patch 8.2.4617: no completion for :scriptnames

Problem:    No completion for :scriptnames.
Solution:   Implement :scriptnames completion. (Yegappan Lakshmanan,
            closes #10005)
diff --git a/src/cmdexpand.c b/src/cmdexpand.c
index defc282..ca669c0 100644
--- a/src/cmdexpand.c
+++ b/src/cmdexpand.c
@@ -1709,6 +1709,24 @@
 
     return NULL;
 }
+
+    static char_u *
+set_context_in_scriptnames_cmd(expand_T *xp, char_u *arg)
+{
+    char_u *p;
+
+    xp->xp_context = EXPAND_NOTHING;
+    xp->xp_pattern = NULL;
+
+    p = skipwhite(arg);
+    if (VIM_ISDIGIT(*p))
+	return NULL;
+
+    xp->xp_context = EXPAND_SCRIPTNAMES;
+    xp->xp_pattern = p;
+
+    return NULL;
+}
 #endif
 
 /*
@@ -2072,6 +2090,9 @@
 	case CMD_profdel:
 	case CMD_breakdel:
 	    return set_context_in_breakadd_cmd(xp, arg, cmdidx);
+
+	case CMD_scriptnames:
+	    return set_context_in_scriptnames_cmd(xp, arg);
 #endif
 
 	default:
@@ -2495,6 +2516,23 @@
     }
     return NULL;
 }
+
+/*
+ * Function given to ExpandGeneric() to obtain the possible arguments for the
+ * ":scriptnames" command.
+ */
+    static char_u *
+get_scriptnames_arg(expand_T *xp UNUSED, int idx)
+{
+    scriptitem_T *si;
+
+    if (!SCRIPT_ID_VALID(idx + 1))
+	return NULL;
+
+    si = SCRIPT_ITEM(idx + 1);
+    home_replace(NULL, si->sn_name, NameBuff, MAXPATHL, TRUE);
+    return NameBuff;
+}
 #endif
 
 /*
@@ -2584,6 +2622,7 @@
 	{EXPAND_ARGLIST, get_arglist_name, TRUE, FALSE},
 #ifdef FEAT_EVAL
 	{EXPAND_BREAKPOINT, get_breakadd_arg, TRUE, TRUE},
+	{EXPAND_SCRIPTNAMES, get_scriptnames_arg, TRUE, FALSE},
 #endif
     };
     int	i;
@@ -2791,6 +2830,8 @@
     int		score = 0;
     int		fuzzy;
     int		match;
+    int		sort_matches = FALSE;
+    int		funcsort = FALSE;
 
     fuzzy = cmdline_fuzzy_complete(pat);
     *matches = NULL;
@@ -2878,14 +2919,25 @@
     if (ga.ga_len == 0)
 	return OK;
 
-    // Sort the results.  Keep menu's in the specified order.
+    // sort the matches when using regular expression matching and sorting
+    // applies to the completion context. Menus and scriptnames should be kept
+    // in the specified order.
     if (!fuzzy && xp->xp_context != EXPAND_MENUNAMES
-					&& xp->xp_context != EXPAND_MENUS)
+					&& xp->xp_context != EXPAND_MENUS
+					&& xp->xp_context != EXPAND_SCRIPTNAMES)
+	sort_matches = TRUE;
+
+    // <SNR> functions should be sorted to the end.
+    if (xp->xp_context == EXPAND_EXPRESSION
+	    || xp->xp_context == EXPAND_FUNCTIONS
+	    || xp->xp_context == EXPAND_USER_FUNC
+	    || xp->xp_context == EXPAND_DISASSEMBLE)
+	funcsort = TRUE;
+
+    // Sort the matches.
+    if (sort_matches)
     {
-	if (xp->xp_context == EXPAND_EXPRESSION
-		|| xp->xp_context == EXPAND_FUNCTIONS
-		|| xp->xp_context == EXPAND_USER_FUNC
-		|| xp->xp_context == EXPAND_DISASSEMBLE)
+	if (funcsort)
 	    // <SNR> functions should be sorted to the end.
 	    qsort((void *)ga.ga_data, (size_t)ga.ga_len, sizeof(char_u *),
 							   sort_func_compare);
@@ -2900,15 +2952,6 @@
     }
     else
     {
-	int	funcsort = FALSE;
-
-	if (xp->xp_context == EXPAND_EXPRESSION
-		|| xp->xp_context == EXPAND_FUNCTIONS
-		|| xp->xp_context == EXPAND_USER_FUNC
-		|| xp->xp_context == EXPAND_DISASSEMBLE)
-	    // <SNR> functions should be sorted to the end.
-	    funcsort = TRUE;
-
 	if (fuzzymatches_to_strmatches(ga.ga_data, matches, ga.ga_len,
 							funcsort) == FAIL)
 	    return FAIL;
diff --git a/src/ex_cmds.h b/src/ex_cmds.h
index c8ebcf6..e4f9bb0 100644
--- a/src/ex_cmds.h
+++ b/src/ex_cmds.h
@@ -1356,7 +1356,7 @@
 	EX_CMDARG|EX_TRLBAR,
 	ADDR_NONE),
 EXCMD(CMD_scriptnames,	"scriptnames",	ex_scriptnames,
-	EX_BANG|EX_RANGE|EX_COUNT|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
+	EX_BANG|EX_FILES|EX_RANGE|EX_COUNT|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
 	ADDR_OTHER),
 EXCMD(CMD_scriptencoding, "scriptencoding", ex_scriptencoding,
 	EX_WORD1|EX_TRLBAR|EX_CMDWIN|EX_LOCK_OK,
diff --git a/src/scriptfile.c b/src/scriptfile.c
index ae46e7a..a334b2f 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -1769,14 +1769,20 @@
 {
     int i;
 
