https://git.savannah.gnu.org/cgit/diffutils.git/patch/?id=ba08fbbb0ca5da455bf695236c57bc50e7faed50
https://github.com/NixOS/nixpkgs/pull/213421#issuecomment-1407749912

Fix 'diff -D' regression
--- a/src/diff.c
+++ b/src/diff.c
@@ -416,7 +416,7 @@ main (int argc, char **argv)
 	    char *base = b;
 	    int changes = 0;
 
-	    for (i = 0; i < sizeof sizeof C_ifdef_group_formats; i++)
+	    for (i = 0; i < sizeof C_ifdef_group_formats; i++)
 	      {
 		char ch = C_ifdef_group_formats[i];
 		switch (ch)