patch 9.1.0099: Not able to use diff() with 'diffexpr'v9.1.0099

Problem:  Not able to use diff() with 'diffexpr'
          (rickhowe, after v9.1.0096)
Solution: Use a default context length of 0, update diff() help text,
          add a test for using diff() with 'diffexpr'
          (Yegappan Lakshmanan)

closes: #14013

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

7 files changed, 77 insertions, 24 deletions

diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 0dca4679e9..0b3d59e966 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2024 Feb 11
+*builtin.txt*	For Vim version 9.1.  Last change: 2024 Feb 12
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -2078,8 +2078,7 @@ diff({fromlist}, {tolist} [, {options}])		*diff()*
 					use.  Supported boolean items are
 					"myers", "minimal", "patience" and
 					"histogram".
-		    context		unified diff context length.  Default
-					is 1.
+		    context		diff context length.  Default is 0.
 		    iblank		ignore changes where lines are all
 					blank.
 		    icase		ignore changes in case of text.
@@ -2092,6 +2091,10 @@ diff({fromlist}, {tolist} [, {options}])		*diff()*
 					line.
 		For more information about these options, refer to 'diffopt'.
 
+		To compute the unified diff, all the items in {fromlist} are
+		concatenated into a string using a newline separator and the
+		same for {tolist}.  The unified diff output uses line numbers.
+
 		Returns an empty List or String if {fromlist} and {tolist} are
 		identical.
 
diff --git a/runtime/doc/diff.txt b/runtime/doc/diff.txt
index 05dd4a6be9..e3abbdeff5 100644
--- a/runtime/doc/diff.txt
+++ b/runtime/doc/diff.txt
@@ -510,9 +510,14 @@ between two Lists of strings are below.
    [{'from_idx': 1, 'from_count': 2, 'to_idx': 1, 'to_count': 0}]
 
   " disjointed changes
-  :echo diff(['ab', 'def', 'ghi', 'jkl'], ['abc', 'def', 'ghi', 'jk'], {'output': 'indices'})
+  :echo diff(['ab', 'def', 'ghi', 'jkl'], ['abc', 'def', 'ghi', 'jk'], {'output': 'indices', 'context': 0})
    [{'from_idx': 0, 'from_count': 1, 'to_idx': 0, 'to_count': 1},
     {'from_idx': 3, 'from_count': 1, 'to_idx': 3, 'to_count': 1}]
+
+  " disjointed changes with context length 1
+  :echo diff(['ab', 'def', 'ghi', 'jkl'], ['abc', 'def', 'ghi', 'jk'], {'output': 'indices', 'context': 1})
+   [{'from_idx': 0, 'from_count': 4, 'to_idx': 0, 'to_count': 4}]
+
 <
 
  vim:tw=78:ts=8:noet:ft=help:norl:
diff --git a/src/diff.c b/src/diff.c
index a4f3f7e072..d2089dc15e 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -3511,9 +3511,9 @@ parse_diff_optarg(
 	}
     }
 
-    *diff_ctxlen = dict_get_number_def(d, "context", 1);
+    *diff_ctxlen = dict_get_number_def(d, "context", 0);
     if (*diff_ctxlen < 0)
-	*diff_ctxlen = 1;
+	*diff_ctxlen = 0;
 
