eval: Move remaining get_tv_string* functions to eval/typval.c

23 files changed, 1142 insertions, 1037 deletions

diff --git a/src/nvim/ascii.h b/src/nvim/ascii.h
index 31851a84e6..37b83efb61 100644
--- a/src/nvim/ascii.h
+++ b/src/nvim/ascii.h
@@ -20,15 +20,13 @@
 #define BS              '\010'
 #define TAB             '\011'
 #define NL              '\012'
-#define NL_STR          (char_u *)"\012"
+#define NL_STR          "\012"
 #define FF              '\014'
 #define CAR             '\015'  /* CR is used by Mac OS X */
 #define ESC             '\033'
-#define ESC_STR         (char_u *)"\033"
-#define ESC_STR_nc      "\033"
+#define ESC_STR         "\033"
 #define DEL             0x7f
-#define DEL_STR         (char_u *)"\177"
-#define CSI             0x9b    /* Control Sequence Introducer */
+#define CSI             0x9b    // Control Sequence Introducer
 #define CSI_STR         "\233"
 #define DCS             0x90    /* Device Control String */
 #define STERM           0x9c    /* String Terminator */
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index cb6a9fa43c..6c22108853 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -90,7 +90,6 @@ int buf_init_chartab(buf_T *buf, int global)
 {
   int c;
   int c2;
-  char_u *p;
   int i;
   bool tilde;
   bool do_isalpha;
@@ -144,7 +143,8 @@ int buf_init_chartab(buf_T *buf, int global)
   // Walk through the 'isident', 'iskeyword', 'isfname' and 'isprint'
   // options Each option is a list of characters, character numbers or
   // ranges, separated by commas, e.g.: "200-210,x,#-178,-"
-  for (i = global ? 0 : 3; i <= 3; ++i) {
+  for (i = global ? 0 : 3; i <= 3; i++) {
+    const char_u *p;
     if (i == 0) {
       // first round: 'isident'
       p = p_isi;
@@ -169,7 +169,7 @@ int buf_init_chartab(buf_T *buf, int global)
       }
 
       if (ascii_isdigit(*p)) {
-        c = getdigits_int(&p);
+        c = getdigits_int((char_u **)&p);
       } else {
         c = mb_ptr2char_adv(&p);
       }
@@ -179,7 +179,7 @@ int buf_init_chartab(buf_T *buf, int global)
         ++p;
 
         if (ascii_isdigit(*p)) {
-          c2 = getdigits_int(&p);
+          c2 = getdigits_int((char_u **)&p);
         } else {
           c2 = mb_ptr2char_adv(&p);
         }
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index b396251051..da09aed3dc 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1423,7 +1423,7 @@ static void ins_ctrl_v(void)
     edit_putchar('^', TRUE);
     did_putchar = TRUE;
   }
-  AppendToRedobuff((char_u *)CTRL_V_STR);       /* CTRL-V */
+  AppendToRedobuff(CTRL_V_STR);
 
   add_to_showcmd_c(Ctrl_V);
 
@@ -1977,7 +1977,6 @@ static bool ins_compl_accept_char(int c)
  */
 int ins_compl_add_infercase(char_u *str, int len, int icase, char_u *fname, int dir, int flags)
 {
-  char_u      *p;
   int i, c;
   int actual_len;                       /* Take multi-byte characters */
   int actual_compl_length;              /* into account. */
@@ -1987,11 +1986,11 @@ int ins_compl_add_infercase(char_u *str, int len, int icase, char_u *fname, int
   int was_letter = FALSE;
 
   if (p_ic && curbuf->b_p_inf && len > 0) {
-    /* Infer case of completed part. */
+    // Infer case of completed part.
 
