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c-variadic: reject functions with unsupported extern ABI

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Folkert de Vries 2025-09-08 19:27:07 +02:00
parent 0c96200f26
commit 9196844f0d
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GPG key ID: 1F17F6FFD112B97C
9 changed files with 88 additions and 49 deletions
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5
compiler/rustc_ast/src/ast.rs
View file

@ -2325,6 +2325,11 @@ impl FnSig {
}
}
}
/// The span of the header's extern, or where to insert it if empty.
pub fn extern_span(&self) -> Span {
self.header.ext.span().unwrap_or(self.safety_span().shrink_to_hi())
}
}
/// A constraint on an associated item.

7
compiler/rustc_ast_passes/messages.ftl
View file

@ -57,8 +57,6 @@ ast_passes_auto_super_lifetime = auto traits cannot have super traits or lifetim
.label = {ast_passes_auto_super_lifetime}
.suggestion = remove the super traits or lifetime bounds
ast_passes_bad_c_variadic = defining functions with C-variadic arguments is only allowed for free functions with the "C" or "C-unwind" calling convention
ast_passes_body_in_extern = incorrect `{$kind}` inside `extern` block
.cannot_have = cannot have a body
.invalid = the invalid body
@ -68,11 +66,16 @@ ast_passes_bound_in_context = bounds on `type`s in {$ctx} have no effect
ast_passes_c_variadic_associated_function = associated functions cannot have a C variable argument list
ast_passes_c_variadic_bad_extern = `...` is not supported for `extern "{$abi}"` functions
.label = `extern "{$abi}"` because of this
.help = only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
ast_passes_c_variadic_must_be_unsafe =
functions with a C variable argument list must be unsafe
.suggestion = add the `unsafe` keyword to this definition
ast_passes_c_variadic_no_extern = `...` is not supported for non-extern functions
.help = only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
ast_passes_const_and_c_variadic = functions cannot be both `const` and C-variadic
.const = `const` because of this

7
compiler/rustc_ast_passes/src/ast_validation.rs
View file

@ -698,7 +698,6 @@ impl<'a> AstValidator<'a> {
FnCtxt::Foreign => return,
FnCtxt::Free => match sig.header.ext {
Extern::Implicit(_) => {
// Implicitly defaults to C.
if !matches!(sig.header.safety, Safety::Unsafe(_)) {
self.dcx().emit_err(errors::CVariadicMustBeUnsafe {
span: variadic_param.span,
@ -708,7 +707,11 @@ impl<'a> AstValidator<'a> {
}
Extern::Explicit(StrLit { symbol_unescaped, .. }, _) => {
if !matches!(symbol_unescaped, sym::C | sym::C_dash_unwind) {
self.dcx().emit_err(errors::BadCVariadic { span: variadic_param.span });
self.dcx().emit_err(errors::CVariadicBadExtern {
span: variadic_param.span,
abi: symbol_unescaped,
extern_span: sig.extern_span(),
});
}
if !matches!(sig.header.safety, Safety::Unsafe(_)) {

9
compiler/rustc_ast_passes/src/errors.rs
View file

@ -327,6 +327,7 @@ pub(crate) struct CVariadicAssociatedFunction {
#[derive(Diagnostic)]
#[diag(ast_passes_c_variadic_no_extern)]
#[help]
pub(crate) struct CVariadicNoExtern {
#[primary_span]
pub span: Span,
@ -348,10 +349,14 @@ pub(crate) struct CVariadicMustBeUnsafe {
}
#[derive(Diagnostic)]
#[diag(ast_passes_bad_c_variadic)]
pub(crate) struct BadCVariadic {
#[diag(ast_passes_c_variadic_bad_extern)]
#[help]
pub(crate) struct CVariadicBadExtern {
#[primary_span]
pub span: Span,
pub abi: Symbol,
#[label]
pub extern_span: Span,
}
#[derive(Diagnostic)]

2
tests/ui/c-variadic/issue-86053-1.stderr
View file

@ -51,6 +51,8 @@ error: `...` is not supported for non-extern functions
|
LL | self , ... , self , self , ... ) where F : FnOnce ( & 'a & 'b usize ) {
| ^^^
|
= help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
error[E0412]: cannot find type `F` in this scope
--> $DIR/issue-86053-1.rs:11:48

2
tests/ui/cmse-nonsecure/cmse-nonsecure-entry/generics.rs
View file

@ -67,6 +67,6 @@ extern "cmse-nonsecure-entry" fn wrapped_trait_object(x: WrapperTransparent) ->
}
unsafe extern "cmse-nonsecure-entry" fn c_variadic(_: u32, _: ...) {
//~^ ERROR defining functions with C-variadic arguments is only allowed for free functions with the "C" or "C-unwind" calling convention
//~^ ERROR `...` is not supported for `extern "cmse-nonsecure-entry"` functions
//~| ERROR requires `va_list` lang_item
}