     if (dict_get_bool(d, "iblank", FALSE))
 	*diffopts |= DIFF_IBLANK;
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 67a14272b1..d13eb1c9f5 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1952,7 +1952,7 @@ static funcentry_T global_functions[] =
     {"did_filetype",	0, 0, 0,	    NULL,
 			ret_number_bool,    f_did_filetype},
     {"diff",		2, 3, FEARG_1,	    arg3_diff,
-			ret_list_dict_any,  f_diff},
+			ret_any,  f_diff},
     {"diff_filler",	1, 1, FEARG_1,	    arg1_lnum,
 			ret_number,	    f_diff_filler},
     {"diff_hlID",	2, 2, FEARG_1,	    arg2_lnum_number,
diff --git a/src/testdir/dumps/Test_difffunc_diffexpr_1.dump b/src/testdir/dumps/Test_difffunc_diffexpr_1.dump
new file mode 100644
index 0000000000..b103cc8d29
--- /dev/null
+++ b/src/testdir/dumps/Test_difffunc_diffexpr_1.dump
@@ -0,0 +1,12 @@
+| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@34||+1#0000000#ffffff0| +0#0000e05#a8a8a8255@1|z+0#0000000#5fd7ff255|e|r|o| @30
+| +0#0000e05#a8a8a8255@1>o+0#0000000#ffffff0|n|e| @31||+1&&| +0#0000e05#a8a8a8255@1|o+0#0000000#ffffff0|n|e| @31
+| +0#0000e05#a8a8a8255@1|t+0#0000000#ffd7ff255|w|o|x+2&#ff404010| +0&#ffd7ff255@30||+1&#ffffff0| +0#0000e05#a8a8a8255@1|t+0#0000000#ffd7ff255|w|o| @31
+| +0#0000e05#a8a8a8255@1|t+0#0000000#ffffff0|h|r|e@1| @29||+1&&| +0#0000e05#a8a8a8255@1|t+0#0000000#ffffff0|h|r|e@1| @29
+| +0#0000e05#a8a8a8255@1|f+0#0000000#5fd7ff255|o|u|r| @30||+1&#ffffff0| +0#0000e05#a8a8a8255@1|-+0#4040ff13#afffff255@34
+|~+0&#ffffff0| @35||+1#0000000&|~+0#4040ff13&| @35
+|~| @35||+1#0000000&|~+0#4040ff13&| @35
+|~| @35||+1#0000000&|~+0#4040ff13&| @35
+|~| @35||+1#0000000&|~+0#4040ff13&| @35
+|~| @35||+1#0000000&|~+0#4040ff13&| @35
+|X+3#0000000&|d|i|f@2|u|n|c|2|.|t|x|t| @4|1|,|1| @11|A|l@1| |X+1&&|d|i|f@2|u|n|c|1|.|t|x|t| @4|1|,|1| @11|A|l@1
+|"+0&&|X|d|i|f@2|u|n|c|2|.|t|x|t|"| |4|L|,| |2|0|B| @50
diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index d37a9a28a5..8e7d5ce312 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -1719,43 +1719,43 @@ endfunc
 " Test for the diff() function
 def Test_diff_func()
   # string is added/removed/modified at the beginning
-  assert_equal("@@ -1 +1,2 @@\n+abc\n def\n",
+  assert_equal("@@ -0,0 +1 @@\n+abc\n",
                diff(['def'], ['abc', 'def'], {output: 'unified'}))
   assert_equal([{from_idx: 0, from_count: 0, to_idx: 0, to_count: 1}],
                diff(['def'], ['abc', 'def'], {output: 'indices'}))
-  assert_equal("@@ -1,2 +1 @@\n-abc\n def\n",
+  assert_equal("@@ -1 +0,0 @@\n-abc\n",
                diff(['abc', 'def'], ['def'], {output: 'unified'}))
   assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 0}],
                diff(['abc', 'def'], ['def'], {output: 'indices'}))
-  assert_equal("@@ -1,2 +1,2 @@\n-abc\n+abx\n def\n",
+  assert_equal("@@ -1 +1 @@\n-abc\n+abx\n",
                diff(['abc', 'def'], ['abx', 'def'], {output: 'unified'}))
   assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
                diff(['abc', 'def'], ['abx', 'def'], {output: 'indices'}))
 
   # string is added/removed/modified at the end
-  assert_equal("@@ -1 +1,2 @@\n abc\n+def\n",
+  assert_equal("@@ -1,0 +2 @@\n+def\n",
                diff(['abc'], ['abc', 'def'], {output: 'unified'}))
   assert_equal([{from_idx: 1, from_count: 0, to_idx: 1, to_count: 1}],
                diff(['abc'], ['abc', 'def'], {output: 'indices'}))
-  assert_equal("@@ -1,2 +1 @@\n abc\n-def\n",
+  assert_equal("@@ -2 +1,0 @@\n-def\n",
                diff(['abc', 'def'], ['abc'], {output: 'unified'}))
   assert_equal([{from_idx: 1, from_count: 1, to_idx: 1, to_count: 0}],
                diff(['abc', 'def'], ['abc'], {output: 'indices'}))
-  assert_equal("@@ -1,2 +1,2 @@\n abc\n-def\n+xef\n",
+  assert_equal("@@ -2 +2 @@\n-def\n+xef\n",
                diff(['abc', 'def'], ['abc', 'xef'], {output: 'unified'}))
   assert_equal([{from_idx: 1, from_count: 1, to_idx: 1, to_count: 1}],
                diff(['abc', 'def'], ['abc', 'xef'], {output: 'indices'}))
 
