Handle 'extern "Rust"' in format_abi()

src/items.rs

@@ -10,6 +10,7 @@
 
 // Formatting top-level items - functions, structs, enums, traits, impls.
 
+use std::borrow::Cow;
 use std::cmp::min;
 
 use syntax::{abi, ast, ptr, symbol};
@@ -126,7 +127,7 @@ impl Rewrite for ast::Local {
 #[allow(dead_code)]
 struct Item<'a> {
     keyword: &'static str,
-    abi: String,
+    abi: Cow<'static, str>,
     vis: Option<&'a ast::Visibility>,
     body: Vec<BodyElement<'a>>,
     span: Span,
@@ -134,14 +135,9 @@ struct Item<'a> {
 
 impl<'a> Item<'a> {
     fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
-        let abi = if fm.abi == abi::Abi::C && !config.force_explicit_abi() {
-            "extern".into()
-        } else {
-            format!("extern {}", fm.abi)
-        };
         Item {
             keyword: "",
-            abi: abi,
+            abi: format_abi(fm.abi, config.force_explicit_abi(), true),
             vis: None,
             body: fm.items
                 .iter()

src/types.rs

@@ -11,7 +11,6 @@
 use std::iter::ExactSizeIterator;
 use std::ops::Deref;
 
-use syntax::abi;
 use syntax::ast::{self, FunctionRetTy, Mutability};
 use syntax::codemap::{self, BytePos, Span};
 use syntax::print::pprust;
@@ -26,7 +25,7 @@ use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListTac
             SeparatorPlace, SeparatorTactic};
 use rewrite::{Rewrite, RewriteContext};
 use shape::Shape;
-use utils::{colon_spaces, extra_offset, format_mutability, last_line_width, mk_sp};
+use utils::{colon_spaces, extra_offset, format_abi, format_mutability, last_line_width, mk_sp};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum PathContext {
@@ -792,12 +791,11 @@ fn rewrite_bare_fn(
 
     result.push_str(::utils::format_unsafety(bare_fn.unsafety));
 
-    if bare_fn.abi != abi::Abi::Rust {
-        result.push_str(&::utils::format_abi(
-            bare_fn.abi,
-            context.config.force_explicit_abi(),
-        ));
-    }
+    result.push_str(&format_abi(
+        bare_fn.abi,
+        context.config.force_explicit_abi(),
+        false,
+    ));
 
     result.push_str("fn");
 

src/utils.rs

@@ -88,8 +88,10 @@ pub fn format_mutability(mutability: ast::Mutability) -> &'static str {
 }
 
 #[inline]
-pub fn format_abi(abi: abi::Abi, explicit_abi: bool) -> Cow<'static, str> {
-    if abi == abi::Abi::C && !explicit_abi {
+pub fn format_abi(abi: abi::Abi, explicit_abi: bool, is_mod: bool) -> Cow<'static, str> {
+    if abi == abi::Abi::Rust && !is_mod {
+        Cow::from("")
+    } else if abi == abi::Abi::C && !explicit_abi {
         Cow::from("extern ")
     } else {
         Cow::from(format!("extern {} ", abi))