Update link_ordinal duplicate attribute handling.

This removes the duplicate check, as this is now handled in a
centralized location.

Author: ehuss

compiler/rustc_typeck/src/collect.rs

@@ -2865,14 +2865,6 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
         } else if attr.has_name(sym::link_name) {
             codegen_fn_attrs.link_name = attr.value_str();
         } else if attr.has_name(sym::link_ordinal) {
-            if link_ordinal_span.is_some() {
-                tcx.sess
-                    .struct_span_err(
-                        attr.span,
-                        "multiple `link_ordinal` attributes on a single definition",
-                    )
-                    .emit();
-            }
             link_ordinal_span = Some(attr.span);
             if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
                 codegen_fn_attrs.link_ordinal = ordinal;

src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.rs

@@ -4,9 +4,8 @@
 
 #[link(name = "foo", kind = "raw-dylib")]
 extern "C" {
-    #[link_ordinal(1)]
+    #[link_ordinal(1)] //~ ERROR multiple `link_ordinal` attributes
     #[link_ordinal(2)]
-    //~^ ERROR multiple `link_ordinal` attributes on a single definition
     fn foo();
 }
 

src/test/ui/rfc-2627-raw-dylib/link-ordinal-multiple.stderr

@@ -7,7 +7,13 @@ LL | #![feature(raw_dylib)]
    = note: `#[warn(incomplete_features)]` on by default
    = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
 
-error: multiple `link_ordinal` attributes on a single definition
+error: multiple `link_ordinal` attributes
+  --> $DIR/link-ordinal-multiple.rs:7:5
+   |
+LL |     #[link_ordinal(1)]
+   |     ^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+note: attribute also specified here
   --> $DIR/link-ordinal-multiple.rs:8:5
    |
 LL |     #[link_ordinal(2)]