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Auto merge of #148302 - folkertdev:non-rustic-unsized, r=bjorn3
error on non-rustic ABIs using unsized parameters tracking issue: #48055 This came up in #144529 (comment). The idea is that the layout of an unsized type is unstable (following the rust layout rules), and hence stable ABIs should not use unsized types. On stable, unsized types (or generics with a `?Sized` bound) are not accepted as parameters, so the errors introduced by this PR can only be observed when the unstable `unsized_fn_params` feature is enabled. r? `@bjorn3` cc `@RalfJung`
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‎compiler/rustc_abi/src/canon_abi.rs‎

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@@ -51,6 +51,20 @@ pub enum CanonAbi {
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X86(X86Call),
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}
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impl CanonAbi {
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pub fn is_rustic_abi(self) -> bool {
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match self {
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CanonAbi::Rust | CanonAbi::RustCold => true,
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CanonAbi::C
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| CanonAbi::Custom
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| CanonAbi::Arm(_)
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| CanonAbi::GpuKernel
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| CanonAbi::Interrupt(_)
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| CanonAbi::X86(_) => false,
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}
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}
66+
}
67+
5468
impl fmt::Display for CanonAbi {
5569
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
5670
// convert to the ExternAbi that *shares a string* with this CanonAbi.

‎compiler/rustc_monomorphize/messages.ftl‎

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@@ -12,6 +12,17 @@ monomorphize_abi_error_disabled_vector_type =
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} here
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.help = consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable="{$required_feature}")]`)
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monomorphize_abi_error_unsupported_unsized_parameter =
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this function {$is_call ->
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[true] call
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*[false] definition
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} uses unsized type `{$ty}` which is not supported with the chosen ABI
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.label = function {$is_call ->
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[true] called
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*[false] defined
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} here
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.help = only rustic ABIs support unsized parameters
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1526
monomorphize_abi_error_unsupported_vector_type =
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this function {$is_call ->
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[true] call

‎compiler/rustc_monomorphize/src/errors.rs‎

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@@ -80,6 +80,18 @@ pub(crate) struct AbiErrorDisabledVectorType<'a> {
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pub is_call: bool,
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}
8282

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#[derive(Diagnostic)]
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#[diag(monomorphize_abi_error_unsupported_unsized_parameter)]
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#[help]
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pub(crate) struct AbiErrorUnsupportedUnsizedParameter<'a> {
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#[primary_span]
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#[label]
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pub span: Span,
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pub ty: Ty<'a>,
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/// Whether this is a problem at a call site or at a declaration.
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pub is_call: bool,
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}
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#[derive(Diagnostic)]
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#[diag(monomorphize_abi_error_unsupported_vector_type)]
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pub(crate) struct AbiErrorUnsupportedVectorType<'a> {

‎compiler/rustc_monomorphize/src/mono_checks/abi_check.rs‎

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Original file line numberDiff line numberDiff line change
@@ -78,8 +78,37 @@ fn do_check_simd_vector_abi<'tcx>(
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}
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}
8080

81-
/// Checks that the ABI of a given instance of a function does not contain vector-passed arguments
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/// or return values for which the corresponding target feature is not enabled.
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/// Emit an error when a non-rustic ABI has unsized parameters.
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/// Unsized types do not have a stable layout, so should not be used with stable ABIs.
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/// `is_call` indicates whether this is a call-site check or a definition-site check;
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/// this is only relevant for the wording in the emitted error.
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fn do_check_unsized_params<'tcx>(
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tcx: TyCtxt<'tcx>,
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fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
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is_call: bool,
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loc: impl Fn() -> (Span, HirId),
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) {
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// Unsized parameters are allowed with the (unstable) "Rust" (and similar) ABIs.
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if fn_abi.conv.is_rustic_abi() {
93+
return;
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}
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96+
for arg_abi in fn_abi.args.iter() {
97+
if !arg_abi.layout.layout.is_sized() {
98+
let (span, _hir_id) = loc();
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tcx.dcx().emit_err(errors::AbiErrorUnsupportedUnsizedParameter {
100+
span,
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ty: arg_abi.layout.ty,
102+
is_call,
103+
});
104+
}
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}
106+
}
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108+
/// Checks the ABI of an Instance, emitting an error when:
109+
///
110+
/// - a non-rustic ABI uses unsized parameters
111+
/// - the signature requires target features that are not enabled
83112
fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
84113
let typing_env = ty::TypingEnv::fully_monomorphized();
85114
let Ok(abi) = tcx.fn_abi_of_instance(typing_env.as_query_input((instance, ty::List::empty())))
@@ -102,11 +131,14 @@ fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
102131
def_id.as_local().map(|did| tcx.local_def_id_to_hir_id(did)).unwrap_or(CRATE_HIR_ID),
103132
)
104133
};
134+
do_check_unsized_params(tcx, abi, /*is_call*/ false, loc);
105135
do_check_simd_vector_abi(tcx, abi, instance.def_id(), /*is_call*/ false, loc);
106136
}
107137

