refactor: fix clang and PVS warnings (#19532)

src/nvim/eval/vars.c

@@ -514,6 +514,7 @@ static const char *list_arg_vars(exarg_T *eap, const char *arg, int *first)
               const char *const used_name = (arg == arg_subsc
                                              ? name
                                              : name_start);
+              assert(used_name != NULL);
               const ptrdiff_t name_size = (used_name == tofree
                                            ? (ptrdiff_t)strlen(used_name)
                                            : (arg - used_name));

src/nvim/ex_docmd.c

@@ -3052,6 +3052,7 @@ char *find_ex_command(exarg_T *eap, int *full)
     } else {
       eap->cmdidx = CMD_bang;
     }
+    assert(eap->cmdidx >= 0);
 
     for (; (int)eap->cmdidx < CMD_SIZE;
          eap->cmdidx = (cmdidx_T)((int)eap->cmdidx + 1)) {

src/nvim/ex_getln.c

@@ -3336,7 +3336,7 @@ static void ui_ext_cmdline_show(CmdlineInfo *line)
 {
   Arena arena = ARENA_EMPTY;
   arena_start(&arena, &ui_ext_fixblk);
-  Array content = ARRAY_DICT_INIT;
+  Array content;
   if (cmdline_star) {
     content = arena_array(&arena, 1);
     size_t len = 0;

src/nvim/highlight_group.c

@@ -956,8 +956,8 @@ void do_highlight(const char *line, const bool forceit, const bool init)
         linep++;
       }
       size_t key_len = (size_t)(linep - key_start);
-      if (key_len > sizeof key - 1) {
-        semsg(_("E423: Illegal argument"));
+      if (key_len > sizeof(key) - 1) {
+        emsg(_("E423: Illegal argument"));
         error = true;
         break;
       }
@@ -1004,8 +1004,8 @@ void do_highlight(const char *line, const bool forceit, const bool init)
         break;
       }
       size_t arg_len = (size_t)(linep - arg_start);
-      if (arg_len > sizeof arg - 1) {
-        semsg(_("E423: Illegal argument"));
+      if (arg_len > sizeof(arg) - 1) {
+        emsg(_("E423: Illegal argument"));
         error = true;
         break;
       }

src/nvim/log.c

@@ -310,7 +310,7 @@ static bool v_do_log_to_file(FILE *log_file, int log_level, const char *context,
     const char *parent = path_tail(os_getenv(ENV_NVIM));
     // Servername. Empty until starting=false.
     const char *serv = path_tail(get_vim_var_str(VV_SEND_SERVER));
-    if (parent && parent[0] != NUL) {
+    if (parent[0] != NUL) {
       snprintf(name, sizeof(name), "%s/c", parent);  // "/c" indicates child.
     } else if (serv[0] != NUL) {
       snprintf(name, sizeof(name), "%s", serv);

src/nvim/mark.c

@@ -491,7 +491,7 @@ fmark_T *mark_get_visual(buf_T *buf, int name)
       mark = pos_to_mark(buf, NULL, endp);
     }
 
-    if (mark != NULL && buf->b_visual.vi_mode == 'V') {
+    if (buf->b_visual.vi_mode == 'V') {
       if (name == '<') {
         mark->mark.col = 0;
       } else {

src/nvim/msgpack_rpc/unpacker.c

@@ -425,8 +425,8 @@ redo:
       arena_start(&p->arena, &p->reuse_blk);
       p->grid_line_event = arena_alloc(&p->arena, sizeof *p->grid_line_event, true);
       g = p->grid_line_event;
-      FALLTHROUGH;
     }
+    FALLTHROUGH;
 
   case 13:
     NEXT_TYPE(tok, MPACK_TOKEN_ARRAY);

src/nvim/normal.c

@@ -5102,6 +5102,7 @@ static void nv_brackets(cmdarg_T *cap)
   } else if (cap->nchar == '\'' || cap->nchar == '`') {
     // "['", "[`", "]'" and "]`": jump to next mark
     fmark_T *fm = pos_to_mark(curbuf, NULL, curwin->w_cursor);
+    assert(fm != NULL);
     fmark_T *prev_fm;
     for (n = cap->count1; n > 0; n--) {
       prev_fm = fm;

src/nvim/screen.c

@@ -2119,7 +2119,7 @@ static int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool noc
   bool has_decor = false;               // this buffer has decoration
   int win_col_offset = 0;               // offset for window columns
 
-  char_u buf_fold[FOLD_TEXT_LEN + 1];   // Hold value returned by get_foldtext
+  char_u buf_fold[FOLD_TEXT_LEN];       // Hold value returned by get_foldtext
 
   bool area_active = false;