vim-patch:9.0.1007: there is no way to get a list of swap file names

Problem:    There is no way to get a list of swap file names.
Solution:   Add the swapfilelist() function.  Use it in the test script to
            clean up.  Remove deleting individual swap files.

https://github.com/vim/vim/commit/c216a7a21a25a701b84b79abc1ba6ab0baa3a311

vim-patch:9.0.1005: a failed test may leave a swap file behind

Problem:    A failed test may leave a swap file behind.
Solution:   Delete the swap file to avoid another test to fail.  Use another
            file name.

https://github.com/vim/vim/commit/d0f8d39d20f8d42f7451f781f7be0bcd20e06741

Cherry-pick test_window_cmd.vim changes from patch 8.2.1593.
Remove FUNC_ATTR_UNUSED from eval functions as fptr is always unused.

Co-authored-by: Bram Moolenaar <Bram@vim.org>

4 files changed, 32 insertions, 12 deletions

diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 7dbfac80f3..5babfa4809 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -400,6 +400,7 @@ return {
     strwidth={args=1, base=1, fast=true},
     submatch={args={1, 2}, base=1},
     substitute={args=4, base=1},
+    swapfilelist={},
     swapinfo={args=1, base=1},
     swapname={args=1, base=1},
     synID={args=3},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 28901d6e55..d9226214c6 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -44,6 +44,7 @@
 #include "nvim/eval/executor.h"
 #include "nvim/eval/funcs.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/typval_defs.h"
 #include "nvim/eval/userfunc.h"
 #include "nvim/eval/vars.h"
 #include "nvim/eval/window.h"
@@ -3850,8 +3851,7 @@ static void f_insert(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 }
 
 /// "interrupt()" function
-static void f_interrupt(typval_T *argvars FUNC_ATTR_UNUSED, typval_T *rettv FUNC_ATTR_UNUSED,
-                        EvalFuncData fptr FUNC_ATTR_UNUSED)
+static void f_interrupt(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
   got_int = true;
 }
@@ -8523,6 +8523,13 @@ static void f_substitute(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   }
 }
 
+/// "swapfilelist()" function
+static void f_swapfilelist(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  tv_list_alloc_ret(rettv, kListLenUnknown);
+  recover_names(NULL, false, rettv->vval.v_list, 0, NULL);
+}
+
 /// "swapinfo(swap_filename)" function
 static void f_swapinfo(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 698c2dcc4f..6ff26b6e96 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -466,7 +466,7 @@ int main(int argc, char **argv)
   // Recovery mode without a file name: List swap files.
   // Uses the 'dir' option, therefore it must be after the initializations.
   if (recoverymode && fname == NULL) {
-    recover_names(NULL, true, 0, NULL);
+    recover_names(NULL, true, NULL, 0, NULL);
     os_exit(0);
   }
 
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 0c38f18739..498b4b5960 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -762,7 +762,7 @@ void ml_recover(bool checkext)
     directly = false;
 
     // count the number of matching swap files
-    len = recover_names(fname, false, 0, NULL);
+    len = recover_names(fname, false, NULL, 0, NULL);
     if (len == 0) {                 // no swap files found
       semsg(_("E305: No swap file found for %s"), fname);
       goto theend;
@@ -772,7 +772,7 @@ void ml_recover(bool checkext)
       i = 1;
     } else {                          // several swap files found, choose
       // list the names of the swap files
-      (void)recover_names(fname, true, 0, NULL);
+      (void)recover_names(fname, true, NULL, 0, NULL);
       msg_putchar('\n');
       msg_puts(_("Enter number of swap file to use (0 to quit): "));
       i = get_number(false, NULL);
@@ -781,7 +781,7 @@ void ml_recover(bool checkext)
       }
     }
     // get the swap file name that will be used
-    (void)recover_names(fname, false, i, &fname_used);
+    (void)recover_names(fname, false, NULL, i, &fname_used);
   }
   if (fname_used == NULL) {
     goto theend;  // user chose invalid number.
@@ -1200,13 +1200,15 @@ theend:
 /// - list the swap files for "vim -r"
 /// - count the number of swap files when recovering
 /// - list the swap files when recovering
+/// - list the swap files for swapfilelist()
 /// - find the name of the n'th swap file when recovering
 ///
 /// @param fname  base for swap file name
-/// @param list  when true, list the swap file names
+/// @param do_list  when true, list the swap file names
+/// @param ret_list  when not NULL add file names to it
 /// @param nr  when non-zero, return nr'th swap file name
 /// @param fname_out  result when "nr" > 0
-int recover_names(char *fname, int list, int nr, char **fname_out)
+int recover_names(char *fname, bool do_list, list_T *ret_list, int nr, char **fname_out)
 {
   int num_names;
   char *(names[6]);
@@ -1230,7 +1232,7 @@ int recover_names(char *fname, int list, int nr, char **fname_out)
     fname_res = fname;
   }
 
-  if (list) {
+  if (do_list) {
     // use msg() to start the scrolling properly
     msg(_("Swap files found:"));
     msg_putchar('\n');
@@ -1306,9 +1308,11 @@ int recover_names(char *fname, int list, int nr, char **fname_out)
       }
     }
 
-    // remove swapfile name of the current buffer, it must be ignored
+    // Remove swapfile name of the current buffer, it must be ignored.
+    // But keep it for swapfilelist().
     if (curbuf->b_ml.ml_mfp != NULL
-        && (p = curbuf->b_ml.ml_mfp->mf_fname) != NULL) {
+        && (p = curbuf->b_ml.ml_mfp->mf_fname) != NULL
+        && ret_list == NULL) {
       for (int i = 0; i < num_files; i++) {
         // Do not expand wildcards, on Windows would try to expand
         // "%tmp%" in "%tmp%file"
@@ -1333,7 +1337,7 @@ int recover_names(char *fname, int list, int nr, char **fname_out)
         *fname_out = xstrdup(files[nr - 1 + num_files - file_count]);
         dirp = "";                        // stop searching
       }
-    } else if (list) {
+    } else if (do_list) {
       if (dir_name[0] == '.' && dir_name[1] == NUL) {
         if (fname == NULL) {
           msg_puts(_("   In current directory:\n"));
@@ -1359,6 +1363,14 @@ int recover_names(char *fname, int list, int nr, char **fname_out)
         msg_puts(_("      -- none --\n"));
       }
       ui_flush();
+    } else if (ret_list != NULL) {
+      for (int i = 0; i < num_files; i++) {
+        char *name = concat_fnames(dir_name, files[i], true);
+        if (name != NULL) {
+          tv_list_append_string(ret_list, name, -1);
+          xfree(name);
+        }
+      }
     } else {
       file_count += num_files;
     }