Unnamed repository; edit this file 'description' to name the repository.
Don't count C-variadic `...` as a parameter for fn pointers
When lowering a C-variadic function-pointer type such as
`unsafe extern "C" fn(u8, ...) -> i32`, the `...` slot was being
included in the lowered parameter list as a real input. The arity
check then required the variadic slot to be supplied, producing a
spurious E0107 ("wrong number of arguments") at the call site even
though rustc accepts the code.
The function-declaration lowering path already filters the variadic
param out; this applies the same filtering to the fn-pointer path.
Fixes rust-lang/rust-analyzer#22573
| -rw-r--r-- | crates/hir-def/src/expr_store/lower.rs | 1 | ||||
| -rw-r--r-- | crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs | 24 |
2 files changed, 25 insertions, 0 deletions
diff --git a/crates/hir-def/src/expr_store/lower.rs b/crates/hir-def/src/expr_store/lower.rs index 3094e08a53..bbc3f5333a 100644 --- a/crates/hir-def/src/expr_store/lower.rs +++ b/crates/hir-def/src/expr_store/lower.rs @@ -671,6 +671,7 @@ impl<'db> ExprCollector<'db> { } pl.params() + .filter(|it| it.dotdotdot_token().is_none()) .map(|it| { let type_ref = self.lower_type_ref_opt(it.ty(), impl_trait_lower_fn); let name = match it.pat() { diff --git a/crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs b/crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs index f6293e35d0..d1c3d1c5df 100644 --- a/crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs +++ b/crates/ide-diagnostics/src/handlers/mismatched_arg_count.rs @@ -355,6 +355,30 @@ fn f() { } #[test] + fn varargs_fn_pointer() { + check_diagnostics( + r#" +struct Funcs { + f: unsafe extern "C" fn(u8, u8, ...) -> i32, + g: unsafe extern "C" fn(...) -> i32, +} + +fn f(funcs: Funcs) { + unsafe { + (funcs.f)(0, 1); + (funcs.f)(0, 1, 2); + (funcs.f)(0); + //^ error: expected 2 arguments, found 1 + (funcs.g)(); + (funcs.g)(0); + (funcs.g)(0, 1); + } +} + "#, + ) + } + + #[test] fn arg_count_lambda() { check_diagnostics( r#" |