vim-patch:9.0.2009: cmdline-completion for comma-separated options wrong (#25569)

Problem:  cmdline-completion for comma-separated options wrong
Solution: Fix command-line expansions for options with filenames with
          commas

Fix command-line expansions for options with filenames with commas

Cmdline expansion for option values that take a comma-separated list
of file names is currently not handling file names with commas as the
commas are not escaped. For such options, the commas in file names need
to be escaped (to differentiate from a comma that delimit the list
items). The escaped comma is unescaped in `copy_option_part()` during
option parsing.

Fix as follows:
- Cmdline completion for option values with comma-separated file/folder
  names will not start a new match when seeing `\\,` and will instead
  consider it as one value.
- File/folder regex matching will strip the `\\` when seeing `\\,` to
  make sure it can match the correct files/folders.
- The expanded value will escape `,` with `\\,`, similar to how spaces
  are escaped to make sure the option value is correct on the cmdline.

This fix also takes into account the fact that Win32 Vim handles file
name escaping differently. Typing '\,' for a file name results in it
being handled literally but in other platforms '\,' is interpreted as a
simple ',' and commas need to be escaped using '\\,' instead.

Also, make sure this new logic only applies to comma-separated options
like 'path'. Non-list options like 'set makeprg=<Tab>' and regular ex
commands like `:edit <Tab>` do not require escaping and will continue to
work.

Also fix up documentation to be clearer. The original docs are slightly
misleading in how it discusses triple slashes for 'tags'.

closes: vim/vim#13303
related: vim/vim#13301

https://github.com/vim/vim/commit/54844857fd6933fa4f6678e47610c4b9c9f7a091

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

8 files changed, 171 insertions, 28 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 07f4eb80c5..e2af4d5bc1 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -136,10 +136,26 @@ To include white space in a string option value it has to be preceded with a
 backslash.  To include a backslash you have to use two.  Effectively this
 means that the number of backslashes in an option value is halved (rounded
 down).
+In options 'path', 'cdpath', and 'tags', spaces have to be preceded with three
+backslashes instead becuase they can be separated by either commas or spaces.
+Comma-separated options like 'backupdir' and 'tags' will also require commas
+to be escaped with two backslashes, whereas this is not needed for
+non-comma-separated ones like 'makeprg'.
+When setting options using |:let| and |literal-string|, you need to use one
+fewer layer of backslash.
 A few examples: >
-   :set tags=tags\ /usr/tags	    results in "tags /usr/tags"
-   :set tags=tags\\,file	    results in "tags\,file"
-   :set tags=tags\\\ file	    results in "tags\ file"
+   :set makeprg=make\ file	    results in "make file"
+   :let &makeprg='make file'	    (same as above)
+   :set makeprg=make\\\ file	    results in "make\ file"
+   :set tags=tags\ /usr/tags	    results in "tags" and "/usr/tags"
+   :set tags=tags\\\ file	    results in "tags file"
+   :let &tags='tags\ file'	    (same as above)
+
+   :set makeprg=make,file	    results in "make,file"
+   :set makeprg=make\\,file	    results in "make\,file"
+   :set tags=tags,file		    results in "tags" and "file"
+   :set tags=tags\\,file	    results in "tags,file"
+   :let &tags='tags\,file'	    (same as above)
 
 The "|" character separates a ":set" command from a following command.  To
 include the "|" in the option value, use "\|" instead.  This example sets the
@@ -6426,8 +6442,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 'tags' 'tag'		string	(default "./tags;,tags")
 			global or local to buffer |global-local|
 	Filenames for the tag command, separated by spaces or commas.  To
-	include a space or comma in a file name, precede it with a backslash
-	(see |option-backslash| about including spaces and backslashes).
+	include a space or comma in a file name, precede it with backslashes
+	(see |option-backslash| about including spaces/commas and backslashes).
 	When a file name starts with "./", the '.' is replaced with the path
 	of the current file.  But only when the 'd' flag is not included in
 	'cpoptions'.  Environment variables are expanded |:set_env|.  Also see
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index 4f6408b136..a4e0e61248 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -6877,8 +6877,8 @@ vim.go.tagrelative = vim.o.tagrelative
 vim.go.tr = vim.go.tagrelative
 