-    if (eap->addr_count > 0)
+    if (eap->addr_count > 0 || *eap->arg != NUL)
     {
 	// :script {scriptId}: edit the script
-	if (!SCRIPT_ID_VALID(eap->line2))
+	if (eap->addr_count > 0 && !SCRIPT_ID_VALID(eap->line2))
 	    emsg(_(e_invalid_argument));
 	else
 	{
-	    eap->arg = SCRIPT_ITEM(eap->line2)->sn_name;
+	    if (eap->addr_count > 0)
+		eap->arg = SCRIPT_ITEM(eap->line2)->sn_name;
+	    else
+	    {
+		expand_env(eap->arg, NameBuff, MAXPATHL);
+		eap->arg = NameBuff;
+	    }
 	    do_exedit(eap, NULL);
 	}
 	return;
diff --git a/src/testdir/test_cmdline.vim b/src/testdir/test_cmdline.vim
index 299210b..d337442 100644
--- a/src/testdir/test_cmdline.vim
+++ b/src/testdir/test_cmdline.vim
@@ -3257,4 +3257,31 @@
   call assert_equal("\"breakdel here ", @:)
 endfunc
 
+" Test for :scriptnames argument completion
+func Test_cmdline_complete_scriptnames()
+  set wildmenu
+  call writefile(['let a = 1'], 'Xa1b2c3.vim')
+  source Xa1b2c3.vim
+  call feedkeys(":script \<Tab>\<Left>\<Left>\<C-B>\"\<CR>", 'tx')
+  call assert_match("\"script .*Xa1b2c3.vim$", @:)
+  call feedkeys(":script    \<Tab>\<Left>\<Left>\<C-B>\"\<CR>", 'tx')
+  call assert_match("\"script .*Xa1b2c3.vim$", @:)
+  call feedkeys(":script b2c3\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"script b2c3", @:)
+  call feedkeys(":script 2\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_match("\"script 2\<Tab>$", @:)
+  call feedkeys(":script \<Tab>\<Left>\<Left> \<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_match("\"script .*Xa1b2c3.vim $", @:)
+  call feedkeys(":script \<Tab>\<Left>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"script ", @:)
+  call assert_match('Xa1b2c3.vim$', getcompletion('.*Xa1b2.*', 'scriptnames')[0])
+  call assert_equal([], getcompletion('Xa1b2', 'scriptnames'))
+  new
+  call feedkeys(":script \<Tab>\<Left>\<Left>\<CR>", 'tx')
+  call assert_equal('Xa1b2c3.vim', fnamemodify(@%, ':t'))
+  bw!
+  call delete('Xa1b2c3.vim')
+  set wildmenu&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_quickfix.vim b/src/testdir/test_quickfix.vim
index 42b8193..f5f385f 100644
--- a/src/testdir/test_quickfix.vim
+++ b/src/testdir/test_quickfix.vim
@@ -6202,4 +6202,39 @@
   %bw!
 endfunc
 
+" Test for the status message that is displayed when opening a new quickfix
+" list
+func Test_qflist_statusmsg()
+  cexpr "1\n2"
+  cexpr "1\n2\n3\ntest_quickfix.vim:1:msg"
+  call assert_equal('(4 of 4): msg', v:statusmsg)
+  call setqflist([], 'f')
+  %bw!
+
+  " When creating a new quickfix list, if an autocmd changes the quickfix list
+  " in the stack, then an error message should be displayed.
+  augroup QF_Test
+    au!
+    au BufEnter test_quickfix.vim colder
+  augroup END
+  cexpr "1\n2"
+  call assert_fails('cexpr "1\n2\n3\ntest_quickfix.vim:1:msg"', 'E925:')
+  call setqflist([], 'f')
+  augroup QF_Test
+    au!
+  augroup END
+  %bw!
+
+  augroup QF_Test
+    au!
+    au BufEnter test_quickfix.vim caddexpr "4"
+  augroup END
+  call assert_fails('cexpr "1\n2\n3\ntest_quickfix.vim:1:msg"', 'E925:')
+  call setqflist([], 'f')
+  augroup QF_Test
+    au!
+  augroup END
+  %bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/usercmd.c b/src/usercmd.c
index 40d951f..0e9d712 100644
--- a/src/usercmd.c
+++ b/src/usercmd.c
@@ -93,6 +93,7 @@
     {EXPAND_USER_VARS, "var"},
 #if defined(FEAT_EVAL)
     {EXPAND_BREAKPOINT, "breakpoint"},
+    {EXPAND_SCRIPTNAMES, "scriptnames"},
 #endif
     {0, NULL}
 };
diff --git a/src/version.c b/src/version.c
index ba16773..17d15c0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4617,
+/**/
     4616,
 /**/
     4615,
diff --git a/src/vim.h b/src/vim.h
index d7a2464..0a923f1 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -802,6 +802,7 @@
 #define EXPAND_DIFF_BUFFERS	49
 #define EXPAND_DISASSEMBLE	50
 #define EXPAND_BREAKPOINT	51
+#define EXPAND_SCRIPTNAMES	52
 
 // Values for exmode_active (0 is no exmode)
 #define EXMODE_NORMAL		1