Rustup

rust-version

@@ -1 +1 @@
-008c21c9779fd1e3632d9fe908b8afc0c421b26c
+dca2d1ff00bf96d244b1bb9a2117a92ec50ac71d

tests/fail/function_pointers/abi_mismatch_array_vs_struct.rs

@@ -0,0 +1,16 @@
+#![feature(portable_simd)]
+
+// Some targets treat arrays and structs very differently. We would probably catch that on those
+// targets since we check the `PassMode`; here we ensure that we catch it on *all* targets
+// (in particular, on x86-64 the pass mode is `Indirect` for both of these).
+struct S(i32, i32, i32, i32);
+type A = [i32; 4];
+
+fn main() {
+    fn f(_: S) {}
+
+    // These two types have the same size but are still not compatible.
+    let g = unsafe { std::mem::transmute::<fn(S), fn(A)>(f) };
+
+    g(Default::default()) //~ ERROR: calling a function with argument of type S passing data of type [i32; 4]
+}

tests/fail/function_pointers/abi_mismatch_array_vs_struct.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: calling a function with argument of type S passing data of type [i32; 4]
+  --> $DIR/abi_mismatch_array_vs_struct.rs:LL:CC
+   |
+LL |     g(Default::default())
+   |     ^^^^^^^^^^^^^^^^^^^^^ calling a function with argument of type S passing data of type [i32; 4]
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/abi_mismatch_array_vs_struct.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to previous error
+

tests/fail/function_pointers/abi_mismatch_int_vs_float.rs

@@ -0,0 +1,7 @@
+fn main() {
+    fn f(_: f32) {}
+
+    let g = unsafe { std::mem::transmute::<fn(f32), fn(i32)>(f) };
+
+    g(42) //~ ERROR: calling a function with argument of type f32 passing data of type i32
+}

tests/fail/function_pointers/abi_mismatch_int_vs_float.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: calling a function with argument of type f32 passing data of type i32
+  --> $DIR/abi_mismatch_int_vs_float.rs:LL:CC
+   |
+LL |     g(42)
+   |     ^^^^^ calling a function with argument of type f32 passing data of type i32
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/abi_mismatch_int_vs_float.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to previous error
+

tests/fail/function_pointers/cast_fn_ptr4.stderr → tests/fail/function_pointers/abi_mismatch_raw_pointer.stderr

@@ -1,13 +1,13 @@
 error: Undefined Behavior: calling a function with argument of type *const [i32] passing data of type *const i32
-  --> $DIR/cast_fn_ptr4.rs:LL:CC
+  --> $DIR/abi_mismatch_raw_pointer.rs:LL:CC
    |
 LL |     g(&42 as *const i32)
    |     ^^^^^^^^^^^^^^^^^^^^ calling a function with argument of type *const [i32] passing data of type *const i32
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/cast_fn_ptr4.rs:LL:CC
+   = note: inside `main` at $DIR/abi_mismatch_raw_pointer.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/function_pointers/cast_fn_ptr5.stderr → tests/fail/function_pointers/abi_mismatch_return_type.stderr

@@ -1,13 +1,13 @@
 error: Undefined Behavior: calling a function with return type u32 passing return place of type ()
-  --> $DIR/cast_fn_ptr5.rs:LL:CC
+  --> $DIR/abi_mismatch_return_type.rs:LL:CC
    |
 LL |     g()
    |     ^^^ calling a function with return type u32 passing return place of type ()
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/cast_fn_ptr5.rs:LL:CC
+   = note: inside `main` at $DIR/abi_mismatch_return_type.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/function_pointers/cast_fn_ptr2.stderr → tests/fail/function_pointers/abi_mismatch_simple.stderr

@@ -1,13 +1,13 @@
 error: Undefined Behavior: calling a function with argument of type (i32, i32) passing data of type i32
-  --> $DIR/cast_fn_ptr2.rs:LL:CC
+  --> $DIR/abi_mismatch_simple.rs:LL:CC
    |
 LL |     g(42)
    |     ^^^^^ calling a function with argument of type (i32, i32) passing data of type i32
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/cast_fn_ptr2.rs:LL:CC
+   = note: inside `main` at $DIR/abi_mismatch_simple.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/function_pointers/cast_fn_ptr3.stderr → tests/fail/function_pointers/abi_mismatch_too_few_args.stderr

@@ -1,13 +1,13 @@
 error: Undefined Behavior: calling a function with fewer arguments than it requires
-  --> $DIR/cast_fn_ptr3.rs:LL:CC
+  --> $DIR/abi_mismatch_too_few_args.rs:LL:CC
    |
 LL |     g()
    |     ^^^ calling a function with fewer arguments than it requires
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/cast_fn_ptr3.rs:LL:CC
+   = note: inside `main` at $DIR/abi_mismatch_too_few_args.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/function_pointers/cast_fn_ptr1.stderr → tests/fail/function_pointers/abi_mismatch_too_many_args.stderr