-    /* Find actual length of completion. */
+    // Find actual length of completion.
     if (has_mbyte) {
-      p = str;
+      const char_u *p = str;
       actual_len = 0;
       while (*p != NUL) {
         mb_ptr_adv(p);
@@ -2002,7 +2001,7 @@ int ins_compl_add_infercase(char_u *str, int len, int icase, char_u *fname, int
 
     /* Find actual length of original text. */
     if (has_mbyte) {
-      p = compl_orig_text;
+      const char_u *p = compl_orig_text;
       actual_compl_length = 0;
       while (*p != NUL) {
         mb_ptr_adv(p);
@@ -2018,27 +2017,35 @@ int ins_compl_add_infercase(char_u *str, int len, int icase, char_u *fname, int
 
     /* Allocate wide character array for the completion and fill it. */
     wca = xmalloc(actual_len * sizeof(*wca));
-    p = str;
-    for (i = 0; i < actual_len; ++i)
-      if (has_mbyte)
-        wca[i] = mb_ptr2char_adv(&p);
-      else
-        wca[i] = *(p++);
+    {
+      const char_u *p = str;
+      for (i = 0; i < actual_len; i++) {
+        if (has_mbyte) {
+          wca[i] = mb_ptr2char_adv(&p);
+        } else {
+          wca[i] = *(p++);
+        }
+      }
+    }
 
-    /* Rule 1: Were any chars converted to lower? */
-    p = compl_orig_text;
-    for (i = 0; i < min_len; ++i) {
-      if (has_mbyte)
-        c = mb_ptr2char_adv(&p);
-      else
-        c = *(p++);
-      if (vim_islower(c)) {
-        has_lower = TRUE;
-        if (vim_isupper(wca[i])) {
-          /* Rule 1 is satisfied. */
-          for (i = actual_compl_length; i < actual_len; ++i)
-            wca[i] = vim_tolower(wca[i]);
-          break;
+    // Rule 1: Were any chars converted to lower?
+    {
+      const char_u *p = compl_orig_text;
+      for (i = 0; i < min_len; i++) {
+        if (has_mbyte) {
+          c = mb_ptr2char_adv(&p);
+        } else {
+          c = *(p++);
+        }
+        if (vim_islower(c)) {
+          has_lower = true;
+          if (vim_isupper(wca[i])) {
+            // Rule 1 is satisfied.
+            for (i = actual_compl_length; i < actual_len; i++) {
+              wca[i] = vim_tolower(wca[i]);
+            }
+            break;
+          }
         }
       }
     }
@@ -2048,49 +2055,57 @@ int ins_compl_add_infercase(char_u *str, int len, int icase, char_u *fname, int
      * upper case.
      */
     if (!has_lower) {
-      p = compl_orig_text;
-      for (i = 0; i < min_len; ++i) {
-        if (has_mbyte)
+      const char_u *p = compl_orig_text;
+      for (i = 0; i < min_len; i++) {
+        if (has_mbyte) {
           c = mb_ptr2char_adv(&p);
-        else
+        } else {
           c = *(p++);
+        }
         if (was_letter && vim_isupper(c) && vim_islower(wca[i])) {
-          /* Rule 2 is satisfied. */
-          for (i = actual_compl_length; i < actual_len; ++i)
+          // Rule 2 is satisfied.
+          for (i = actual_compl_length; i < actual_len; i++) {
             wca[i] = vim_toupper(wca[i]);
+          }
           break;
         }
         was_letter = vim_islower(c) || vim_isupper(c);
       }
     }
 
-    /* Copy the original case of the part we typed. */
-    p = compl_orig_text;
-    for (i = 0; i < min_len; ++i) {
-      if (has_mbyte)
-        c = mb_ptr2char_adv(&p);
-      else
-        c = *(p++);
-      if (vim_islower(c))
-        wca[i] = vim_tolower(wca[i]);
-      else if (vim_isupper(c))
-        wca[i] = vim_toupper(wca[i]);
+    // Copy the original case of the part we typed.
+    {
+      const char_u *p = compl_orig_text;
+      for (i = 0; i < min_len; i++) {
+        if (has_mbyte) {
+          c = mb_ptr2char_adv(&p);
+        } else {
+          c = *(p++);
+        }
+        if (vim_islower(c)) {
+          wca[i] = vim_tolower(wca[i]);
+        } else if (vim_isupper(c)) {
+          wca[i] = vim_toupper(wca[i]);
+        }
+      }
     }
 
