improper_ctypes: allow pointers to sized types

This commit changes the improper ctypes lint (when operating on definitions) to consider raw pointers or references to sized types as FFI-safe. Signed-off-by: David Wood <david@davidtw.co>
rust-lang · Jun 24, 2020 · 5c86348 · 5c86348
1 parent 14ea7a7
commit 5c86348
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Showing 3 changed files with 34 additions and 85 deletions.
diff --git a/src/librustc_lint/types.rs b/src/librustc_lint/types.rs
@@ -14,7 +14,7 @@ use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt, TypeFoldable};
 use rustc_span::source_map;
 use rustc_span::symbol::sym;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{Integer, LayoutOf, TagEncoding, VariantIdx, Variants};
 use rustc_target::spec::abi::Abi;
 
@@ -818,6 +818,15 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                 help: Some("consider using a struct instead".into()),
             },
 
+            ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _)
+                if {
+                    matches!(self.mode, ImproperCTypesMode::Definitions)
+                        && ty.is_sized(self.cx.tcx.at(DUMMY_SP), self.cx.param_env)
+                } =>
+            {
+                FfiSafe
+            }
+
             ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
                 self.check_type_for_ffi(cache, ty)
             }

diff --git a/src/test/ui/lint/lint-ctypes-fn.rs b/src/test/ui/lint/lint-ctypes-fn.rs
@@ -61,10 +61,8 @@ pub struct TransparentCustomZst(i32, ZeroSize);
 pub struct ZeroSizeWithPhantomData(PhantomData<i32>);
 
 pub extern "C" fn ptr_type1(size: *const Foo) { }
-//~^ ERROR: uses type `Foo`
 
 pub extern "C" fn ptr_type2(size: *const Foo) { }
-//~^ ERROR: uses type `Foo`
 
 pub extern "C" fn slice_type(p: &[u32]) { }
 //~^ ERROR: uses type `[u32]`
@@ -159,7 +157,6 @@ pub extern "C" fn good1(size: *const libc::c_int) { }
 pub extern "C" fn good2(size: *const libc::c_uint) { }
 
 pub extern "C" fn unused_generic1<T>(size: *const Foo) { }
-//~^ ERROR: uses type `Foo`
 
 pub extern "C" fn unused_generic2<T>() -> PhantomData<bool> {
 //~^ ERROR uses type `std::marker::PhantomData<bool>`
@@ -169,7 +166,6 @@ pub extern "C" fn unused_generic2<T>() -> PhantomData<bool> {
 pub extern "C" fn used_generic1<T>(x: T) { }
 
 pub extern "C" fn used_generic2<T>(x: T, size: *const Foo) { }
-//~^ ERROR: uses type `Foo`
 
 pub extern "C" fn used_generic3<T: Default>() -> T {
     Default::default()

diff --git a/src/test/ui/lint/lint-ctypes-fn.stderr b/src/test/ui/lint/lint-ctypes-fn.stderr
@@ -1,47 +1,19 @@
-error: `extern` fn uses type `Foo`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:63:35
+error: `extern` fn uses type `[u32]`, which is not FFI-safe
+  --> $DIR/lint-ctypes-fn.rs:67:33
    |
-LL | pub extern "C" fn ptr_type1(size: *const Foo) { }
-   |                                   ^^^^^^^^^^ not FFI-safe
+LL | pub extern "C" fn slice_type(p: &[u32]) { }
+   |                                 ^^^^^^ not FFI-safe
    |
 note: the lint level is defined here
   --> $DIR/lint-ctypes-fn.rs:4:9
    |
 LL | #![deny(improper_ctypes_definitions)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
-   = note: this struct has unspecified layout
-note: the type is defined here
-  --> $DIR/lint-ctypes-fn.rs:34:1
-   |
-LL | pub struct Foo;
-   | ^^^^^^^^^^^^^^^
-
-error: `extern` fn uses type `Foo`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:66:35
-   |
-LL | pub extern "C" fn ptr_type2(size: *const Foo) { }
-   |                                   ^^^^^^^^^^ not FFI-safe
-   |
-   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
-   = note: this struct has unspecified layout
-note: the type is defined here
-  --> $DIR/lint-ctypes-fn.rs:34:1
-   |
-LL | pub struct Foo;
-   | ^^^^^^^^^^^^^^^
-
-error: `extern` fn uses type `[u32]`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:69:33
-   |
-LL | pub extern "C" fn slice_type(p: &[u32]) { }
-   |                                 ^^^^^^ not FFI-safe
-   |
    = help: consider using a raw pointer instead
    = 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:70:31
    |
 LL | pub extern "C" fn str_type(p: &str) { }
    |                               ^^^^ not FFI-safe
@@ -50,7 +22,7 @@ LL | pub extern "C" fn str_type(p: &str) { }
    = note: string slices have no C equivalent
 
 error: `extern` fn uses type `std::boxed::Box<u32>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:75:31
+  --> $DIR/lint-ctypes-fn.rs:73:31
    |
 LL | pub extern "C" fn box_type(p: Box<u32>) { }
    |                               ^^^^^^^^ not FFI-safe
@@ -59,7 +31,7 @@ LL | pub extern "C" fn box_type(p: Box<u32>) { }
    = note: this struct has unspecified layout
 