108-
/// Checks that a call expression does not try to pass a vector-passed argument which requires a
109-
/// target feature that the caller does not have, as doing so causes UB because of ABI mismatch.
138+
/// Check the ABI at a call site, emitting an error when:
139+
///
140+
/// - a non-rustic ABI uses unsized parameters
141+
/// - the signature requires target features that are not enabled
110142
fn check_call_site_abi<'tcx>(
111143
tcx: TyCtxt<'tcx>,
112144
callee: Ty<'tcx>,
@@ -140,6 +172,7 @@ fn check_call_site_abi<'tcx>(
140172
// ABI failed to compute; this will not get through codegen.
141173
return;
142174
};
175+
do_check_unsized_params(tcx, callee_abi, /*is_call*/ true, loc);
143176
do_check_simd_vector_abi(tcx, callee_abi, caller.def_id(), /*is_call*/ true, loc);
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}
145178

‎tests/ui/abi/non-rustic-unsized.rs‎

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@@ -0,0 +1,66 @@
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//@ add-core-stubs
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//@ build-fail
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#![no_core]
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#![crate_type = "lib"]
5+
#![feature(no_core, unsized_fn_params)]
6+
#![allow(improper_ctypes_definitions, improper_ctypes)]
7+
8+
extern crate minicore;
9+
use minicore::*;
10+
11+
fn rust(_: [u8]) {}
12+
extern "C" fn c(_: [u8]) {}
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//~^ ERROR this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
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extern "system" fn system(_: [u8]) {}
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//~^ ERROR this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
16+
17+
#[repr(C)]
18+
struct CustomUnsized {
19+
a: i64,
20+
b: [u8],
21+
}
22+
23+
extern "C" fn c_custom_unsized(x: CustomUnsized) {}
24+
//~^ ERROR this function definition uses unsized type `CustomUnsized` which is not supported with the chosen ABI
25+
26+
#[unsafe(no_mangle)]
27+
fn entry(x: [u8], y: [u8], z: [u8], w: CustomUnsized) {
28+
rust(x);
29+
c(y);
30+
//~^ ERROR this function call uses unsized type `[u8]` which is not supported with the chosen ABI
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system(z);
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//~^ ERROR this function call uses unsized type `[u8]` which is not supported with the chosen ABI
33+
c_custom_unsized(w);
34+
//~^ ERROR this function call uses unsized type `CustomUnsized` which is not supported with the chosen ABI
35+
}
36+
37+
#[unsafe(no_mangle)]
38+
fn test_fn_ptr(rust: extern "Rust" fn(_: [u8]), c: extern "C" fn(_: [u8]), x: [u8], y: [u8]) {
39+
rust(x);
40+
c(y);
41+
//~^ ERROR this function call uses unsized type `[u8]` which is not supported with the chosen ABI
42+
}
43+
44+
#[unsafe(no_mangle)]
45+
fn test_extern(x: [u8], y: [u8]) {
46+
unsafe extern "Rust" {
47+
safe fn rust(_: [u8]);
48+
}
49+
50+
unsafe extern "system" {
51+
safe fn system(_: [u8]);
52+
}
53+
54+
rust(x);
55+
system(y);
56+
//~^ ERROR this function call uses unsized type `[u8]` which is not supported with the chosen ABI
57+
}
58+
59+
extern "C" fn c_polymorphic<T: ?Sized>(_: T) {}
60+
//~^ ERROR this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
61+
62+
#[unsafe(no_mangle)]
63+
fn test_polymorphic(x: [u8]) {
64+
c_polymorphic(x);
65+
//~^ ERROR this function call uses unsized type `[u8]` which is not supported with the chosen ABI
66+
}

