vim-patch:9.0.0284: using static buffer for multiple completion functions

Problem:    Using static buffer for multiple completion functions.
Solution:   Use one buffer in expand_T.
5ff595d9db

src/nvim/cmdhist.c

@@ -90,14 +90,14 @@ static char *(history_names[]) = {
 /// arguments of the ":history command.
 char *get_history_arg(expand_T *xp, int idx)
 {
-  static char_u compl[2] = { NUL, NUL };
-  char *short_names = ":=@>?/";
-  int short_names_count = (int)STRLEN(short_names);
-  int history_name_count = ARRAY_SIZE(history_names) - 1;
+  const char *short_names = ":=@>?/";
+  const int short_names_count = (int)STRLEN(short_names);
+  const int history_name_count = ARRAY_SIZE(history_names) - 1;
 
   if (idx < short_names_count) {
-    compl[0] = (char_u)short_names[idx];
-    return (char *)compl;
+    xp->xp_buf[0] = short_names[idx];
+    xp->xp_buf[1] = NUL;
+    return xp->xp_buf;
   }
   if (idx < short_names_count + history_name_count) {
     return history_names[idx - short_names_count];

src/nvim/ex_cmds_defs.h

@@ -237,6 +237,8 @@ struct expand {
   int xp_col;                   // cursor position in line
   char **xp_files;              // list of files
   char *xp_line;                // text being completed
+#define EXPAND_BUF_LEN 256
+  char xp_buf[EXPAND_BUF_LEN];  // buffer for returned match
 };
 
 // values for xp_backslash

src/nvim/os/env.c

@@ -1156,15 +1156,12 @@ char *home_replace_save(buf_T *buf, const char *src)
 /// Function given to ExpandGeneric() to obtain an environment variable name.
 char *get_env_name(expand_T *xp, int idx)
 {
-#define ENVNAMELEN 100
-  // this static buffer is needed to avoid a memory leak in ExpandGeneric
-  static char_u name[ENVNAMELEN];
   assert(idx >= 0);
   char *envname = os_getenvname_at_index((size_t)idx);
   if (envname) {
-    STRLCPY(name, envname, ENVNAMELEN);
+    STRLCPY(xp->xp_buf, envname, EXPAND_BUF_LEN);
     xfree(envname);
-    return (char *)name;
+    return xp->xp_buf;
   }
   return NULL;
 }

src/nvim/syntax.c

@@ -5737,9 +5737,6 @@ void set_context_in_syntax_cmd(expand_T *xp, const char *arg)
  */
 char *get_syntax_name(expand_T *xp, int idx)
 {
-#define CBUFFER_LEN 256
-  static char cbuffer[CBUFFER_LEN]; // TODO: better solution
-
   switch (expand_what) {
   case EXP_SUBCMD:
     return subcommands[idx].name;
@@ -5761,9 +5758,9 @@ char *get_syntax_name(expand_T *xp, int idx)
   }
   case EXP_CLUSTER:
     if (idx < curwin->w_s->b_syn_clusters.ga_len) {
-      vim_snprintf(cbuffer, CBUFFER_LEN, "@%s",
+      vim_snprintf(xp->xp_buf, EXPAND_BUF_LEN, "@%s",
                    SYN_CLSTR(curwin->w_s)[idx].scl_name);
-      return cbuffer;
+      return xp->xp_buf;
     } else {
       return NULL;
     }