From 3cb7d5ab766e3858c3e01ed9e65540a44878281e Mon Sep 17 00:00:00 2001
From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Thu, 25 Feb 2021 23:20:56 +0100
Subject: [PATCH] Fix the ranges in unified diff output

---
 CHANGELOG.md                                    |  1 +
 src/snapshots/similar__udiff__unified_diff.snap |  4 ++--
 ...lar__udiff__unified_diff_newline_hint-2.snap |  2 +-
 ...milar__udiff__unified_diff_newline_hint.snap |  2 +-
 .../snapshots/similar__text__unified_diff.snap  |  2 +-
 src/udiff.rs                                    | 17 +++++++++--------
 6 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 49b35da..30bf8e9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ All notable changes to similar are documented here.
 * Added a compacting step to clean up diffs.  This results in nicer looking diffs and
   fewer edits.  This is happening automatically for captured diffs and is exposed
   through the `Capture` type.
+* Fix incorrect ranges in unified diff output.
 
 ## 1.2.2
 
diff --git a/src/snapshots/similar__udiff__unified_diff.snap b/src/snapshots/similar__udiff__unified_diff.snap
index 799b38c..5345b0b 100644
--- a/src/snapshots/similar__udiff__unified_diff.snap
+++ b/src/snapshots/similar__udiff__unified_diff.snap
@@ -4,7 +4,7 @@ expression: "&diff.unified_diff().header(\"a.txt\", \"b.txt\").to_string()"
 ---
 --- a.txt
 +++ b.txt
-@@ -15,3 +19,3 @@
+@@ -16,7 +16,7 @@
  p
  q
  r
@@ -13,7 +13,7 @@ expression: "&diff.unified_diff().header(\"a.txt\", \"b.txt\").to_string()"
  t
  u
  v
-@@ -37,3 +41,3 @@
+@@ -38,7 +38,7 @@
  L
  M
  N
diff --git a/src/snapshots/similar__udiff__unified_diff_newline_hint-2.snap b/src/snapshots/similar__udiff__unified_diff_newline_hint-2.snap
index 7e8489e..9a5d922 100644
--- a/src/snapshots/similar__udiff__unified_diff_newline_hint-2.snap
+++ b/src/snapshots/similar__udiff__unified_diff_newline_hint-2.snap
@@ -4,7 +4,7 @@ expression: "&diff.unified_diff().missing_newline_hint(false).header(\"a.txt\",\
 ---
 --- a.txt
 +++ b.txt
-@@ -0 +0 @@
+@@ -1 +1 @@
 -a
 +b
 
diff --git a/src/snapshots/similar__udiff__unified_diff_newline_hint.snap b/src/snapshots/similar__udiff__unified_diff_newline_hint.snap
index 0d3b137..d181b28 100644
--- a/src/snapshots/similar__udiff__unified_diff_newline_hint.snap
+++ b/src/snapshots/similar__udiff__unified_diff_newline_hint.snap
@@ -4,7 +4,7 @@ expression: "&diff.unified_diff().header(\"a.txt\", \"b.txt\").to_string()"
 ---
 --- a.txt
 +++ b.txt
-@@ -0 +0 @@
+@@ -1 +1 @@
 -a
 +b
 \ No newline at end of file
diff --git a/src/text/snapshots/similar__text__unified_diff.snap b/src/text/snapshots/similar__text__unified_diff.snap
index aa8deb2..77f409a 100644
--- a/src/text/snapshots/similar__text__unified_diff.snap
+++ b/src/text/snapshots/similar__text__unified_diff.snap
@@ -4,7 +4,7 @@ expression: "&diff.unified_diff().context_radius(3).header(\"old\", \"new\").to_
 ---
 --- old
 +++ new
-@@ -0 +2 @@
+@@ -1,3 +1,3 @@
  Hello World
 -some stuff here
 +some amazing stuff here
diff --git a/src/udiff.rs b/src/udiff.rs
index 40969f2..80a30cf 100644
--- a/src/udiff.rs
+++ b/src/udiff.rs
@@ -24,7 +24,6 @@
 //! The former uses [`DiffableStr::to_string_lossy`], the latter uses
 //! [`DiffableStr::as_bytes`] for each line.
 #[cfg(feature = "text")]
-use std::ops::Range;
 use std::{fmt, io};
 
 use crate::iter::AllChangesIter;
@@ -46,10 +45,6 @@ impl fmt::Display for MissingNewlineHint {
 struct UnifiedDiffHunkRange(usize, usize);
 
 impl UnifiedDiffHunkRange {
-    fn new(range: Range<usize>) -> UnifiedDiffHunkRange {
-        UnifiedDiffHunkRange(range.start, range.end)
-    }
-
     fn start(&self) -> usize {
         self.0
     }
@@ -61,7 +56,7 @@ impl UnifiedDiffHunkRange {
 
 impl fmt::Display for UnifiedDiffHunkRange {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let mut beginning = self.start();
+        let mut beginning = self.start() + 1;
         let len = self.end() - self.start();
         if len == 1 {
             write!(f, "{}", beginning)
@@ -84,9 +79,15 @@ pub struct UnifiedHunkHeader {
 impl UnifiedHunkHeader {
     /// Creates a hunk header from a (non empty) slice of diff ops.
     pub fn new(ops: &[DiffOp]) -> UnifiedHunkHeader {
+        let first = ops[0];
+        let last = ops[ops.len() - 1];
+        let old_start = first.old_range().start;
+        let new_start = first.new_range().start;
+        let old_end = last.old_range().end;
+        let new_end = last.new_range().end;
         UnifiedHunkHeader {
-            old_range: UnifiedDiffHunkRange::new(ops[0].old_range()),
-            new_range: UnifiedDiffHunkRange::new(ops[ops.len() - 1].new_range()),
+            old_range: UnifiedDiffHunkRange(old_start, old_end),
+            new_range: UnifiedDiffHunkRange(new_start, new_end),
         }
     }
 }