 --- Filenames for the tag command, separated by spaces or commas.  To
---- include a space or comma in a file name, precede it with a backslash
---- (see `option-backslash` about including spaces and backslashes).
+--- include a space or comma in a file name, precede it with backslashes
+--- (see `option-backslash` about including spaces/commas and backslashes).
 --- When a file name starts with "./", the '.' is replaced with the path
 --- of the current file.  But only when the 'd' flag is not included in
 --- 'cpoptions'.  Environment variables are expanded `:set_env`.  Also see
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index c2469b6574..38be6573c8 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -156,8 +156,9 @@ static void wildescape(expand_T *xp, const char *str, int numfiles, char **files
     // and wildmatch characters, except '~'.
     for (int i = 0; i < numfiles; i++) {
       // for ":set path=" we need to escape spaces twice
-      if (xp->xp_backslash == XP_BS_THREE) {
-        p = vim_strsave_escaped(files[i], " ");
+      if (xp->xp_backslash & XP_BS_THREE) {
+        char *pat = (xp->xp_backslash & XP_BS_COMMA) ? " ," : " ";
+        p = vim_strsave_escaped(files[i], pat);
         xfree(files[i]);
         files[i] = p;
 #if defined(BACKSLASH_IN_FILENAME)
@@ -165,6 +166,14 @@ static void wildescape(expand_T *xp, const char *str, int numfiles, char **files
         xfree(files[i]);
         files[i] = p;
 #endif
+      } else if (xp->xp_backslash & XP_BS_COMMA) {
+        if (vim_strchr(files[i], ',') != NULL) {
+          p = vim_strsave_escaped(files[i], ",");
+          if (p != NULL) {
+            xfree(files[i]);
+            files[i] = p;
+          }
+        }
       }
 #ifdef BACKSLASH_IN_FILENAME
       p = vim_strsave_fnameescape(files[i], vse_what);
@@ -2440,15 +2449,23 @@ static int expand_files_and_dirs(expand_T *xp, char *pat, char ***matches, int *
     pat = xstrdup(pat);
     for (int i = 0; pat[i]; i++) {
       if (pat[i] == '\\') {
-        if (xp->xp_backslash == XP_BS_THREE
+        if (xp->xp_backslash & XP_BS_THREE
             && pat[i + 1] == '\\'
             && pat[i + 2] == '\\'
             && pat[i + 3] == ' ') {
           STRMOVE(pat + i, pat + i + 3);
-        }
-        if (xp->xp_backslash == XP_BS_ONE
-            && pat[i + 1] == ' ') {
+        } else if (xp->xp_backslash & XP_BS_ONE
+                   && pat[i + 1] == ' ') {
           STRMOVE(pat + i, pat + i + 1);
+        } else if ((xp->xp_backslash & XP_BS_COMMA)
+                   && pat[i + 1] == '\\'
+                   && pat[i + 2] == ',') {
+          STRMOVE(pat + i, pat + i + 2);
+#ifdef BACKSLASH_IN_FILENAME
+        } else if ((xp->xp_backslash & XP_BS_COMMA)
+                   && pat[i + 1] == ',') {
+          STRMOVE(pat + i, pat + i + 1);
+#endif
         }
       }
     }
diff --git a/src/nvim/cmdexpand_defs.h b/src/nvim/cmdexpand_defs.h
index a302a32852..7c422aca18 100644
--- a/src/nvim/cmdexpand_defs.h
+++ b/src/nvim/cmdexpand_defs.h
@@ -40,9 +40,10 @@ typedef struct expand {
 
 /// values for xp_backslash
 enum {
-  XP_BS_NONE  = 0,  ///< nothing special for backslashes
-  XP_BS_ONE   = 1,  ///< uses one backslash before a space
-  XP_BS_THREE = 2,  ///< uses three backslashes before a space
+  XP_BS_NONE  = 0,    ///< nothing special for backslashes
+  XP_BS_ONE   = 0x1,  ///< uses one backslash before a space
+  XP_BS_THREE = 0x2,  ///< uses three backslashes before a space
+  XP_BS_COMMA = 0x4,  ///< commas need to be escaped with a backslash
 };
 
 /// values for xp_context when doing command line completion
diff --git a/src/nvim/option.c b/src/nvim/option.c
index c0353e52be..0700d0e87e 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -5496,6 +5496,9 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
         xp->xp_backslash = XP_BS_ONE;
       }
     }
+    if (flags & P_COMMA) {
+      xp->xp_backslash |= XP_BS_COMMA;
+    }
   }
 