-    /*
-     * Generate encoding specific output from wide character array.
-     * Multi-byte characters can occupy up to five bytes more than
-     * ASCII characters, and we also need one byte for NUL, so stay
-     * six bytes away from the edge of IObuff.
-     */
-    p = IObuff;
-    i = 0;
-    while (i < actual_len && (p - IObuff + 6) < IOSIZE)
-      if (has_mbyte)
-        p += (*mb_char2bytes)(wca[i++], p);
-      else
-        *(p++) = wca[i++];
-    *p = NUL;
+    // Generate encoding specific output from wide character array.
+    // Multi-byte characters can occupy up to five bytes more than
+    // ASCII characters, and we also need one byte for NUL, so stay
+    // six bytes away from the edge of IObuff.
+    {
+      char_u *p = IObuff;
+      i = 0;
+      while (i < actual_len && (p - IObuff + 6) < IOSIZE) {
+        if (has_mbyte) {
+          p += (*mb_char2bytes)(wca[i++], p);
+        } else {
+          *(p++) = wca[i++];
+        }
+      }
+      *p = NUL;
+    }
 
     xfree(wca);
 
@@ -3594,7 +3609,7 @@ int ins_compl_add_tv(typval_T *const tv, const Direction dir)
     adup = (bool)tv_dict_get_number(tv->vval.v_dict, "dup");
     aempty = (bool)tv_dict_get_number(tv->vval.v_dict, "empty");
   } else {
-    word = (const char *)get_tv_string_chk(tv);
+    word = (const char *)tv_get_string_chk(tv);
     memset(cptext, 0, sizeof(cptext));
   }
   if (word == NULL || (!aempty && *word == NUL)) {
@@ -5785,15 +5800,16 @@ comp_textwidth (
  */
 static void redo_literal(int c)
 {
-  char_u buf[10];
+  char buf[10];
 
-  /* Only digits need special treatment.  Translate them into a string of
-   * three digits. */
+  // Only digits need special treatment.  Translate them into a string of
+  // three digits.
   if (ascii_isdigit(c)) {
-    vim_snprintf((char *)buf, sizeof(buf), "%03d", c);
+    vim_snprintf(buf, sizeof(buf), "%03d", c);
     AppendToRedobuff(buf);
-  } else
+  } else {
     AppendCharToRedobuff(c);
+  }
 }
 
 // start_arrow() is called when an arrow key is used in insert mode.
@@ -5822,8 +5838,8 @@ static void start_arrow_common(pos_T *end_insert_pos, bool end_change)
 {
   if (!arrow_used && end_change) {  // something has been inserted
     AppendToRedobuff(ESC_STR);
-    stop_insert(end_insert_pos, FALSE, FALSE);
-    arrow_used = TRUE;          /* this means we stopped the current insert */
+    stop_insert(end_insert_pos, false, false);
+    arrow_used = true;  // This means we stopped the current insert.
   }
   check_spell_redraw();
 }
@@ -5880,7 +5896,7 @@ int stop_arrow(void)
       vr_lines_changed = 1;
     }
     ResetRedobuff();
-    AppendToRedobuff((char_u *)"1i");       /* pretend we start an insertion */
+    AppendToRedobuff("1i");  // Pretend we start an insertion.
     new_insert_skip = 2;
   } else if (ins_need_undo) {
     if (u_save_cursor() == OK)
@@ -6345,12 +6361,13 @@ stuff_inserted (
   }
 
   do {
-    stuffReadbuff(ptr);
-    /* a trailing "0" is inserted as "<C-V>048", "^" as "<C-V>^" */
-    if (last)
-      stuffReadbuff((char_u *)(last == '0'
-                               ? "\026\060\064\070"
-                               : "\026^"));
+    stuffReadbuff((const char *)ptr);
+    // A trailing "0" is inserted as "<C-V>048", "^" as "<C-V>^".
+    if (last) {
+      stuffReadbuff((last == '0'
+                     ? "\026\060\064\070"
+                     : "\026^"));
+    }
   } while (--count > 0);
 
