patch 9.1.0774: "shellcmdline" doesn't work with getcompletion()

Problem:  "shellcmdline" doesn't work with getcompletion().
Solution: Use set_context_for_wildcard_arg() (zeertzjq).

closes: #15834

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/cmdexpand.c b/src/cmdexpand.c
index e563d22..3f74f47 100644
--- a/src/cmdexpand.c
+++ b/src/cmdexpand.c
@@ -1721,7 +1721,7 @@
 	// characters that end the command and white space.
 	else if (c == '|' || c == '\n' || c == '"' || (VIM_ISWHITE(c)
 #ifdef SPACE_IN_FILENAME
-		    && (!(eap->argt & EX_NOSPC) || usefilter)
+		    && (!(eap != NULL && (eap->argt & EX_NOSPC)) || usefilter)
 #endif
 		    ))
 	{
@@ -1756,7 +1756,10 @@
     xp->xp_context = EXPAND_FILES;
 
     // For a shell command more chars need to be escaped.
-    if (usefilter || eap->cmdidx == CMD_bang || eap->cmdidx == CMD_terminal || *complp == EXPAND_SHELLCMDLINE)
+    if (usefilter
+	    || (eap != NULL
+		&& (eap->cmdidx == CMD_bang || eap->cmdidx == CMD_terminal))
+	    || *complp == EXPAND_SHELLCMDLINE)
     {
 #ifndef BACKSLASH_IN_FILENAME
 	xp->xp_shell = TRUE;
@@ -4208,6 +4211,13 @@
 	    set_context_in_runtime_cmd(&xpc, xpc.xp_pattern);
 	    xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
 	}
+	if (xpc.xp_context == EXPAND_SHELLCMDLINE)
+	{
+	    int context = EXPAND_SHELLCMDLINE;
+	    set_context_for_wildcard_arg(NULL, xpc.xp_pattern, FALSE, &xpc,
+								     &context);
+	    xpc.xp_pattern_len = (int)STRLEN(xpc.xp_pattern);
+	}
     }
 
     if (cmdline_fuzzy_completion_supported(&xpc))
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 418dafa..e1dbc87 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -1084,6 +1084,8 @@
 
   call feedkeys(":MyCmd whoam\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_match('^".*\<whoami\>', @:)
+  let l = getcompletion('whoam', 'shellcmdline')
+  call assert_match('\<whoami\>', join(l, ' '))
 
   delcommand MyCmd
 endfunc
@@ -3649,9 +3651,13 @@
 
   call feedkeys(":MyCmd vim test_cmdline.\<Tab>\<C-B>\"\<CR>", 'xt')
   call assert_equal('"MyCmd vim test_cmdline.vim', @:)
+  call assert_equal(['test_cmdline.vim'],
+        \ getcompletion('vim test_cmdline.', 'shellcmdline'))
 
   call feedkeys(":MyCmd vim nonexistentfile\<Tab>\<C-B>\"\<CR>", 'xt')
   call assert_equal('"MyCmd vim nonexistentfile', @:)
+  call assert_equal([],
+        \ getcompletion('vim nonexistentfile', 'shellcmdline'))
 
   let compl1 = getcompletion('', 'file')[0]
   let compl2 = getcompletion('', 'file')[1]
@@ -3668,9 +3674,13 @@
   set wildoptions&
   call feedkeys(":MyCmd vim test_cmdline.\<Tab>\<C-B>\"\<CR>", 'xt')
   call assert_equal('"MyCmd vim test_cmdline.vim', @:)
+  call assert_equal(['test_cmdline.vim'],
+        \ getcompletion('vim test_cmdline.', 'shellcmdline'))
 
   call feedkeys(":MyCmd vim nonexistentfile\<Tab>\<C-B>\"\<CR>", 'xt')
   call assert_equal('"MyCmd vim nonexistentfile', @:)
+  call assert_equal([],
+        \ getcompletion('vim nonexistentfile', 'shellcmdline'))
 
   let compl1 = getcompletion('', 'file')[0]
   let compl2 = getcompletion('', 'file')[1]
diff --git a/src/version.c b/src/version.c
index 905daf9..aa53d0a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    774,
+/**/
     773,
 /**/
     772,