[E0045] Variadic Parameters Used on Non-C ABI Function

[MahadMuhammad]

Variadic Parameters Used on Non-C ABI Function - E0045

• Added error code support for using variadic parameters used on Non-C ABI function.
• Fixes Error Variadic Parameters - [E0045] #2382

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Code tested from E0045

// https://doc.rust-lang.org/error_codes/E0045.html
#![allow(unused)]
fn main() {
    extern "Rust" {
        fn foo(x: u8, ...); // { dg-error "C-variadic function must have C or cdecl calling convention" }
    }
}

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Output:

➜  gccrs-build gcc/crab1 /home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/abi-vardaic.rs                           
/home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/abi-vardaic.rs:5:9: error: C-variadic function must have C or cdecl calling convention [E0045]
    5 |         fn foo(x: u8, ...); // { dg-error "C-variadic function must have C or cdecl calling convention" }
      |         ^~

Analyzing compilation unit

Time variable                                   usr           sys          wall           GGC
 TOTAL                              :   0.00          0.00          0.00          146k
Extra diagnostic checks enabled; compiler may run slowly.
Configure with --enable-checking=release to disable checks.

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gcc/rust/ChangeLog:

* typecheck/rust-hir-type-check-implitem.cc (TypeCheckTopLevelExternItem::visit): Added check for error code support.

gcc/testsuite/ChangeLog:

* rust/compile/abi-vardaic.rs: New test.

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[CohenArthur]

LGTM!