   # string is added/removed/modified in the middle
-  assert_equal("@@ -2,2 +2,3 @@\n 222\n+xxx\n 333\n",
+  assert_equal("@@ -2,0 +3 @@\n+xxx\n",
                diff(['111', '222', '333'], ['111', '222', 'xxx', '333'], {output: 'unified'}))
   assert_equal([{from_idx: 2, from_count: 0, to_idx: 2, to_count: 1}],
                diff(['111', '222', '333'], ['111', '222', 'xxx', '333'], {output: 'indices'}))
-  assert_equal("@@ -2,3 +2,2 @@\n 222\n-333\n 444\n",
+  assert_equal("@@ -3 +2,0 @@\n-333\n",
                diff(['111', '222', '333', '444'], ['111', '222', '444'], {output: 'unified'}))
   assert_equal([{from_idx: 2, from_count: 1, to_idx: 2, to_count: 0}],
                diff(['111', '222', '333', '444'], ['111', '222', '444'], {output: 'indices'}))
-  assert_equal("@@ -2,3 +2,3 @@\n 222\n-333\n+xxx\n 444\n",
+  assert_equal("@@ -3 +3 @@\n-333\n+xxx\n",
                diff(['111', '222', '333', '444'], ['111', '222', 'xxx', '444'], {output: 'unified'}))
   assert_equal([{from_idx: 2, from_count: 1, to_idx: 2, to_count: 1}],
                diff(['111', '222', '333', '444'], ['111', '222', 'xxx', '444'], {output: 'indices'}))
@@ -1795,10 +1795,12 @@ def Test_diff_func()
                diff(['abcd'], ['abc'], {output: 'unified'}))
   assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
                diff(['abcd'], ['abc'], {output: 'indices'}))
-  assert_equal("@@ -1 +1 @@\n-abc\n+abx\n",
-               diff(['abc'], ['abx'], {output: 'unified'}))
+  var diff_unified: string = diff(['abc'], ['abx'], {output: 'unified'})
+  assert_equal("@@ -1 +1 @@\n-abc\n+abx\n", diff_unified)
+  var diff_indices: list<dict<number>> =
+    diff(['abc'], ['abx'], {output: 'indices'})
   assert_equal([{from_idx: 0, from_count: 1, to_idx: 0, to_count: 1}],
-               diff(['abc'], ['abx'], {output: 'indices'}))
+               diff_indices)
 
   # partial string modification at the start and at the end.
   var fromlist =<< trim END
@@ -1825,17 +1827,18 @@ def Test_diff_func()
     three four
     five six
   END
-  assert_equal("@@ -1,3 +1,3 @@\n-one two\n+one abc two\n three four\n-five abc six\n+five six\n",
+  assert_equal("@@ -1 +1 @@\n-one two\n+one abc two\n@@ -3 +3 @@\n-five abc six\n+five six\n",
                diff(fromlist, tolist, {output: 'unified'}))
-  assert_equal([{from_idx: 0, from_count: 3, to_idx: 0, to_count: 3}],
+  assert_equal([{'from_count': 1, 'to_idx': 0, 'to_count': 1, 'from_idx': 0},
+                {'from_count': 1, 'to_idx': 2, 'to_count': 1, 'from_idx': 2}],
                diff(fromlist, tolist, {output: 'indices'}))
 
   # add/remove blank lines
-  assert_equal("@@ -1,4 +1,2 @@\n one\n-\n-\n two\n",
+  assert_equal("@@ -2,2 +1,0 @@\n-\n-\n",
                diff(['one', '', '', 'two'], ['one', 'two'], {output: 'unified'}))
   assert_equal([{from_idx: 1, from_count: 2, to_idx: 1, to_count: 0}],
                diff(['one', '', '', 'two'], ['one', 'two'], {output: 'indices'}))
-  assert_equal("@@ -1,2 +1,4 @@\n one\n+\n+\n two\n",
+  assert_equal("@@ -1,0 +2,2 @@\n+\n+\n",
                diff(['one', 'two'], ['one', '', '', 'two'], {output: 'unified'}))
   assert_equal([{'from_idx': 1, 'from_count': 0, 'to_idx': 1, 'to_count': 2}],
                diff(['one', 'two'], ['one', '', '', 'two'], {output: 'indices'}))
@@ -1911,7 +1914,7 @@ def Test_diff_func()
                diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 3}))
   assert_equal("@@ -1,3 +1,4 @@\n+x\n a\n b\n c\n",
                diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: 4}))
-  assert_equal("@@ -1 +1,2 @@\n+x\n a\n",
+  assert_equal("@@ -0,0 +1 @@\n+x\n",
                diff(['a', 'b', 'c'], ['x', 'a', 'b', 'c'], {context: -1}))
 
   # Error cases
@@ -1922,4 +1925,32 @@ def Test_diff_func()
   assert_fails('call diff(["a"], ["a"], {context: []})', 'E745: Using a List as a Number')
 enddef
 
+" Test for using the diff() function with 'diffexpr'
+func Test_diffexpr_with_diff_func()
+  CheckScreendump
+
+  let lines =<< trim END
+    def DiffFuncExpr()
+      var in: list<string> = readfile(v:fname_in)
+      var new: list<string> = readfile(v:fname_new)
+      var out: string = diff(in, new)
+      writefile(split(out, "\n"), v:fname_out)
+    enddef
+    set diffexpr=DiffFuncExpr()
+
+    edit Xdifffunc1.txt
+    diffthis
+    vert split Xdifffunc2.txt
+    diffthis
+  END
+  call writefile(lines, 'XsetupDiffFunc.vim', 'D')
+
+  call writefile(['zero', 'one', 'two', 'three'], 'Xdifffunc1.txt', 'D')
+  call writefile(['one', 'twox', 'three', 'four'], 'Xdifffunc2.txt', 'D')
+
+  let buf = RunVimInTerminal('-S XsetupDiffFunc.vim', {'rows': 12})
+  call VerifyScreenDump(buf, 'Test_difffunc_diffexpr_1', {})
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 7fd6982f3f..7a9172a667 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    99,
+/**/
     98,
 /**/
     97,