Rollup merge of #117370 - nicholasbishop:bishop-better-c-variadic-errors, r=oli-obk
C-variadic error improvements A couple improvements for c-variadic errors: 1. Fix the bad-c-variadic error being emitted multiple times. If a function incorrectly contains multiple `...` args, and is also not foreign or `unsafe extern "C"`, only emit the latter error once rather than once per `...`. 2. Explicitly reject `const` C-variadic functions. Trying to use C-variadics in a const function would previously fail with an error like "destructor of `VaListImpl<'_>` cannot be evaluated at compile-time". Add an explicit check for const C-variadics to provide a clearer error: "functions cannot be both `const` and C-variadic". This also addresses one of the concerns in https://github.com/rust-lang/rust/issues/44930: "Ensure that even when this gets stabilized for regular functions, it is still rejected on const fn."
This commit is contained in:
Guillaume Gomez
GitHub
commit
784f04b367
6 changed files with 136 additions and 50 deletions
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@ -42,6 +42,10 @@ ast_passes_const_and_async = functions cannot be both `const` and `async`
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.async = `async` because of this
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.label = {""}
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ast_passes_const_and_c_variadic = functions cannot be both `const` and C-variadic
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.const = `const` because of this
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.variadic = C-variadic because of this
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ast_passes_const_without_body =
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free constant item without body
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.suggestion = provide a definition for the constant
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@ -482,9 +482,36 @@ impl<'a> AstValidator<'a> {
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}
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}
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/// Reject C-variadic type unless the function is foreign,
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/// or free and `unsafe extern "C"` semantically.
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/// Reject invalid C-variadic types.
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///
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/// C-variadics must be:
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/// - Non-const
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/// - Either foreign, or free and `unsafe extern "C"` semantically
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fn check_c_variadic_type(&self, fk: FnKind<'a>) {
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let variadic_spans: Vec<_> = fk
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.decl()
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.inputs
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.iter()
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.filter(|arg| matches!(arg.ty.kind, TyKind::CVarArgs))
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.map(|arg| arg.span)
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.collect();
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if variadic_spans.is_empty() {
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return;
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}
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if let Some(header) = fk.header() {
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if let Const::Yes(const_span) = header.constness {
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let mut spans = variadic_spans.clone();
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spans.push(const_span);
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self.err_handler().emit_err(errors::ConstAndCVariadic {
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spans,
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const_span,
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variadic_spans: variadic_spans.clone(),
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});
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}
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}
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match (fk.ctxt(), fk.header()) {
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(Some(FnCtxt::Foreign), _) => return,
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(Some(FnCtxt::Free), Some(header)) => match header.ext {
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@ -499,11 +526,7 @@ impl<'a> AstValidator<'a> {
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_ => {}
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};
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for Param { ty, span, .. } in &fk.decl().inputs {
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if let TyKind::CVarArgs = ty.kind {
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self.err_handler().emit_err(errors::BadCVariadic { span: *span });
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}
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}
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self.err_handler().emit_err(errors::BadCVariadic { span: variadic_spans });
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}
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fn check_item_named(&self, ident: Ident, kind: &str) {
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@ -271,7 +271,7 @@ pub struct ExternItemAscii {
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#[diag(ast_passes_bad_c_variadic)]
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pub struct BadCVariadic {
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#[primary_span]
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pub span: Span,
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pub span: Vec<Span>,
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}
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#[derive(Diagnostic)]
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@ -583,6 +583,17 @@ pub struct ConstAndAsync {
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pub span: Span,
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}
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#[derive(Diagnostic)]
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#[diag(ast_passes_const_and_c_variadic)]
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pub struct ConstAndCVariadic {
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#[primary_span]
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pub spans: Vec<Span>,
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#[label(ast_passes_const)]
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pub const_span: Span,
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#[label(ast_passes_variadic)]
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pub variadic_spans: Vec<Span>,
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}
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#[derive(Diagnostic)]
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#[diag(ast_passes_pattern_in_foreign, code = "E0130")]
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pub struct PatternInForeign {
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@ -50,13 +50,7 @@ error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/issue-86053-1.rs:11:12
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LL | self , ... , self , self , ... ) where F : FnOnce ( & 'a & 'b usize ) {
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/issue-86053-1.rs:11:36
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LL | self , ... , self , self , ... ) where F : FnOnce ( & 'a & 'b usize ) {
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| ^^^
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| ^^^ ^^^
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error[E0412]: cannot find type `F` in this scope
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--> $DIR/issue-86053-1.rs:11:48
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@ -76,6 +70,6 @@ help: you might be missing a type parameter
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LL | fn ordering4 < 'a , 'b, F > ( a : , self , self , self ,
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| +++
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error: aborting due to 11 previous errors
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error: aborting due to 10 previous errors
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For more information about this error, try `rustc --explain E0412`.
