From 57548aa096f31d90b9606f882f5815a93b2570b3 Mon Sep 17 00:00:00 2001
From: Caleb Cartwright <caleb.cartwright@outlook.com>
Date: Tue, 7 Sep 2021 19:49:56 -0500
Subject: [PATCH] fix: resolve idempotency issue in extern body elements

---
 src/missed_spans.rs        | 20 ++++++++++++--------
 tests/source/issue_4963.rs |  5 +++++
 tests/target/issue_4963.rs |  9 +++++++++
 3 files changed, 26 insertions(+), 8 deletions(-)
 create mode 100644 tests/source/issue_4963.rs
 create mode 100644 tests/target/issue_4963.rs

diff --git a/src/missed_spans.rs b/src/missed_spans.rs
index 263d840785a..28edcb784b4 100644
--- a/src/missed_spans.rs
+++ b/src/missed_spans.rs
@@ -51,6 +51,14 @@ impl<'a> FmtVisitor<'a> {
     }
 
     pub(crate) fn format_missing_with_indent(&mut self, end: BytePos) {
+        self.format_missing_indent(end, true)
+    }
+
+    pub(crate) fn format_missing_no_indent(&mut self, end: BytePos) {
+        self.format_missing_indent(end, false)
+    }
+
+    fn format_missing_indent(&mut self, end: BytePos, should_indent: bool) {
         let config = self.config;
         self.format_missing_inner(end, |this, last_snippet, snippet| {
             this.push_str(last_snippet.trim_end());
@@ -58,14 +66,10 @@ impl<'a> FmtVisitor<'a> {
                 // No new lines in the snippet.
                 this.push_str("\n");
             }
-            let indent = this.block_indent.to_string(config);
-            this.push_str(&indent);
-        })
-    }
-
-    pub(crate) fn format_missing_no_indent(&mut self, end: BytePos) {
-        self.format_missing_inner(end, |this, last_snippet, _| {
-            this.push_str(last_snippet.trim_end());
+            if should_indent {
+                let indent = this.block_indent.to_string(config);
+                this.push_str(&indent);
+            }
         })
     }
 
diff --git a/tests/source/issue_4963.rs b/tests/source/issue_4963.rs
new file mode 100644
index 00000000000..32e1f6cd41b
--- /dev/null
+++ b/tests/source/issue_4963.rs
@@ -0,0 +1,5 @@
+mod test {
+    extern "C" {fn test();}
+}
+
+extern "C" {fn test();}
\ No newline at end of file
diff --git a/tests/target/issue_4963.rs b/tests/target/issue_4963.rs
new file mode 100644
index 00000000000..0c3c13579c1
--- /dev/null
+++ b/tests/target/issue_4963.rs
@@ -0,0 +1,9 @@
+mod test {
+    extern "C" {
+        fn test();
+    }
+}
+
+extern "C" {
+    fn test();
+}