‎tests/ui/abi/non-rustic-unsized.stderr‎

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@@ -0,0 +1,88 @@
1+
error: this function call uses unsized type `[u8]` which is not supported with the chosen ABI
2+
--> $DIR/non-rustic-unsized.rs:29:5
3+
|
4+
LL | c(y);
5+
| ^^^^ function called here
6+
|
7+
= help: only rustic ABIs support unsized parameters
8+
9+
error: this function call uses unsized type `[u8]` which is not supported with the chosen ABI
10+
--> $DIR/non-rustic-unsized.rs:31:5
11+
|
12+
LL | system(z);
13+
| ^^^^^^^^^ function called here
14+
|
15+
= help: only rustic ABIs support unsized parameters
16+
17+
error: this function call uses unsized type `CustomUnsized` which is not supported with the chosen ABI
18+
--> $DIR/non-rustic-unsized.rs:33:5
19+
|
20+
LL | c_custom_unsized(w);
21+
| ^^^^^^^^^^^^^^^^^^^ function called here
22+
|
23+
= help: only rustic ABIs support unsized parameters
24+
25+
error: this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
26+
--> $DIR/non-rustic-unsized.rs:12:1
27+
|
28+
LL | extern "C" fn c(_: [u8]) {}
29+
| ^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
30+
|
31+
= help: only rustic ABIs support unsized parameters
32+
33+
error: this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
34+
--> $DIR/non-rustic-unsized.rs:14:1
35+
|
36+
LL | extern "system" fn system(_: [u8]) {}
37+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
38+
|
39+
= help: only rustic ABIs support unsized parameters
40+
41+
error: this function definition uses unsized type `CustomUnsized` which is not supported with the chosen ABI
42+
--> $DIR/non-rustic-unsized.rs:23:1
43+
|
44+
LL | extern "C" fn c_custom_unsized(x: CustomUnsized) {}
45+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
46+
|
47+
= help: only rustic ABIs support unsized parameters
48+
49+
error: this function call uses unsized type `[u8]` which is not supported with the chosen ABI
50+
--> $DIR/non-rustic-unsized.rs:40:5
51+
|
52+
LL | c(y);
53+
| ^^^^ function called here
54+
|
55+
= help: only rustic ABIs support unsized parameters
56+
57+
error: this function call uses unsized type `[u8]` which is not supported with the chosen ABI
58+
--> $DIR/non-rustic-unsized.rs:55:5
59+
|
60+
LL | system(y);
61+
| ^^^^^^^^^ function called here
62+
|
63+
= help: only rustic ABIs support unsized parameters
64+
65+
error: this function call uses unsized type `[u8]` which is not supported with the chosen ABI
66+
--> $DIR/non-rustic-unsized.rs:64:5
67+
|
68+
LL | c_polymorphic(x);
69+
| ^^^^^^^^^^^^^^^^ function called here
70+
|
71+
= help: only rustic ABIs support unsized parameters
72+
73+
error: this function definition uses unsized type `[u8]` which is not supported with the chosen ABI
74+
--> $DIR/non-rustic-unsized.rs:59:1
75+
|
76+
LL | extern "C" fn c_polymorphic<T: ?Sized>(_: T) {}
77+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
78+
|
79+
= help: only rustic ABIs support unsized parameters
80+
81+
note: the above error was encountered while instantiating `fn c_polymorphic::<[u8]>`
82+
--> $DIR/non-rustic-unsized.rs:64:5
83+
|
84+
LL | c_polymorphic(x);
85+
| ^^^^^^^^^^^^^^^^
86+
87+
error: aborting due to 10 previous errors
88+

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