   if (last)
@@ -7143,13 +7160,12 @@ static bool ins_esc(long *count, int cmdchar, bool nomove)
     disabled_redraw = false;
   }
   if (!arrow_used) {
-    /*
-     * Don't append the ESC for "r<CR>" and "grx".
-     * When 'insertmode' is set only CTRL-L stops Insert mode.  Needed for
-     * when "count" is non-zero.
-     */
-    if (cmdchar != 'r' && cmdchar != 'v')
-      AppendToRedobuff(p_im ? (char_u *)"\014" : ESC_STR);
+    // Don't append the ESC for "r<CR>" and "grx".
+    // When 'insertmode' is set only CTRL-L stops Insert mode.  Needed for
+    // when "count" is non-zero.
+    if (cmdchar != 'r' && cmdchar != 'v') {
+      AppendToRedobuff(p_im ? "\014" : ESC_STR);
+    }
 
     /*
      * Repeating insert may take a long time.  Check for
@@ -7303,7 +7319,8 @@ static bool ins_start_select(int c)
     // Execute the key in (insert) Select mode.
     stuffcharReadbuff(Ctrl_O);
     if (mod_mask) {
-      char_u buf[4] = { K_SPECIAL, KS_MODIFIER, mod_mask, NUL };
+      const char buf[] = { (char)K_SPECIAL, (char)KS_MODIFIER,
+                           (char)(uint8_t)mod_mask, NUL };
       stuffReadbuff(buf);
     }
     stuffcharReadbuff(c);
@@ -8111,11 +8128,11 @@ static bool ins_tab(void)
     return true;
   }
 
-  did_ai = FALSE;
-  did_si = FALSE;
-  can_si = FALSE;
-  can_si_back = FALSE;
-  AppendToRedobuff((char_u *)"\t");
+  did_ai = false;
+  did_si = false;
+  can_si = false;
+  can_si_back = false;
+  AppendToRedobuff("\t");
 
   if (p_sta && ind) {  // insert tab in indent, use "shiftwidth"
     temp = get_sw_value(curbuf);
@@ -8380,8 +8397,8 @@ static int ins_digraph(void)
       edit_unputchar();
     }
     if (cc != ESC) {
-      AppendToRedobuff((char_u *)CTRL_V_STR);
-      c = getdigraph(c, cc, TRUE);
+      AppendToRedobuff(CTRL_V_STR);
+      c = getdigraph(c, cc, true);
       clear_showcmd();
       return c;
     }
@@ -8443,12 +8460,13 @@ static int ins_ctrl_ey(int tc)
     if (c != NUL) {
       long tw_save;
 
-      /* The character must be taken literally, insert like it
-       * was typed after a CTRL-V, and pretend 'textwidth'
-       * wasn't set.  Digits, 'o' and 'x' are special after a
-       * CTRL-V, don't use it for these. */
-      if (c < 256 && !isalnum(c))
-        AppendToRedobuff((char_u *)CTRL_V_STR);         /* CTRL-V */
+      // The character must be taken literally, insert like it
+      // was typed after a CTRL-V, and pretend 'textwidth'
+      // wasn't set.  Digits, 'o' and 'x' are special after a
+      // CTRL-V, don't use it for these.
+      if (c < 256 && !isalnum(c)) {
+        AppendToRedobuff(CTRL_V_STR);
+      }
       tw_save = curbuf->b_p_tw;
       curbuf->b_p_tw = -1;
       insert_special(c, TRUE, FALSE);
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 65bb90fc15..3a0075e48a 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -173,7 +173,6 @@ static char *e_funcref = N_("E718: Funcref required");
 static char *e_dictrange = N_("E719: Cannot use [:] with a Dictionary");
 static char *e_nofunc = N_("E130: Unknown function: %s");
 static char *e_illvar = N_("E461: Illegal variable name: %s");
-static char *e_float_as_string = N_("E806: using Float as a String");
 static const char *e_readonlyvar = N_(
     "E46: Cannot change read-only variable \"%.*s\"");
 
