Rollup merge of rust-lang#35541 - hank-der-hafenarbeiter:E0045, r=jonathandturner

Updated E0045 to new error format (no bonus)

Part of rust-lang#35501
r? @jonathandturner

Author: steveklabnik

src/librustc_typeck/lib.rs

@@ -178,8 +178,10 @@ fn require_c_abi_if_variadic(tcx: TyCtxt,
                              abi: Abi,
                              span: Span) {
     if decl.variadic && abi != Abi::C {
-        span_err!(tcx.sess, span, E0045,
+        let mut err = struct_span_err!(tcx.sess, span, E0045,
                   "variadic function must have C calling convention");
+        err.span_label(span, &("variadics require C calling conventions").to_string())
+            .emit();
     }
 }
 

src/test/compile-fail/E0045.rs

@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern "Rust" { fn foo(x: u8, ...); } //~ ERROR E0045
+extern "Rust" { fn foo(x: u8, ...); }   //~ ERROR E0045
+                                        //~| NOTE variadics require C calling conventions
 
 fn main() {
 }