lint-ctypes-fn.rs:86:35
|
LL | pub extern "C" fn boxed_string(p: Box<str>) { }
| ^^^^^^^^ not FFI-safe
|
= note: box cannot be represented as a single pointer

error: `extern` fn uses type `Box<dyn Trait>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:85:34
--> $DIR/lint-ctypes-fn.rs:89:34
|
LL | pub extern "C" fn boxed_trait(p: Box<dyn Trait>) { }
| ^^^^^^^^^^^^^^ not FFI-safe
|
= note: box cannot be represented as a single pointer

error: `extern` fn uses type `char`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:88:32
--> $DIR/lint-ctypes-fn.rs:92:32
|
LL | pub extern "C" fn char_type(p: char) { }
| ^^^^ not FFI-safe
Expand All @@ -55,23 +55,23 @@ LL | pub extern "C" fn char_type(p: char) { }
= note: the `char` type has no C equivalent

error: `extern` fn uses type `i128`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:91:32
--> $DIR/lint-ctypes-fn.rs:95:32
|
LL | pub extern "C" fn i128_type(p: i128) { }
| ^^^^ not FFI-safe
|
= note: 128-bit integers don't currently have a known stable ABI

error: `extern` fn uses type `u128`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:94:32
--> $DIR/lint-ctypes-fn.rs:98:32
|
LL | pub extern "C" fn u128_type(p: u128) { }
| ^^^^ not FFI-safe
|
= note: 128-bit integers don't currently have a known stable ABI

error: `extern` fn uses type `(i32, i32)`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:97:33
--> $DIR/lint-ctypes-fn.rs:101:33
|
LL | pub extern "C" fn tuple_type(p: (i32, i32)) { }
| ^^^^^^^^^^ not FFI-safe
Expand All @@ -80,7 +80,7 @@ LL | pub extern "C" fn tuple_type(p: (i32, i32)) { }
= note: tuples have unspecified layout

error: `extern` fn uses type `(i32, i32)`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:100:34
--> $DIR/lint-ctypes-fn.rs:104:34
|
LL | pub extern "C" fn tuple_type2(p: I32Pair) { }
| ^^^^^^^ not FFI-safe
Expand All @@ -89,7 +89,7 @@ LL | pub extern "C" fn tuple_type2(p: I32Pair) { }
= note: tuples have unspecified layout

error: `extern` fn uses type `ZeroSize`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:103:32
--> $DIR/lint-ctypes-fn.rs:107:32
|
LL | pub extern "C" fn zero_size(p: ZeroSize) { }
| ^^^^^^^^ not FFI-safe
Expand All @@ -103,7 +103,7 @@ LL | pub struct ZeroSize;
| ^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `ZeroSizeWithPhantomData`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:106:40
--> $DIR/lint-ctypes-fn.rs:110:40
|
LL | pub extern "C" fn zero_size_phantom(p: ZeroSizeWithPhantomData) { }
| ^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
Expand All @@ -116,15 +116,15 @@ LL | pub struct ZeroSizeWithPhantomData(PhantomData<i32>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `PhantomData<bool>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:109:51
--> $DIR/lint-ctypes-fn.rs:113:51
|
LL | pub extern "C" fn zero_size_phantom_toplevel() -> PhantomData<bool> {
| ^^^^^^^^^^^^^^^^^ not FFI-safe
|
= note: composed only of `PhantomData`

error: `extern` fn uses type `fn()`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:114:30
--> $DIR/lint-ctypes-fn.rs:118:30
|
LL | pub extern "C" fn fn_type(p: RustFn) { }
| ^^^^^^ not FFI-safe
Expand All @@ -133,7 +133,7 @@ LL | pub extern "C" fn fn_type(p: RustFn) { }
= note: this function pointer has Rust-specific calling convention

error: `extern` fn uses type `fn()`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:117:31
--> $DIR/lint-ctypes-fn.rs:121:31
|
LL | pub extern "C" fn fn_type2(p: fn()) { }
| ^^^^ not FFI-safe
Expand All @@ -142,15 +142,15 @@ LL | pub extern "C" fn fn_type2(p: fn()) { }
= note: this function pointer has Rust-specific calling convention

error: `extern` fn uses type `i128`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:122:39
--> $DIR/lint-ctypes-fn.rs:126:39
|
LL | pub extern "C" fn transparent_i128(p: TransparentI128) { }
| ^^^^^^^^^^^^^^^ not FFI-safe
|
= note: 128-bit integers don't currently have a known stable ABI

error: `extern` fn uses type `str`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:125:38
--> $DIR/lint-ctypes-fn.rs:129:38
|
LL | pub extern "C" fn transparent_str(p: TransparentStr) { }
| ^^^^^^^^^^^^^^ not FFI-safe
Expand All @@ -159,15 +159,15 @@ LL | pub extern "C" fn transparent_str(p: TransparentStr) { }
= note: string slices have no C equivalent

error: `extern` fn uses type `PhantomData<bool>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:171:43
--> $DIR/lint-ctypes-fn.rs:175:43
|
LL | pub extern "C" fn unused_generic2<T>() -> PhantomData<bool> {
| ^^^^^^^^^^^^^^^^^ not FFI-safe
|
= note: composed only of `PhantomData`

error: `extern` fn uses type `Vec<T>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:184:39
--> $DIR/lint-ctypes-fn.rs:188:39
|
LL | pub extern "C" fn used_generic4<T>(x: Vec<T>) { }
| ^^^^^^ not FFI-safe
Expand All @@ -176,7 +176,7 @@ LL | pub extern "C" fn used_generic4<T>(x: Vec<T>) { }
= note: this struct has unspecified layout

error: `extern` fn uses type `Vec<T>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:187:41
--> $DIR/lint-ctypes-fn.rs:191:41
|
LL | pub extern "C" fn used_generic5<T>() -> Vec<T> {
| ^^^^^^ not FFI-safe
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2 changes: 2 additions & 0 deletions src/test/ui/lint/lint-ctypes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,8 @@ pub struct ZeroSizeWithPhantomData(::std::marker::PhantomData<i32>);
extern "C" {
pub fn ptr_type1(size: *const Foo); //~ ERROR: uses type `Foo`
pub fn ptr_type2(size: *const Foo); //~ ERROR: uses type `Foo`
pub fn ptr_unit(p: *const ());
pub fn ptr_tuple(p: *const ((),)); //~ ERROR: uses type `((),)`
pub fn slice_type(p: &[u32]); //~ ERROR: uses type `[u32]`
pub fn str_type(p: &str); //~ ERROR: uses type `str`
pub fn box_type(p: Box<u32>); //~ ERROR uses type `Box<u32>`
Expand Down
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