8
tests/ui/cmse-nonsecure/cmse-nonsecure-entry/generics.stderr
View file

@ -1,8 +1,12 @@
error: defining functions with C-variadic arguments is only allowed for free functions with the "C" or "C-unwind" calling convention
error: `...` is not supported for `extern "cmse-nonsecure-entry"` functions
--> $DIR/generics.rs:69:60
|
LL | unsafe extern "cmse-nonsecure-entry" fn c_variadic(_: u32, _: ...) {
| ^^^^^^
| ----------------------------- ^^^^^^
| |
| `extern "cmse-nonsecure-entry"` because of this
|
= help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
error[E0798]: functions with the `"cmse-nonsecure-entry"` ABI cannot contain generics in their type
--> $DIR/generics.rs:30:1

3
tests/ui/parser/variadic-ffi-semantic-restrictions.rs
View file

@ -9,6 +9,9 @@ fn f1_1(x: isize, ...) {}
fn f1_2(...) {}
//~^ ERROR `...` is not supported for non-extern functions
unsafe extern "Rust" fn f1_3(...) {}
//~^ ERROR `...` is not supported for `extern "Rust"` functions
extern "C" fn f2_1(x: isize, ...) {}
//~^ ERROR functions with a C variable argument list must be unsafe

94
tests/ui/parser/variadic-ffi-semantic-restrictions.stderr
View file

@ -3,15 +3,29 @@ error: `...` is not supported for non-extern functions
|
LL | fn f1_1(x: isize, ...) {}
| ^^^
|
= help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
error: `...` is not supported for non-extern functions
--> $DIR/variadic-ffi-semantic-restrictions.rs:9:9
|
LL | fn f1_2(...) {}
| ^^^
|
= help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
error: `...` is not supported for `extern "Rust"` functions
--> $DIR/variadic-ffi-semantic-restrictions.rs:12:30
|
LL | unsafe extern "Rust" fn f1_3(...) {}
| ------------- ^^^
| |
| `extern "Rust"` because of this
|
= help: only `extern "C"` and `extern "C-unwind"` functions may have a C variable argument list
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:12:30
--> $DIR/variadic-ffi-semantic-restrictions.rs:15:30
|
LL | extern "C" fn f2_1(x: isize, ...) {}
| ^^^
@ -22,7 +36,7 @@ LL | unsafe extern "C" fn f2_1(x: isize, ...) {}
| ++++++
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:15:20
--> $DIR/variadic-ffi-semantic-restrictions.rs:18:20
|
LL | extern "C" fn f2_2(...) {}
| ^^^
@ -33,13 +47,13 @@ LL | unsafe extern "C" fn f2_2(...) {}
| ++++++
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:18:20
--> $DIR/variadic-ffi-semantic-restrictions.rs:21:20
|
LL | extern "C" fn f2_3(..., x: isize) {}
| ^^^
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:21:30
--> $DIR/variadic-ffi-semantic-restrictions.rs:24:30
|
LL | extern "C" fn f3_1(x: isize, ...) {}
| ^^^
@ -50,7 +64,7 @@ LL | unsafe extern "C" fn f3_1(x: isize, ...) {}
| ++++++
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:24:20
--> $DIR/variadic-ffi-semantic-restrictions.rs:27:20
|
LL | extern "C" fn f3_2(...) {}
| ^^^
@ -61,25 +75,25 @@ LL | unsafe extern "C" fn f3_2(...) {}
| ++++++
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:27:20
--> $DIR/variadic-ffi-semantic-restrictions.rs:30:20
|
LL | extern "C" fn f3_3(..., x: isize) {}
| ^^^
error: functions cannot be both `const` and C-variadic
--> $DIR/variadic-ffi-semantic-restrictions.rs:30:1
--> $DIR/variadic-ffi-semantic-restrictions.rs:33:1
|
LL | const unsafe extern "C" fn f4_1(x: isize, ...) {}
| ^^^^^ `const` because of this ^^^ C-variadic because of this
error: functions cannot be both `const` and C-variadic
--> $DIR/variadic-ffi-semantic-restrictions.rs:34:1
--> $DIR/variadic-ffi-semantic-restrictions.rs:37:1
|
LL | const extern "C" fn f4_2(x: isize, ...) {}
| ^^^^^ `const` because of this ^^^ C-variadic because of this
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:34:36
--> $DIR/variadic-ffi-semantic-restrictions.rs:37:36
|
LL | const extern "C" fn f4_2(x: isize, ...) {}
| ^^^
@ -90,19 +104,19 @@ LL | const unsafe extern "C" fn f4_2(x: isize, ...) {}
| ++++++
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:39:26
--> $DIR/variadic-ffi-semantic-restrictions.rs:42:26
|
LL | const extern "C" fn f4_3(..., x: isize, ...) {}
| ^^^
error: functions cannot be both `const` and C-variadic
--> $DIR/variadic-ffi-semantic-restrictions.rs:39:1
--> $DIR/variadic-ffi-semantic-restrictions.rs:42:1
|