 error: `extern` fn uses type `char`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:78:32
+  --> $DIR/lint-ctypes-fn.rs:76:32
    |
 LL | pub extern "C" fn char_type(p: char) { }
    |                                ^^^^ not FFI-safe
@@ -68,23 +40,23 @@ 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:81:32
+  --> $DIR/lint-ctypes-fn.rs:79:32
    |
 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:84:32
+  --> $DIR/lint-ctypes-fn.rs:82:32
    |
 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:87:33
+  --> $DIR/lint-ctypes-fn.rs:85:33
    |
 LL | pub extern "C" fn tuple_type(p: (i32, i32)) { }
    |                                 ^^^^^^^^^^ not FFI-safe
@@ -93,7 +65,7 @@ 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:90:34
+  --> $DIR/lint-ctypes-fn.rs:88:34
    |
 LL | pub extern "C" fn tuple_type2(p: I32Pair) { }
    |                                  ^^^^^^^ not FFI-safe
@@ -102,7 +74,7 @@ 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:93:32
+  --> $DIR/lint-ctypes-fn.rs:91:32
    |
 LL | pub extern "C" fn zero_size(p: ZeroSize) { }
    |                                ^^^^^^^^ not FFI-safe
@@ -116,7 +88,7 @@ LL | pub struct ZeroSize;
    | ^^^^^^^^^^^^^^^^^^^^
 
 error: `extern` fn uses type `ZeroSizeWithPhantomData`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:96:40
+  --> $DIR/lint-ctypes-fn.rs:94:40
    |
 LL | pub extern "C" fn zero_size_phantom(p: ZeroSizeWithPhantomData) { }
    |                                        ^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -129,15 +101,15 @@ LL | pub struct ZeroSizeWithPhantomData(PhantomData<i32>);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `extern` fn uses type `std::marker::PhantomData<bool>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:99:51
+  --> $DIR/lint-ctypes-fn.rs:97:51
    |
 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:104:30
+  --> $DIR/lint-ctypes-fn.rs:102:30
    |
 LL | pub extern "C" fn fn_type(p: RustFn) { }
    |                              ^^^^^^ not FFI-safe
@@ -146,7 +118,7 @@ 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:107:31
+  --> $DIR/lint-ctypes-fn.rs:105:31
    |
 LL | pub extern "C" fn fn_type2(p: fn()) { }
    |                               ^^^^ not FFI-safe
@@ -155,7 +127,7 @@ LL | pub extern "C" fn fn_type2(p: fn()) { }
    = note: this function pointer has Rust-specific calling convention
 
 error: `extern` fn uses type `std::boxed::Box<u32>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:110:35
+  --> $DIR/lint-ctypes-fn.rs:108:35
    |
 LL | pub extern "C" fn fn_contained(p: RustBadRet) { }
    |                                   ^^^^^^^^^^ not FFI-safe
@@ -164,15 +136,15 @@ LL | pub extern "C" fn fn_contained(p: RustBadRet) { }
    = note: this struct has unspecified layout
 
 error: `extern` fn uses type `i128`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:113:39
+  --> $DIR/lint-ctypes-fn.rs:111:39
    |
 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:116:38
+  --> $DIR/lint-ctypes-fn.rs:114:38
    |
 LL | pub extern "C" fn transparent_str(p: TransparentStr) { }
    |                                      ^^^^^^^^^^^^^^ not FFI-safe
@@ -181,52 +153,24 @@ LL | pub extern "C" fn transparent_str(p: TransparentStr) { }
    = note: string slices have no C equivalent
 
 error: `extern` fn uses type `std::boxed::Box<u32>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:119:37
+  --> $DIR/lint-ctypes-fn.rs:117:37
    |
 LL | pub extern "C" fn transparent_fn(p: TransparentBadFn) { }
    |                                     ^^^^^^^^^^^^^^^^ not FFI-safe
    |
    = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
    = note: this struct has unspecified layout
 
-error: `extern` fn uses type `Foo`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:161:44
-   |
-LL | pub extern "C" fn unused_generic1<T>(size: *const Foo) { }
-   |                                            ^^^^^^^^^^ not FFI-safe
-   |
-   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
-   = note: this struct has unspecified layout
-note: the type is defined here
-  --> $DIR/lint-ctypes-fn.rs:34:1
-   |
-LL | pub struct Foo;
-   | ^^^^^^^^^^^^^^^
-
 error: `extern` fn uses type `std::marker::PhantomData<bool>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:164:43
+  --> $DIR/lint-ctypes-fn.rs:161:43
    |
 LL | pub extern "C" fn unused_generic2<T>() -> PhantomData<bool> {
    |                                           ^^^^^^^^^^^^^^^^^ not FFI-safe
    |
    = note: composed only of `PhantomData`
 
-error: `extern` fn uses type `Foo`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:171:48
-   |
-LL | pub extern "C" fn used_generic2<T>(x: T, size: *const Foo) { }
-   |                                                ^^^^^^^^^^ not FFI-safe
-   |
-   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
-   = note: this struct has unspecified layout
-note: the type is defined here
-  --> $DIR/lint-ctypes-fn.rs:34:1
-   |
-LL | pub struct Foo;
-   | ^^^^^^^^^^^^^^^
-
 error: `extern` fn uses type `std::vec::Vec<T>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:178:39
+  --> $DIR/lint-ctypes-fn.rs:174:39
    |
 LL | pub extern "C" fn used_generic4<T>(x: Vec<T>) { }
    |                                       ^^^^^^ not FFI-safe
@@ -235,13 +179,13 @@ LL | pub extern "C" fn used_generic4<T>(x: Vec<T>) { }
    = note: this struct has unspecified layout
 
 error: `extern` fn uses type `std::vec::Vec<T>`, which is not FFI-safe
-  --> $DIR/lint-ctypes-fn.rs:181:41
+  --> $DIR/lint-ctypes-fn.rs:177:41
    |
 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 24 previous errors
+error: aborting due to 20 previous errors