empty context lines don't have the prefixing space char

[correabuscar]

on gnu diff and git diff every empty context line has one space as the prefix for the line, thus the line isn't empty in the patch itself, for example:

(to see this, start selecting with the mouse from 3 to -4, u'll see the extra space)

gnu diff:

--- /tmp/a	2024-08-08 22:29:37.810523528 +0200
+++ /tmp/b	2024-08-08 22:29:41.627190227 +0200
@@ -2,4 +2,4 @@
 2
 3
 
-4
+5

git diff:

--- /tmp/a	2024-08-08 22:29:37.810523528 +0200
+++ /tmp/b	2024-08-08 22:29:41.627190227 +0200
@@ -2,4 +2,4 @@
 2
 3
 
-4
+5

diffy:

--- /tmp/a
+++ /tmp/b
@@ -2,4 +2,4 @@
 2
 3

-4
+5

However applying the patch works fine with either empty context line or prefixed with space context line. (at least, gnu patch does)

[correabuscar]

ok I see this was on purpose, so what I want (which I'll do locally) is:

diff --git a/src/patch/format.rs b/src/patch/format.rs
index ec998a80f076016f..2a606b3e321f0349 100644
--- a/src/patch/format.rs
+++ b/src/patch/format.rs
@@ -231,12 +231,8 @@
             write!(w, "{}", style.prefix())?;
         }

-        if sign == ' ' && line == b"\n" {
-            w.write_all(line)?;
-        } else {
             write!(w, "{}", sign)?;
             w.write_all(line)?;
-        }

         if self.f.with_color {
             write!(w, "{}", style.suffix())?;
@@ -263,11 +259,7 @@
             write!(f, "{}", style.prefix())?;
         }

-        if sign == ' ' && *line == "\n" {
-            write!(f, "{}", line)?;
-        } else {
             write!(f, "{}{}", sign, line)?;
-        }

         if self.f.with_color {
             write!(f, "{}", style.suffix())?;