LL | const extern "C" fn f4_3(..., x: isize, ...) {}
| ^^^^^ `const` because of this ^^^ C-variadic because of this
error: functions with a C variable argument list must be unsafe
--> $DIR/variadic-ffi-semantic-restrictions.rs:39:41
--> $DIR/variadic-ffi-semantic-restrictions.rs:42:41
|
LL | const extern "C" fn f4_3(..., x: isize, ...) {}
| ^^^
@ -113,49 +127,49 @@ LL | const unsafe extern "C" fn f4_3(..., x: isize, ...) {}
| ++++++
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:45:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:48:13
|
LL | fn e_f2(..., x: isize);
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:52:23
--> $DIR/variadic-ffi-semantic-restrictions.rs:55:23
|
LL | fn i_f1(x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:54:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:57:13
|
LL | fn i_f2(...) {}
| ^^^
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:56:13
|
LL | fn i_f3(..., x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:56:28
|
LL | fn i_f3(..., x: isize, ...) {}
| ^^^
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:59:13
|
LL | fn i_f4(..., x: isize, ...) {}
LL | fn i_f3(..., x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:59:28
|
LL | fn i_f3(..., x: isize, ...) {}
| ^^^
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:62:13
|
LL | fn i_f4(..., x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:62:28
|
LL | fn i_f4(..., x: isize, ...) {}
| ^^^
error: functions cannot be both `const` and C-variadic
--> $DIR/variadic-ffi-semantic-restrictions.rs:62:5
--> $DIR/variadic-ffi-semantic-restrictions.rs:65:5
|
LL | const fn i_f5(x: isize, ...) {}
| ^^^^^ ^^^ C-variadic because of this
@ -163,49 +177,49 @@ LL | const fn i_f5(x: isize, ...) {}
| `const` because of this
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:62:29
--> $DIR/variadic-ffi-semantic-restrictions.rs:65:29
|
LL | const fn i_f5(x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:69:23
--> $DIR/variadic-ffi-semantic-restrictions.rs:72:23
|
LL | fn t_f1(x: isize, ...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:71:23
--> $DIR/variadic-ffi-semantic-restrictions.rs:74:23
|
LL | fn t_f2(x: isize, ...);
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:73:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:76:13
|
LL | fn t_f3(...) {}
| ^^^
error: associated functions cannot have a C variable argument list
--> $DIR/variadic-ffi-semantic-restrictions.rs:75:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:78:13
|
LL | fn t_f4(...);
| ^^^
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:77:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:80:13
|
LL | fn t_f5(..., x: isize) {}
| ^^^
error: `...` must be the last argument of a C-variadic function
--> $DIR/variadic-ffi-semantic-restrictions.rs:79:13
--> $DIR/variadic-ffi-semantic-restrictions.rs:82:13
|
LL | fn t_f6(..., x: isize);
| ^^^
error[E0493]: destructor of `VaListImpl<'_>` cannot be evaluated at compile-time
--> $DIR/variadic-ffi-semantic-restrictions.rs:30:43
--> $DIR/variadic-ffi-semantic-restrictions.rs:33:43
|
LL | const unsafe extern "C" fn f4_1(x: isize, ...) {}
| ^^^ - value is dropped here
@ -213,7 +227,7 @@ LL | const unsafe extern "C" fn f4_1(x: isize, ...) {}
| the destructor for this type cannot be evaluated in constant functions
error[E0493]: destructor of `VaListImpl<'_>` cannot be evaluated at compile-time
--> $DIR/variadic-ffi-semantic-restrictions.rs:34:36
--> $DIR/variadic-ffi-semantic-restrictions.rs:37:36
|
LL | const extern "C" fn f4_2(x: isize, ...) {}
| ^^^ - value is dropped here
@ -221,13 +235,13 @@ LL | const extern "C" fn f4_2(x: isize, ...) {}
| the destructor for this type cannot be evaluated in constant functions
error[E0493]: destructor of `VaListImpl<'_>` cannot be evaluated at compile-time
--> $DIR/variadic-ffi-semantic-restrictions.rs:62:29
--> $DIR/variadic-ffi-semantic-restrictions.rs:65:29
|
LL | const fn i_f5(x: isize, ...) {}
| ^^^ - value is dropped here
| |
| the destructor for this type cannot be evaluated in constant functions
error: aborting due to 32 previous errors
error: aborting due to 33 previous errors
For more information about this error, try `rustc --explain E0493`.