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Warn against boxed DST in improper_ctypes_definitions lint
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@marmeladema
marmeladema committed Jun 3, 2021
1 parent 2577825 commit 877cfb1
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Showing 3 changed files with 66 additions and 24 deletions.
15 changes: 11 additions & 4 deletions compiler/rustc_lint/src/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -909,11 +909,18 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
}

match *ty.kind() {
ty::Adt(def, _) if def.is_box() && matches!(self.mode, CItemKind::Definition) => {
FfiSafe
}

ty::Adt(def, substs) => {
if def.is_box() && matches!(self.mode, CItemKind::Definition) {
if ty.boxed_ty().is_sized(tcx.at(DUMMY_SP), self.cx.param_env) {
return FfiSafe;
} else {
return FfiUnsafe {
ty,
reason: format!("box cannot be represented as a single pointer"),
help: None,
};
}
}
if def.is_phantom_data() {
return FfiPhantom(ty);
}
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11 changes: 11 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 @@ -8,6 +8,8 @@ extern crate libc;
use std::default::Default;
use std::marker::PhantomData;

trait Trait {}

trait Mirror { type It: ?Sized; }

impl<T: ?Sized> Mirror for T { type It = Self; }
Expand Down Expand Up @@ -74,6 +76,15 @@ pub extern "C" fn box_type(p: Box<u32>) { }

pub extern "C" fn opt_box_type(p: Option<Box<u32>>) { }

pub extern "C" fn boxed_slice(p: Box<[u8]>) { }
//~^ ERROR: uses type `Box<[u8]>`

pub extern "C" fn boxed_string(p: Box<str>) { }
//~^ ERROR: uses type `Box<str>`

pub extern "C" fn boxed_trait(p: Box<dyn Trait>) { }
//~^ ERROR: uses type `Box<dyn Trait>`

pub extern "C" fn char_type(p: char) { }
//~^ ERROR uses type `char`

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64 changes: 44 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:67:33
--> $DIR/lint-ctypes-fn.rs:69:33
|
LL | pub extern "C" fn slice_type(p: &[u32]) { }
| ^^^^^^ not FFI-safe
Expand All @@ -13,16 +13,40 @@ 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:70:31
--> $DIR/lint-ctypes-fn.rs:72:31
|
LL | pub extern "C" fn str_type(p: &str) { }
| ^^^^ not FFI-safe
|
= help: consider using `*const u8` and a length instead
= 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
|
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
|
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
|
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:77:32
--> $DIR/lint-ctypes-fn.rs:88:32
|
LL | pub extern "C" fn char_type(p: char) { }
| ^^^^ not FFI-safe
Expand All @@ -31,23 +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:80:32
--> $DIR/lint-ctypes-fn.rs:91:32
|
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:83:32
--> $DIR/lint-ctypes-fn.rs:94:32
|
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:86:33
--> $DIR/lint-ctypes-fn.rs:97:33
|
LL | pub extern "C" fn tuple_type(p: (i32, i32)) { }
| ^^^^^^^^^^ not FFI-safe
Expand All @@ -56,7 +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:89:34
--> $DIR/lint-ctypes-fn.rs:100:34
|
LL | pub extern "C" fn tuple_type2(p: I32Pair) { }
| ^^^^^^^ not FFI-safe
Expand All @@ -65,42 +89,42 @@ 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:92:32
--> $DIR/lint-ctypes-fn.rs:103:32
|
LL | pub extern "C" fn zero_size(p: ZeroSize) { }
| ^^^^^^^^ not FFI-safe
|
= help: consider adding a member to this struct
= note: this struct has no fields
note: the type is defined here
--> $DIR/lint-ctypes-fn.rs:26:1
--> $DIR/lint-ctypes-fn.rs:28:1
|
LL | pub struct ZeroSize;
| ^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `ZeroSizeWithPhantomData`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:95:40
--> $DIR/lint-ctypes-fn.rs:106:40
|
LL | pub extern "C" fn zero_size_phantom(p: ZeroSizeWithPhantomData) { }
| ^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
|
= note: composed only of `PhantomData`
note: the type is defined here
--> $DIR/lint-ctypes-fn.rs:61:1
--> $DIR/lint-ctypes-fn.rs:63:1
|
LL | pub struct ZeroSizeWithPhantomData(PhantomData<i32>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `PhantomData<bool>`, which is not FFI-safe
--> $DIR/lint-ctypes-fn.rs:98:51
--> $DIR/lint-ctypes-fn.rs:109:51
|
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:103:30
--> $DIR/lint-ctypes-fn.rs:114:30
|
LL | pub extern "C" fn fn_type(p: RustFn) { }
| ^^^^^^ not FFI-safe
Expand All @@ -109,7 +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:106:31
--> $DIR/lint-ctypes-fn.rs:117:31
|
LL | pub extern "C" fn fn_type2(p: fn()) { }
| ^^^^ not FFI-safe
Expand All @@ -118,15 +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:111:39
--> $DIR/lint-ctypes-fn.rs:122:39
|
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:114:38
--> $DIR/lint-ctypes-fn.rs:125:38
|
LL | pub extern "C" fn transparent_str(p: TransparentStr) { }
| ^^^^^^^^^^^^^^ not FFI-safe
Expand All @@ -135,15 +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:160:43
--> $DIR/lint-ctypes-fn.rs:171:43
|
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:173:39
--> $DIR/lint-ctypes-fn.rs:184:39
|
LL | pub extern "C" fn used_generic4<T>(x: Vec<T>) { }
| ^^^^^^ not FFI-safe
Expand All @@ -152,13 +176,13 @@ 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:176:41
--> $DIR/lint-ctypes-fn.rs:187:41
|
LL | pub extern "C" fn used_generic5<T>() -> Vec<T> {
| ^^^^^^ not FFI-safe
|
= help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
= note: this struct has unspecified layout

error: aborting due to 17 previous errors
error: aborting due to 20 previous errors

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