@@ -1852,7 +1851,6 @@ static char_u *ex_let_one(char_u *arg, typval_T *const tv,
                           const char_u *const op)
   FUNC_ATTR_NONNULL_ARG(1, 2) FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  char_u *name;
   char_u *arg_end = NULL;
   int len;
   int opt_flags;
@@ -1864,7 +1862,7 @@ static char_u *ex_let_one(char_u *arg, typval_T *const tv,
   if (*arg == '$') {
     // Find the end of the name.
     arg++;
-    name = arg;
+    char *name = (char *)arg;
     len = get_env_len((const char_u **)&arg);
     if (len == 0) {
       EMSG2(_(e_invarg2), name - 1);
@@ -1875,26 +1873,28 @@ static char_u *ex_let_one(char_u *arg, typval_T *const tv,
                  && vim_strchr(endchars, *skipwhite(arg)) == NULL) {
         EMSG(_(e_letunexp));
       } else if (!check_secure()) {
-        const char_u c1 = name[len];
+        const char c1 = name[len];
         name[len] = NUL;
-        char_u *p = get_tv_string_chk(tv);
+        const char *p = tv_get_string_chk(tv);
         if (p != NULL && op != NULL && *op == '.') {
-          char *s = vim_getenv((char *)name);
+          char *s = vim_getenv(name);
 
           if (s != NULL) {
-            p = tofree = concat_str((char_u *)s, p);
+            tofree = concat_str((const char_u *)s, (const char_u *)p);
+            p = (const char *)tofree;
             xfree(s);
           }
         }
         if (p != NULL) {
-          vim_setenv((char *)name, (char *)p);
-          if (STRICMP(name, "HOME") == 0)
+          vim_setenv(name, p);
+          if (STRICMP(name, "HOME") == 0) {
             init_homedir();
-          else if (didset_vim && STRICMP(name, "VIM") == 0)
-            didset_vim = FALSE;
-          else if (didset_vimruntime
-                   && STRICMP(name, "VIMRUNTIME") == 0)
-            didset_vimruntime = FALSE;
+          } else if (didset_vim && STRICMP(name, "VIM") == 0) {
+            didset_vim = false;
+          } else if (didset_vimruntime
+                     && STRICMP(name, "VIMRUNTIME") == 0) {
+            didset_vimruntime = false;
+          }
           arg_end = arg;
         }
         name[len] = c1;
@@ -1914,16 +1914,16 @@ static char_u *ex_let_one(char_u *arg, typval_T *const tv,
     } else {
       int opt_type;
       long numval;
-      char_u *stringval = NULL;
-      char_u *s;
+      char *stringval = NULL;
 
       const char c1 = *p;
       *p = NUL;
 
       varnumber_T n = tv_get_number(tv);
-      s = get_tv_string_chk(tv);  // != NULL if number or string.
+      const char *s = tv_get_string_chk(tv);  // != NULL if number or string.
       if (s != NULL && op != NULL && *op != '=') {
-        opt_type = get_option_value(arg, &numval, &stringval, opt_flags);
+        opt_type = get_option_value(arg, &numval, (char_u **)&stringval,
+                                    opt_flags);
         if ((opt_type == 1 && *op == '.')
             || (opt_type == 0 && *op != '.')) {
           EMSG2(_(e_letwrong), op);
@@ -1935,44 +1935,45 @@ static char_u *ex_let_one(char_u *arg, typval_T *const tv,
               n = numval - n;
             }
           } else if (opt_type == 0 && stringval != NULL) {  // string
-            s = concat_str(stringval, s);
-            xfree(stringval);
-            stringval = s;
+            char *const oldstringval = stringval;
+            stringval = (char *)concat_str((const char_u *)stringval,
+                                           (const char_u *)s);
+            xfree(oldstringval);
+            s = stringval;
           }
         }
       }
       if (s != NULL) {
-        set_option_value((const char *)arg, n, (char *)s, opt_flags);
+        set_option_value((const char *)arg, n, s, opt_flags);
         arg_end = (char_u *)p;
       }
       *p = c1;
       xfree(stringval);
     }
-  }
-  /*
-   * ":let @r = expr": Set register contents.
-   */
-  else if (*arg == '@') {
-    ++arg;
-    if (op != NULL && (*op == '+' || *op == '-'))
-      EMSG2(_(e_letwrong), op);
-    else if (endchars != NULL
-             && vim_strchr(endchars, *skipwhite(arg + 1)) == NULL)
-      EMSG(_(e_letunexp));
-    else {
-      char_u      *ptofree = NULL;
+  // ":let @r = expr": Set register contents.
+  } else if (*arg == '@') {
+    arg++;
+    if (op != NULL && (*op == '+' || *op == '-')) {
+      emsgf(_(e_letwrong), op);
+    } else if (endchars != NULL
+               && vim_strchr(endchars, *skipwhite(arg + 1)) == NULL) {
+      emsgf(_(e_letunexp));
+    } else {
       char_u      *s;
 