   // For an option that is a list of file names, or comma/colon-separated
@@ -5511,8 +5514,12 @@ void set_context_in_set_cmd(expand_T *xp, char *arg, int opt_flags)
         while (s > xp->xp_pattern && *(s - 1) == '\\') {
           s--;
         }
-        if ((*p == ' ' && (xp->xp_backslash == XP_BS_THREE && (p - s) < 3))
-            || (*p == ',' && (flags & P_COMMA) && ((p - s) % 1) == 0)
+        if ((*p == ' ' && ((xp->xp_backslash & XP_BS_THREE) && (p - s) < 3))
+#if defined(BACKSLASH_IN_FILENAME)
+            || (*p == ',' && (flags & P_COMMA) && (p - s) < 1)
+#else
+            || (*p == ',' && (flags & P_COMMA) && (p - s) < 2)
+#endif
             || (*p == ':' && (flags & P_COLON))) {
           xp->xp_pattern = p + 1;
           break;
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 68d88ea0aa..d5f41c5a89 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -8679,8 +8679,8 @@ return {
       deny_duplicates = true,
       desc = [=[
         Filenames for the tag command, separated by spaces or commas.  To
-        include a space or comma in a file name, precede it with a backslash
-        (see |option-backslash| about including spaces and backslashes).
+        include a space or comma in a file name, precede it with backslashes
+        (see |option-backslash| about including spaces/commas and backslashes).
         When a file name starts with "./", the '.' is replaced with the path
         of the current file.  But only when the 'd' flag is not included in
         'cpoptions'.  Environment variables are expanded |:set_env|.  Also see
diff --git a/test/old/testdir/test_cmdline.vim b/test/old/testdir/test_cmdline.vim
index 54f5dd500b..90748a6076 100644
--- a/test/old/testdir/test_cmdline.vim
+++ b/test/old/testdir/test_cmdline.vim
@@ -1176,13 +1176,71 @@ func Test_cmdline_complete_various()
   mapclear
   delcom MyCmd
 
+  " Prepare for path completion
+  call mkdir('Xa b c', 'D')
+  defer delete('Xcomma,foobar.txt')
+  call writefile([], 'Xcomma,foobar.txt')
+
   " completion for :set path= with multiple backslashes
-  call feedkeys(":set path=a\\\\\\ b\<C-A>\<C-B>\"\<CR>", 'xt')
-  call assert_equal('"set path=a\\\ b', @:)
+  call feedkeys(':set path=Xa\\\ b' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"set path=Xa\\\ b\\\ c/', @:)
+  set path&
 
   " completion for :set dir= with a backslash
-  call feedkeys(":set dir=a\\ b\<C-A>\<C-B>\"\<CR>", 'xt')
-  call assert_equal('"set dir=a\ b', @:)
+  call feedkeys(':set dir=Xa\ b' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"set dir=Xa\ b\ c/', @:)
+  set dir&
+
+  " completion for :set tags= / set dictionary= with escaped commas
+  if has('win32')
+    " In Windows backslashes are rounded up, so both '\,' and '\\,' escape to
+    " '\,'
+    call feedkeys(':set dictionary=Xcomma\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set dictionary=Xcomma\,foobar.txt', @:)
+
+    call feedkeys(':set tags=Xcomma\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set tags=Xcomma\,foobar.txt', @:)
+
+    call feedkeys(':set tags=Xcomma\\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set tags=Xcomma\\\,foo', @:) " Didn't find a match
+
+    " completion for :set dictionary= with escaped commas (same behavior, but
+    " different internal code path from 'set tags=' for escaping the output)
+    call feedkeys(':set tags=Xcomma\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set tags=Xcomma\,foobar.txt', @:)
+  else
+    " In other platforms, backslashes are rounded down (since '\,' itself will
+    " be escaped into ','). As a result '\\,' and '\\\,' escape to '\,'.
+    call feedkeys(':set tags=Xcomma\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set tags=Xcomma\,foo', @:) " Didn't find a match
+
+    call feedkeys(':set tags=Xcomma\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set tags=Xcomma\\,foobar.txt', @:)
+
+    call feedkeys(':set dictionary=Xcomma\\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set dictionary=Xcomma\\,foobar.txt', @:)
+
+    " completion for :set dictionary= with escaped commas (same behavior, but
+    " different internal code path from 'set tags=' for escaping the output)
+    call feedkeys(':set dictionary=Xcomma\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set dictionary=Xcomma\\,foobar.txt', @:)
+  endif
+  set tags&
+  set dictionary&
+
+  " completion for :set makeprg= with no escaped commas
+  call feedkeys(':set makeprg=Xcomma,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal('"set makeprg=Xcomma,foobar.txt', @:)
+
+  if !has('win32')
+    " Cannot create file with backslash in file name in Windows, so only test
+    " this elsewhere.
+    defer delete('Xcomma\,fooslash.txt')
+    call writefile([], 'Xcomma\,fooslash.txt')
+    call feedkeys(':set makeprg=Xcomma\\,foo' .. "\<C-A>\<C-B>\"\<CR>", 'xt')
+    call assert_equal('"set makeprg=Xcomma\\,fooslash.txt', @:)
+  endif
+  set makeprg&
 