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@ -32,6 +32,18 @@ extern "C" fn f3_3(..., x: isize) {}
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//~^ ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR `...` must be the last argument of a C-variadic function
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const unsafe extern "C" fn f4_1(x: isize, ...) {}
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//~^ ERROR functions cannot be both `const` and C-variadic
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const extern "C" fn f4_2(x: isize, ...) {}
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//~^ ERROR functions cannot be both `const` and C-variadic
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//~| ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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const extern "C" fn f4_3(..., x: isize, ...) {}
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//~^ ERROR functions cannot be both `const` and C-variadic
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//~| ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR `...` must be the last argument of a C-variadic function
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extern "C" {
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fn e_f1(...);
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//~^ ERROR C-variadic function must be declared with at least one named argument
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@ -49,12 +61,13 @@ impl X {
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//~| ERROR C-variadic function must be declared with at least one named argument
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fn i_f3(..., x: isize, ...) {}
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//~^ ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR `...` must be the last argument of a C-variadic function
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fn i_f4(..., x: isize, ...) {}
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//~^ ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR `...` must be the last argument of a C-variadic function
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const fn i_f5(x: isize, ...) {}
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//~^ ERROR only foreign or `unsafe extern "C"` functions may be C-variadic
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//~| ERROR functions cannot be both `const` and C-variadic
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}
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trait T {
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@ -76,131 +76,172 @@ error: only foreign or `unsafe extern "C"` functions may be C-variadic
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LL | extern "C" fn f3_3(..., x: isize) {}
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| ^^^
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error: functions cannot be both `const` and C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:35:1
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LL | const unsafe extern "C" fn f4_1(x: isize, ...) {}
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| ^^^^^ `const` because of this ^^^ C-variadic because of this
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error: functions cannot be both `const` and C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:38:1
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LL | const extern "C" fn f4_2(x: isize, ...) {}
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| ^^^^^ `const` because of this ^^^ C-variadic because of this
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:38:36
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LL | const extern "C" fn f4_2(x: isize, ...) {}
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| ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:42:26
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LL | const extern "C" fn f4_3(..., x: isize, ...) {}
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| ^^^
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error: functions cannot be both `const` and C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:42:1
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LL | const extern "C" fn f4_3(..., x: isize, ...) {}
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| ^^^^^ ^^^ ^^^ C-variadic because of this
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| | |
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| | C-variadic because of this
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| `const` because of this
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:42:26
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LL | const extern "C" fn f4_3(..., x: isize, ...) {}
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| ^^^ ^^^
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error: C-variadic function must be declared with at least one named argument
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--> $DIR/variadic-ffi-semantic-restrictions.rs:36:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:48:13
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LL | fn e_f1(...);
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| ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:38:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:50:13
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LL | fn e_f2(..., x: isize);
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:45:23
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--> $DIR/variadic-ffi-semantic-restrictions.rs:57:23
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LL | fn i_f1(x: isize, ...) {}
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| ^^^
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error: C-variadic function must be declared with at least one named argument
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--> $DIR/variadic-ffi-semantic-restrictions.rs:47:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:59:13
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LL | fn i_f2(...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:47:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:59:13
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LL | fn i_f2(...) {}
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| ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:50:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:62:13
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LL | fn i_f3(..., x: isize, ...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:50:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:62:13
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LL | fn i_f3(..., x: isize, ...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:50:28
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LL | fn i_f3(..., x: isize, ...) {}
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| ^^^
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| ^^^ ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:54:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:65:13
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LL | fn i_f4(..., x: isize, ...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:54:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:65:13
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LL | fn i_f4(..., x: isize, ...) {}
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| ^^^
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| ^^^ ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:54:28
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error: functions cannot be both `const` and C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:68:5
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LL | fn i_f4(..., x: isize, ...) {}
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| ^^^
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LL | const fn i_f5(x: isize, ...) {}
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| ^^^^^ ^^^ C-variadic because of this
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| |
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| `const` because of this
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:61:23
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--> $DIR/variadic-ffi-semantic-restrictions.rs:68:29
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LL | const fn i_f5(x: isize, ...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:74:23
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LL | fn t_f1(x: isize, ...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:63:23
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--> $DIR/variadic-ffi-semantic-restrictions.rs:76:23
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LL | fn t_f2(x: isize, ...);
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| ^^^
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error: C-variadic function must be declared with at least one named argument
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--> $DIR/variadic-ffi-semantic-restrictions.rs:65:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:78:13
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LL | fn t_f3(...) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:65:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:78:13
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LL | fn t_f3(...) {}
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| ^^^
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error: C-variadic function must be declared with at least one named argument
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--> $DIR/variadic-ffi-semantic-restrictions.rs:68:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:81:13
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LL | fn t_f4(...);
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:68:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:81:13
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|
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LL | fn t_f4(...);
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| ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:71:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:84:13
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|
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LL | fn t_f5(..., x: isize) {}
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:71:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:84:13
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|
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LL | fn t_f5(..., x: isize) {}
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| ^^^
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error: `...` must be the last argument of a C-variadic function
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--> $DIR/variadic-ffi-semantic-restrictions.rs:74:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:87:13
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|
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LL | fn t_f6(..., x: isize);
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| ^^^
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error: only foreign or `unsafe extern "C"` functions may be C-variadic
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--> $DIR/variadic-ffi-semantic-restrictions.rs:74:13
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--> $DIR/variadic-ffi-semantic-restrictions.rs:87:13
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|
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LL | fn t_f6(..., x: isize);
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| ^^^
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error: aborting due to 34 previous errors
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error: aborting due to 40 previous errors
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