-      char_u *p = get_tv_string_chk(tv);
+      char_u *ptofree = NULL;
+      const char *p = tv_get_string_chk(tv);
       if (p != NULL && op != NULL && *op == '.') {
         s = get_reg_contents(*arg == '@' ? '"' : *arg, kGRegExprSrc);
         if (s != NULL) {
-          p = ptofree = concat_str(s, p);
+          ptofree = concat_str(s, (const char_u *)p);
+          p = (const char *)ptofree;
           xfree(s);
         }
       }
       if (p != NULL) {
-        write_reg_contents(*arg == '@' ? '"' : *arg, p, STRLEN(p), false);
+        write_reg_contents(*arg == '@' ? '"' : *arg,
+                           (const char_u *)p, STRLEN(p), false);
         arg_end = arg + 1;
       }
       xfree(ptofree);
@@ -2129,13 +2130,14 @@ static char_u *get_lval(char_u *const name, typval_T *const rettv,
     } else {
       /* Get the index [expr] or the first index [expr: ]. */
       p = skipwhite(p + 1);
-      if (*p == ':')
-        empty1 = TRUE;
-      else {
-        empty1 = FALSE;
-        if (eval1(&p, &var1, TRUE) == FAIL)             /* recursive! */
+      if (*p == ':') {
+        empty1 = true;
+      } else {
+        empty1 = false;
+        if (eval1(&p, &var1, true) == FAIL) {  // Recursive!
           return NULL;
-        if (get_tv_string_chk(&var1) == NULL) {
+        }
+        if (!tv_check_str(&var1)) {
           // Not a number or string.
           tv_clear(&var1);
           return NULL;
@@ -2174,7 +2176,7 @@ static char_u *get_lval(char_u *const name, typval_T *const rettv,
             }
             return NULL;
           }
-          if (get_tv_string_chk(&var2) == NULL) {
+          if (!tv_check_str(&var2)) {
             // Not a number or string.
             if (!empty1) {
               tv_clear(&var1);
@@ -3810,16 +3812,15 @@ static int eval5(char_u **arg, typval_T *rettv, int evaluate)
       break;
 