   " completion for the :py3 commands
   call feedkeys(":py3\<C-A>\<C-B>\"\<CR>", 'xt')
diff --git a/test/old/testdir/test_options.vim b/test/old/testdir/test_options.vim
index 76b7cc920b..cc3f21b86b 100644
--- a/test/old/testdir/test_options.vim
+++ b/test/old/testdir/test_options.vim
@@ -316,16 +316,60 @@ func Test_set_completion()
 
   " Expand directories.
   call feedkeys(":set cdpath=./\<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_match('./samples/ ', @:)
-  call assert_notmatch('./small.vim ', @:)
+  call assert_match(' ./samples/ ', @:)
+  call assert_notmatch(' ./summarize.vim ', @:)
+  set cdpath&
 
   " Expand files and directories.
   call feedkeys(":set tags=./\<C-A>\<C-B>\"\<CR>", 'tx')
-  call assert_match('./samples/ ./sautest/ ./screendump.vim ./script_util.vim ./setup.vim ./shared.vim', @:)
+  call assert_match(' ./samples/.* ./summarize.vim', @:)
 
   call feedkeys(":set tags=./\\\\ dif\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"set tags=./\\ diff diffexpr diffopt', @:)
-  set tags&
+
+  " Expand files with spaces/commas in them. Make sure we delimit correctly.
+  "
+  " 'tags' allow for for spaces/commas to both act as delimiters, with actual
+  " spaces requiring double escape, and commas need a single escape.
+  " 'dictionary' is a normal comma-separated option where only commas act as
+  " delimiters, and both space/comma need one single escape.
+  " 'makeprg' is a non-comma-separated option. Commas don't need escape.
+  defer delete('Xfoo Xspace.txt')
+  defer delete('Xsp_dummy')
+  defer delete('Xbar,Xcomma.txt')
+  defer delete('Xcom_dummy')
+  call writefile([], 'Xfoo Xspace.txt')
+  call writefile([], 'Xsp_dummy')
+  call writefile([], 'Xbar,Xcomma.txt')
+  call writefile([], 'Xcom_dummy')
+
+  call feedkeys(':set tags=./Xfoo\ Xsp' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set tags=./Xfoo\ Xsp_dummy', @:)
+  call feedkeys(':set tags=./Xfoo\\\ Xsp' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set tags=./Xfoo\\\ Xspace.txt', @:)
+  call feedkeys(':set dictionary=./Xfoo\ Xsp' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set dictionary=./Xfoo\ Xspace.txt', @:)
+
+  call feedkeys(':set dictionary=./Xbar,Xcom' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set dictionary=./Xbar,Xcom_dummy', @:)
+  if has('win32')
+    " In Windows, '\,' is literal, see `:help filename-backslash`, so this
+    " means we treat it as one file name.
+    call feedkeys(':set dictionary=Xbar\,Xcom' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+    call assert_equal('"set dictionary=Xbar\,Xcomma.txt', @:)
+  else
+    " In other platforms, '\,' simply escape to ',', and indicate a delimiter
+    " to split into a separate file name. You need '\\,' to escape the comma
+    " as part of the file name.
+    call feedkeys(':set dictionary=Xbar\,Xcom' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+    call assert_equal('"set dictionary=Xbar\,Xcom_dummy', @:)
+
+    call feedkeys(':set dictionary=Xbar\\,Xcom' .. "\<C-A>\<C-B>\"\<CR>", 'tx')
+    call assert_equal('"set dictionary=Xbar\\,Xcomma.txt', @:)
+  endif
+  call feedkeys(":set makeprg=./Xbar,Xcom\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set makeprg=./Xbar,Xcomma.txt', @:)
+  set tags& dictionary& makeprg&
 
   " Expanding the option names
   call feedkeys(":set \<Tab>\<C-B>\"\<CR>", 'xt')