patch 9.1.1600: using diff anchors with hidden buffers fails silently

Problem:  diff: using diff anchors with hidden buffers fails silently
Solution: Give specific error message for diff anchors when using hidden
          buffers (Yee Cheng Chin).

Diff anchors currently will fail to parse if a buffer used for diff'ing
is hidden. Previously it would just fail as the code assumes it would
not happen normally, but this is actually possible to do if `closeoff`
and `hideoff` are not set in diffopt. Git's default diff tool "vimdiff3"
also takes advantage of this.

This fix this properly would require the `{address}` parser to be
smarter about whether a particular address relies on window position or
not (e.g. the `'.` address requires an active window, but `'a` or `1234`
do not). Since hidden diff buffers seem relatively niche, just provide a
better error message / documentation for now. This could be improved
later if there's a demand for it.

related: #17615
closes: #17904

Signed-off-by: Yee Cheng Chin <ychin.git@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 7a12ee12b6903290460312dc617c420dcd168641..b22a1711dc3b27bff61b147bf2ec47c67bc9d6a2 100644 (file)
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*  For Vim version 9.1.  Last change: 2025 Aug 06
+*options.txt*  For Vim version 9.1.  Last change: 2025 Aug 07
 
 
                  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -3016,6 +3016,8 @@ A jump table for the options with a short description can be found at |Q_op|.
        If some of the {address} do not resolve to a line in each buffer (e.g.
        a pattern search that does not match anything), none of the anchors
        will be used.
+                                                               *E1562*
+       Diff anchors can only be used when there are no hidden diff buffers.
 
                                                *'dex'* *'diffexpr'*
 'diffexpr' 'dex'       string  (default "")

diff --git a/runtime/doc/tags b/runtime/doc/tags
index 116682504bae53d04a247657af2b1b59f7041a9a..d94bc5ba94eb50ea34babf944e16f101e712d3cf 100644 (file)
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -4694,6 +4694,7 @@ E1559     vim9.txt        /*E1559*
 E156   sign.txt        /*E156*
 E1560  vim9.txt        /*E1560*
 E1561  vim9.txt        /*E1561*
+E1562  options.txt     /*E1562*
 E157   sign.txt        /*E157*
 E158   sign.txt        /*E158*
 E159   sign.txt        /*E159*

diff --git a/src/diff.c b/src/diff.c
index d86dbf153033409e416bde1e138c5f9819e1b0b4..b8d9de539d404d2d1bedd23d24a4682b9e7b9bc2 100644 (file)
--- a/src/diff.c
+++ b/src/diff.c
@@ -2768,8 +2768,15 @@ parse_diffanchors(int check_only, buf_T *buf, linenr_T *anchors, int *num_anchor
        FOR_ALL_WINDOWS(bufwin)
            if (bufwin->w_buffer == buf && bufwin->w_p_diff)
                break;
-       if (bufwin == NULL)
-           return FAIL; // should not really happen
+       if (bufwin == NULL && *dia != NUL)
+       {
+           // The buffer is hidden. Currently this is not supported due to the
+           // edge cases of needing to decide if an address is window-specific
+           // or not. We could add more checks in the future so we can detect
+           // whether an address relies on curwin to make this more fleixble.
+           emsg(_(e_diff_anchors_with_hidden_windows));
+           return FAIL;
+       }
     }
 
     for (i = 0; i < MAX_DIFF_ANCHORS && *dia != NUL; i++)

diff --git a/src/errors.h b/src/errors.h
index 8bb5214929a83fa10201b223adaf27ac3dbeac7e..050fb42199e9ea3f1dc58237c80e80bc88334d78 100644 (file)
--- a/src/errors.h
+++ b/src/errors.h
@@ -3778,3 +3778,7 @@ EXTERN char e_not_a_generic_function_str[]
 EXTERN char e_duplicate_type_var_name_str[]
        INIT(= N_("E1561: Duplicate type variable name: %s"));
 #endif
+#if defined(FEAT_DIFF)
+EXTERN char e_diff_anchors_with_hidden_windows[]
+       INIT(= N_("E1562: Diff anchors cannot be used with hidden diff windows"));
+#endif

diff --git a/src/po/vim.pot b/src/po/vim.pot
index cdb2e2ea2eb5503306c0e6abe515f697ad649f94..5b9ba3cd8938389b1029a9828d52aa910ec32fa6 100644 (file)
--- a/src/po/vim.pot
+++ b/src/po/vim.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2025-07-25 19:14+0200\n"
+"POT-Creation-Date: 2025-08-07 15:32+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -8803,6 +8803,9 @@ msgstr ""
 msgid "E1561: Duplicate type variable name: %s"
 msgstr ""
 
+msgid "E1562: Diff anchors cannot be used with hidden diff windows"
+msgstr ""
+
 #. type of cmdline window or 0
 #. result of cmdline window or 0
 #. buffer of cmdline window or NULL

diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index eee23729a1fd77ae7f3bca1523628bb552de1ae3..5ea7a7c8a0db6d13745924f1ef668eecd94a7b8c 100644 (file)
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -3483,6 +3483,10 @@ func Test_diffanchors_invalid()
   call assert_fails('diffupdate', 'E1550:')
   call assert_equal('orig_search_pat', @/)
 
+  " Hidden buffers are not supported right now
+  hide
+  call assert_fails('diffupdate', 'E1562:')
+
   %bw!
   set diffopt&
   set diffanchors&

diff --git a/src/version.c b/src/version.c
index d1923b1dbe70ec93428512eca285f3954699373e..3f3f1e1b63ac3ccdd871a316add72aa6414b36e9 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1600,
 /**/
     1599,
 /**/