vim-patch:9.1.0821: 'findexpr' completion doesn't set v:fname to cmdline argument

Problem:  'findexpr' completion doesn't set v:fname to cmdline argument.
Solution: Set v:fname to the cmdline argument as-is (zeertzjq).

closes: vim/vim#15934

https://github.com/vim/vim/commit/20e045f78148c0ef0143c33ffe686fee72d29376

4 files changed, 22 insertions, 2 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 441f180177..7f95a19918 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -2611,6 +2611,10 @@ A jump table for the options with a short description can be found at |Q_op|.
 	The expression is evaluated only once per |:find| command invocation.
 	The expression can process all the directories specified in 'path'.
 
+	The expression may be evaluated for command-line completion as well,
+	in which case the |v:cmdcomplete| variable will be set to |v:true|,
+	otherwise it will be set to |v:false|.
+
 	If a match is found, the expression should return a |List| containing
 	one or more file names.  If a match is not found, the expression
 	should return an empty List.
@@ -2630,7 +2634,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	>vim
 	    " Use glob()
 	    func FindExprGlob()
-		return glob(v:fname, v:false, v:true)
+		let pat = v:cmdcomplete ? $'{v:fname}*' : v:fname
+		return glob(pat, v:false, v:true)
 	    endfunc
 	    set findexpr=FindExprGlob()
 
diff --git a/runtime/doc/vvars.txt b/runtime/doc/vvars.txt
index 3f9ce8cc96..1c1d88c29c 100644
--- a/runtime/doc/vvars.txt
+++ b/runtime/doc/vvars.txt
@@ -48,6 +48,11 @@ v:cmdbang
 		can only be used in autocommands.  For user commands |<bang>|
 		can be used.
 
+				*v:cmdcomplete* *cmdcomplete-variable*
+v:cmdcomplete
+		When evaluating 'findexpr': if 'findexpr' is used for cmdline
+		completion the value is |v:true|, otherwise it is |v:false|.
+
 					*v:collate* *collate-variable*
 v:collate
 		The current locale setting for collation order of the runtime
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index 8d5601ff6a..710f82bf21 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -2304,6 +2304,10 @@ vim.go.fcs = vim.go.fillchars
 --- The expression is evaluated only once per `:find` command invocation.
 --- The expression can process all the directories specified in 'path'.
 ---
+--- The expression may be evaluated for command-line completion as well,
+--- in which case the `v:cmdcomplete` variable will be set to `v:true`,
+--- otherwise it will be set to `v:false`.
+---
 --- If a match is found, the expression should return a `List` containing
 --- one or more file names.  If a match is not found, the expression
 --- should return an empty List.
@@ -2324,7 +2328,8 @@ vim.go.fcs = vim.go.fillchars
 --- ```vim
 ---     " Use glob()
 ---     func FindExprGlob()
---- 	return glob(v:fname, v:false, v:true)
+--- 	let pat = v:cmdcomplete ? $'{v:fname}*' : v:fname
+--- 	return glob(pat, v:false, v:true)
 ---     endfunc
 ---     set findexpr=FindExprGlob()
 ---
diff --git a/runtime/lua/vim/_meta/vvars.lua b/runtime/lua/vim/_meta/vvars.lua
index cba200101b..b104356334 100644
--- a/runtime/lua/vim/_meta/vvars.lua
+++ b/runtime/lua/vim/_meta/vvars.lua
@@ -44,6 +44,11 @@ vim.v.cmdarg = ...
 --- @type integer
 vim.v.cmdbang = ...
 
+--- When evaluating 'findexpr': if 'findexpr' is used for cmdline
+--- completion the value is `v:true`, otherwise it is `v:false`.
+--- @type boolean
+vim.v.cmdcomplete = ...
+
 --- The current locale setting for collation order of the runtime
 --- environment.  This allows Vim scripts to be aware of the
 --- current locale encoding.  Technical: it's the value of