vim-patch:8.2.3530: ":buf \{a}" fails while ":edit \{a}" works

Problem:    ":buf \{a}" fails while ":edit \{a}" works.
Solution:   Unescape "\{". (closes vim/vim#8917)
21c1a0c2f1

src/nvim/eval/funcs.c

@@ -2467,7 +2467,7 @@ static void f_fmod(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 /// "fnameescape({string})" function
 static void f_fnameescape(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  rettv->vval.v_string = vim_strsave_fnameescape(tv_get_string(&argvars[0]), false);
+  rettv->vval.v_string = vim_strsave_fnameescape(tv_get_string(&argvars[0]), VSE_NONE);
   rettv->v_type = VAR_STRING;
 }
 

src/nvim/ex_getln.c

@@ -4334,6 +4334,7 @@ void ExpandEscape(expand_T *xp, char_u *str, int numfiles, char_u **files, int o
 {
   int i;
   char_u *p;
+  const int vse_what = xp->xp_context == EXPAND_BUFFERS ? VSE_BUFFER : VSE_NONE;
 
   /*
    * May change home directory back to "~"
@@ -4365,10 +4366,10 @@ void ExpandEscape(expand_T *xp, char_u *str, int numfiles, char_u **files, int o
 #endif
         }
 #ifdef BACKSLASH_IN_FILENAME
-        p = (char_u *)vim_strsave_fnameescape((const char *)files[i], false);
+        p = (char_u *)vim_strsave_fnameescape((const char *)files[i], vse_what);
 #else
         p = (char_u *)vim_strsave_fnameescape((const char *)files[i],
-                                              xp->xp_shell);
+                                              xp->xp_shell ? VSE_SHELL : vse_what);
 #endif
         xfree(files[i]);
         files[i] = p;
@@ -4400,25 +4401,30 @@ void ExpandEscape(expand_T *xp, char_u *str, int numfiles, char_u **files, int o
   }
 }
 
-/// Escape special characters in a file name for use as a command argument
+/// Escape special characters in "fname", depending on "what":
 ///
 /// @param[in]  fname  File name to escape.
-/// @param[in]  shell  What to escape for: if false, escapes for VimL command,
+/// @param[in]  what   What to escape for:
-///                    if true then it escapes for a shell command.
+/// - VSE_NONE: for when used as a file name argument after a Vim command.
+/// - VSE_SHELL: for a shell command.
+/// - VSE_BUFFER: for the ":buffer" command.
 ///
 /// @return [allocated] escaped file name.
-char *vim_strsave_fnameescape(const char *const fname, const bool shell FUNC_ATTR_UNUSED)
+char *vim_strsave_fnameescape(const char *const fname, const int what)
   FUNC_ATTR_NONNULL_RET FUNC_ATTR_MALLOC FUNC_ATTR_NONNULL_ALL
 {
 #ifdef BACKSLASH_IN_FILENAME
 # define PATH_ESC_CHARS " \t\n*?[{`%#'\"|!<"
+# define BUFFER_ESC_CHARS ((char_u *)" \t\n*?[`%#'\"|!<")
   char_u buf[sizeof(PATH_ESC_CHARS)];
   int j = 0;
 
-  // Don't escape '[', '{' and '!' if they are in 'isfname'.
+  // Don't escape '[', '{' and '!' if they are in 'isfname' and for the
-  for (const char *s = PATH_ESC_CHARS; *s != NUL; s++) {
+  // ":buffer" command.
-    if ((*s != '[' && *s != '{' && *s != '!') || !vim_isfilec(*s)) {
+  for (const char *p = what == VSE_BUFFER ? BUFFER_ESC_CHARS : PATH_ESC_CHARS;
-      buf[j++] = *s;
+       *p != NUL; p++) {
+    if ((*p != '[' && *p != '{' && *p != '!') || !vim_isfilec(*p)) {
+      buf[j++] = *p;
     }
   }
   buf[j] = NUL;
@@ -4427,9 +4433,12 @@ char *vim_strsave_fnameescape(const char *const fname, const bool shell FUNC_ATT
 #else
 # define PATH_ESC_CHARS ((char_u *)" \t\n*?[{`$\\%#'\"|!<")
 # define SHELL_ESC_CHARS ((char_u *)" \t\n*?[{`$\\%#'\"|!<>();&")
+# define BUFFER_ESC_CHARS ((char_u *)" \t\n*?[`$\\%#'\"|!<")
   char *p =
-    (char *)vim_strsave_escaped((const char_u *)fname, (shell ? SHELL_ESC_CHARS : PATH_ESC_CHARS));
+    (char *)vim_strsave_escaped((const char_u *)fname,
-  if (shell && csh_like_shell()) {
+                                what == VSE_SHELL ? SHELL_ESC_CHARS
+                                : what == VSE_BUFFER ? BUFFER_ESC_CHARS : PATH_ESC_CHARS);
+  if (what == VSE_SHELL && csh_like_shell()) {
     // For csh and similar shells need to put two backslashes before '!'.
     // One is taken by Vim, one by the shell.
     char *s = (char *)vim_strsave_escaped((const char_u *)p,

src/nvim/ex_getln.h

@@ -34,6 +34,11 @@
 #define WILD_BUFLASTUSED        0x1000
 #define BUF_DIFF_FILTER         0x2000
 
+// flags used by vim_strsave_fnameescape()
+#define VSE_NONE        0
+#define VSE_SHELL       1       ///< escape for a shell command
+#define VSE_BUFFER      2       ///< escape for a ":buffer" command
+
 /// Present history tables
 typedef enum {
   HIST_DEFAULT = -2,  ///< Default (current) history.

src/nvim/ex_session.c

@@ -285,7 +285,7 @@ static char *ses_escape_fname(char *name, unsigned *flagp)
   }
 
   // Escape special characters.
-  p = vim_strsave_fnameescape(sname, false);
+  p = vim_strsave_fnameescape(sname, VSE_NONE);
   xfree(sname);
   return p;
 }

src/nvim/normal.c

@@ -4321,7 +4321,7 @@ static void nv_ident(cmdarg_T *cap)
     ptr = vim_strnsave(ptr, n);
     if (kp_ex) {
       // Escape the argument properly for an Ex command
-      p = (char_u *)vim_strsave_fnameescape((const char *)ptr, false);
+      p = (char_u *)vim_strsave_fnameescape((const char *)ptr, VSE_NONE);
     } else {
       // Escape the argument properly for a shell command
       p = vim_strsave_shellescape(ptr, true, true);

src/nvim/testdir/test_cmdline.vim

@@ -900,6 +900,12 @@ func Test_cmdline_complete_various()
   call feedkeys(":unlet one two\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"unlet one two", @:)
 
+  " completion for the :buffer command with curlies
+  edit \{someFile}
+  call feedkeys(":buf someFile\<C-A>\<C-B>\"\<CR>", 'xt')
+  call assert_equal("\"buf {someFile}", @:)
+  bwipe {someFile}
+
   " completion for the :bdelete command
   call feedkeys(":bdel a b c\<C-A>\<C-B>\"\<CR>", 'xt')
   call assert_equal("\"bdel a b c", @:)