Rollup merge of #144535 - RalfJung:abi-mismatch-err, r=compiler-errors

miri: for ABI mismatch errors, say which argument is the problem

Author: matthiaskrgr

src/diagnostics.rs

@@ -382,7 +382,7 @@ pub fn report_error<'tcx>(
                             helps.push(note_span!(span, "{:?} was deallocated here:", alloc_id));
                         }
                     }
-                    AbiMismatchArgument { .. } | AbiMismatchReturn { .. } => {
+                    AbiMismatchArgument { .. } => {
                         helps.push(note!("this means these two types are not *guaranteed* to be ABI-compatible across all targets"));
                         helps.push(note!("if you think this code should be accepted anyway, please report an issue with Miri"));
                     }

src/helpers.rs

@@ -1079,6 +1079,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             .position(|b| !b)
         {
             throw_ub!(AbiMismatchArgument {
+                arg_idx: index,
                 caller_ty: caller_fn_abi.args[index].layout.ty,
                 callee_ty: callee_fn_abi.args[index].layout.ty
             });

tests/fail/function_pointers/abi_mismatch_array_vs_struct.rs

@@ -17,5 +17,5 @@ fn main() {
     // 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]
+    g(Default::default()) //~ ERROR: type S passing argument of type [i32; 4]
 }

tests/fail/function_pointers/abi_mismatch_array_vs_struct.stderr

@@ -1,4 +1,4 @@
-error: Undefined Behavior: calling a function with argument of type S passing data of type [i32; 4]
+error: Undefined Behavior: calling a function whose parameter #1 has type S passing argument of type [i32; 4]
   --> tests/fail/function_pointers/abi_mismatch_array_vs_struct.rs:LL:CC
    |
 LL |     g(Default::default())

tests/fail/function_pointers/abi_mismatch_int_vs_float.rs

@@ -3,5 +3,5 @@ fn main() {
 
     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
+    g(42) //~ ERROR: type f32 passing argument of type i32
 }

tests/fail/function_pointers/abi_mismatch_int_vs_float.stderr

@@ -1,4 +1,4 @@
-error: Undefined Behavior: calling a function with argument of type f32 passing data of type i32
+error: Undefined Behavior: calling a function whose parameter #1 has type f32 passing argument of type i32
   --> tests/fail/function_pointers/abi_mismatch_int_vs_float.rs:LL:CC
    |
 LL |     g(42)

tests/fail/function_pointers/abi_mismatch_raw_pointer.rs

@@ -3,5 +3,5 @@ fn main() {
 
     let g = unsafe { std::mem::transmute::<fn(*const [i32]), fn(*const i32)>(f) };
 
-    g(&42 as *const i32) //~ ERROR: calling a function with argument of type *const [i32] passing data of type *const i32
+    g(&42 as *const i32) //~ ERROR: type *const [i32] passing argument of type *const i32
 }

tests/fail/function_pointers/abi_mismatch_raw_pointer.stderr

@@ -1,4 +1,4 @@
-error: Undefined Behavior: calling a function with argument of type *const [i32] passing data of type *const i32
+error: Undefined Behavior: calling a function whose parameter #1 has type *const [i32] passing argument of type *const i32
   --> tests/fail/function_pointers/abi_mismatch_raw_pointer.rs:LL:CC
    |
 LL |     g(&42 as *const i32)

tests/fail/function_pointers/abi_mismatch_repr_C.rs

@@ -12,5 +12,5 @@ fn main() {
     let fnptr: fn(S2) = callee;
     let fnptr: fn(S1) = unsafe { std::mem::transmute(fnptr) };
     fnptr(S1(NonZero::new(1).unwrap()));
-    //~^ ERROR: calling a function with argument of type S2 passing data of type S1
+    //~^ ERROR: type S2 passing argument of type S1
 }

tests/fail/function_pointers/abi_mismatch_repr_C.stderr

@@ -1,4 +1,4 @@
-error: Undefined Behavior: calling a function with argument of type S2 passing data of type S1
+error: Undefined Behavior: calling a function whose parameter #1 has type S2 passing argument of type S1
   --> tests/fail/function_pointers/abi_mismatch_repr_C.rs:LL:CC
    |
 LL |     fnptr(S1(NonZero::new(1).unwrap()));