@@ -1,13 +1,13 @@
 error: Undefined Behavior: calling a function with more arguments than it expected
-  --> $DIR/cast_fn_ptr1.rs:LL:CC
+  --> $DIR/abi_mismatch_too_many_args.rs:LL:CC
    |
 LL |     g(42)
    |     ^^^^^ calling a function with more arguments than it expected
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
-   = note: inside `main` at $DIR/cast_fn_ptr1.rs:LL:CC
+   = note: inside `main` at $DIR/abi_mismatch_too_many_args.rs:LL:CC
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 

tests/fail/function_pointers/abi_mismatch_vector.rs

@@ -0,0 +1,11 @@
+#![feature(portable_simd)]
+use std::simd;
+
+fn main() {
+    fn f(_: simd::u32x8) {}
+
+    // These two vector types have the same size but are still not compatible.
+    let g = unsafe { std::mem::transmute::<fn(simd::u32x8), fn(simd::u64x4)>(f) };
+
+    g(Default::default()) //~ ERROR: calling a function with argument of type std::simd::Simd<u32, 8> passing data of type std::simd::Simd<u64, 4>
+}

tests/fail/function_pointers/abi_mismatch_vector.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: calling a function with argument of type std::simd::Simd<u32, 8> passing data of type std::simd::Simd<u64, 4>
+  --> $DIR/abi_mismatch_vector.rs:LL:CC
+   |
+LL |     g(Default::default())
+   |     ^^^^^^^^^^^^^^^^^^^^^ calling a function with argument of type std::simd::Simd<u32, 8> passing data of type std::simd::Simd<u64, 4>
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/abi_mismatch_vector.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to previous error
+

tests/pass/function_calls/abi_compat.rs

@@ -1,29 +1,91 @@
+#![feature(portable_simd)]
 use std::mem;
 use std::num;
+use std::simd;
 
-fn test_abi_compat<T, U>(t: T, u: U) {
+#[derive(Copy, Clone)]
+struct Zst;
+
+fn test_abi_compat<T: Copy, U: Copy>(t: T, u: U) {
     fn id<T>(x: T) -> T {
         x
     }
+    extern "C" fn id_c<T>(x: T) -> T {
+        x
+    }
 
     // This checks ABI compatibility both for arguments and return values,
     // in both directions.
     let f: fn(T) -> T = id;
     let f: fn(U) -> U = unsafe { std::mem::transmute(f) };
-    drop(f(u));
-
+    let _val = f(u);
     let f: fn(U) -> U = id;
     let f: fn(T) -> T = unsafe { std::mem::transmute(f) };
-    drop(f(t));
+    let _val = f(t);
+
+    // And then we do the same for `extern "C"`.
+    let f: extern "C" fn(T) -> T = id_c;
+    let f: extern "C" fn(U) -> U = unsafe { std::mem::transmute(f) };
+    let _val = f(u);
+    let f: extern "C" fn(U) -> U = id_c;
+    let f: extern "C" fn(T) -> T = unsafe { std::mem::transmute(f) };
+    let _val = f(t);
+}
+
+/// Ensure that `T` is compatible with various repr(transparent) wrappers around `T`.
+fn test_abi_newtype<T: Copy>(t: T) {
+    #[repr(transparent)]
+    #[derive(Copy, Clone)]
+    struct Wrapper1<T>(T);
+    #[repr(transparent)]
+    #[derive(Copy, Clone)]
+    struct Wrapper2<T>(T, ());
+    #[repr(transparent)]
+    #[derive(Copy, Clone)]
+    struct Wrapper2a<T>((), T);
+    #[repr(transparent)]
+    #[derive(Copy, Clone)]
+    struct Wrapper3<T>(Zst, T, [u8; 0]);
+
+    test_abi_compat(t, Wrapper1(t));
+    test_abi_compat(t, Wrapper2(t, ()));
+    test_abi_compat(t, Wrapper2a((), t));
+    test_abi_compat(t, Wrapper3(Zst, t, []));
+    test_abi_compat(t, mem::MaybeUninit::new(t)); // MaybeUninit is `repr(transparent)`
 }
 
 fn main() {
+    // Here we check:
+    // - unsigned vs signed integer is allowed
+    // - u32/i32 vs char is allowed
+    // - u32 vs NonZeroU32/Option<NonZeroU32> is allowed
+    // - reference vs raw pointer is allowed
+    // - references to things of the same size and alignment are allowed
+    // These are very basic tests that should work on all ABIs. However it is not clear that any of
+    // these would be stably guaranteed. Code that relies on this is equivalent to code that relies
+    // on the layout of `repr(Rust)` types. They are also fragile: the same mismatches in the fields
+    // of a struct (even with `repr(C)`) will not always be accepted by Miri.
+    test_abi_compat(0u32, 0i32);
+    test_abi_compat(simd::u32x8::splat(1), simd::i32x8::splat(1));
     test_abi_compat(0u32, 'x');
-    test_abi_compat(&0u32, &([true; 4], [0u32; 0]));
-    test_abi_compat(0u32, mem::MaybeUninit::new(0u32));
+    test_abi_compat(0i32, 'x');
     test_abi_compat(42u32, num::NonZeroU32::new(1).unwrap());
     test_abi_compat(0u32, Some(num::NonZeroU32::new(1).unwrap()));
-    test_abi_compat(0u32, 0i32);
-    // Note that `bool` and `u8` are *not* compatible!
+    test_abi_compat(&0u32, &0u32 as *const u32);
+    test_abi_compat(&0u32, &([true; 4], [0u32; 0]));
+    // Note that `bool` and `u8` are *not* compatible, at least on x86-64!
     // One of them has `arg_ext: Zext`, the other does not.
+
+    // These must work for *any* type, since we guarantee that `repr(transparent)` is ABI-compatible
+    // with the wrapped field.
+    test_abi_newtype(());
+    // FIXME: this still fails! test_abi_newtype(Zst);
+    test_abi_newtype(0u32);
+    test_abi_newtype(0f32);
+    test_abi_newtype((0u32, 1u32, 2u32));
+    // FIXME: skipping the array tests on mips64 due to https://github.com/rust-lang/rust/issues/115404
+    if !cfg!(target_arch = "mips64") {
+        test_abi_newtype([0u32, 1u32, 2u32]);
+        test_abi_newtype([0i32; 0]);
+    }
 }