Improving Pair construction.

Author: adetaylor

syntax/impls.rs

@@ -300,14 +300,22 @@ impl Borrow<Type> for &Impl {
 
 impl Pair {
     /// Use this constructor when the item can't have a different
-    /// name in Rust and C++. For cases where #[rust_name] and similar
-    /// attributes can be used, construct the object by hand.
+    /// name in Rust and C++.
     pub fn new(ns: Namespace, ident: Ident) -> Self {
         Self {
             rust: ident.clone(),
             cxx: CppName::new(ns, ident),
         }
     }
+
+    /// Use this constructor when attributes such as #[rust_name]
+    /// can be used to potentially give a different name in Rust vs C++.
+    pub fn new_from_differing_names(ns: Namespace, cxx_ident: Ident, rust_ident: Ident) -> Self {
+        Self {
+            rust: rust_ident,
+            cxx: CppName::new(ns, cxx_ident),
+        }
+    }
 }
 
 impl ResolvableName {

syntax/parse.rs

@@ -3,7 +3,7 @@ use crate::syntax::file::{Item, ItemForeignMod};
 use crate::syntax::report::Errors;
 use crate::syntax::Atom::*;
 use crate::syntax::{
-    attrs, error, Api, CppName, Doc, Enum, ExternFn, ExternType, Impl, Include, IncludeKind, Lang,
+    attrs, error, Api, Doc, Enum, ExternFn, ExternType, Impl, Include, IncludeKind, Lang,
     Namespace, Pair, Receiver, Ref, ResolvableName, Signature, Slice, Struct, Ty1, Type, TypeAlias,
     Var, Variant,
 };
@@ -398,10 +398,11 @@ fn parse_extern_fn(
     let throws = throws_tokens.is_some();
     let unsafety = foreign_fn.sig.unsafety;
     let fn_token = foreign_fn.sig.fn_token;
-    let ident = Pair {
-        cxx: CppName::new(ns, cxx_name.unwrap_or(foreign_fn.sig.ident.clone())),
-        rust: rust_name.unwrap_or(foreign_fn.sig.ident.clone()),
-    };
+    let ident = Pair::new_from_differing_names(
+        ns,
+        cxx_name.unwrap_or(foreign_fn.sig.ident.clone()),
+        rust_name.unwrap_or(foreign_fn.sig.ident.clone()),
+    );
     let paren_token = foreign_fn.sig.paren_token;
     let semi_token = foreign_fn.semi_token;
     let api_function = match lang {