     if ((op != '+' || rettv->v_type != VAR_LIST)
-        && (op == '.' || rettv->v_type != VAR_FLOAT)
-        ) {
-      /* For "list + ...", an illegal use of the first operand as
-       * a number cannot be determined before evaluating the 2nd
-       * operand: if this is also a list, all is ok.
-       * For "something . ...", "something - ..." or "non-list + ...",
-       * we know that the first operand needs to be a string or number
-       * without evaluating the 2nd operand.  So check before to avoid
-       * side effects after an error. */
-      if (evaluate && get_tv_string_chk(rettv) == NULL) {
+        && (op == '.' || rettv->v_type != VAR_FLOAT)) {
+      // For "list + ...", an illegal use of the first operand as
+      // a number cannot be determined before evaluating the 2nd
+      // operand: if this is also a list, all is ok.
+      // For "something . ...", "something - ..." or "non-list + ...",
+      // we know that the first operand needs to be a string or number
+      // without evaluating the 2nd operand.  So check before to avoid
+      // side effects after an error.
+      if (evaluate && !tv_check_str(rettv)) {
         tv_clear(rettv);
         return FAIL;
       }
@@ -3840,10 +3841,10 @@ static int eval5(char_u **arg, typval_T *rettv, int evaluate)
        */
       if (op == '.') {
         char buf1[NUMBUFLEN];
-        char_u buf2[NUMBUFLEN];
+        char buf2[NUMBUFLEN];
         // s1 already checked
         const char *const s1 = tv_get_string_buf(rettv, buf1);
-        const char *const s2 = (const char *)get_tv_string_buf_chk(&var2, buf2);
+        const char *const s2 = tv_get_string_buf_chk(&var2, buf2);
         if (s2 == NULL) {  // Type error?
           tv_clear(rettv);
           tv_clear(&var2);
@@ -4411,7 +4412,7 @@ eval_index (
       empty1 = true;
     } else if (eval1(arg, &var1, evaluate) == FAIL) {  // Recursive!
       return FAIL;
-    } else if (evaluate && get_tv_string_chk(&var1) == NULL) {
+    } else if (evaluate && !tv_check_str(&var1)) {
       // Not a number or string.
       tv_clear(&var1);
       return FAIL;
@@ -4430,7 +4431,7 @@ eval_index (
           tv_clear(&var1);
         }
         return FAIL;
-      } else if (evaluate && get_tv_string_chk(&var2) == NULL) {
+      } else if (evaluate && !tv_check_str(&var2)) {
         // Not a number or string.
         if (!empty1) {
           tv_clear(&var1);
@@ -4566,7 +4567,7 @@ eval_index (
         }
 
         if (len == -1) {
-          key = get_tv_string_chk(&var1);
+          key = (char_u *)tv_get_string_chk(&var1);
           if (key == NULL) {
             tv_clear(&var1);
             return FAIL;
@@ -5570,7 +5571,7 @@ static int get_dict_tv(char_u **arg, typval_T *rettv, int evaluate)
   char_u      *key = NULL;
   dictitem_T  *item;
   char_u      *start = skipwhite(*arg + 1);
-  char_u buf[NUMBUFLEN];
+  char buf[NUMBUFLEN];
 
   /*
    * First check if it's not a curly-braces thing: {expr}.
@@ -5602,9 +5603,9 @@ static int get_dict_tv(char_u **arg, typval_T *rettv, int evaluate)
       goto failret;
     }
     if (evaluate) {
-      key = get_tv_string_buf_chk(&tvkey, buf);
+      key = (char_u *)tv_get_string_buf_chk(&tvkey, buf);
       if (key == NULL) {
-        // "key" is NULL when get_tv_string_buf_chk() gave an errmsg
+        // "key" is NULL when tv_get_string_buf_chk() gave an errmsg
         tv_clear(&tvkey);
         goto failret;
       }
@@ -6598,7 +6599,6 @@ static void f_api_info(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 static void f_append(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
   long lnum;
-  char_u      *line;
   list_T      *l = NULL;
   listitem_T  *li = NULL;
   typval_T    *tv;
@@ -6622,21 +6622,23 @@ static void f_append(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       li = l->lv_first;
     }
     for (;; ) {
-      if (l == NULL)
-        tv = &argvars[1];               /* append a string */
-      else if (li == NULL)
-        break;                          /* end of list */
-      else
-        tv = &li->li_tv;                /* append item from list */
-      line = get_tv_string_chk(tv);
-      if (line == NULL) {               /* type error */
-        rettv->vval.v_number = 1;               /* Failed */
+      if (l == NULL) {
+        tv = &argvars[1];  // Append a string.
+      } else if (li == NULL) {
+        break;  // End of list.
+      } else {
+        tv = &li->li_tv;  // Append item from list.
+      }
+      const char *const line = tv_get_string_chk(tv);
+      if (line == NULL) {  // Type error.
+        rettv->vval.v_number = 1;  // Failed.
         break;
       }
-      ml_append(lnum + added, line, (colnr_T)0, FALSE);
-      ++added;
-      if (l == NULL)
+      ml_append(lnum + added, (char_u *)line, (colnr_T)0, false);
+      added++;
+      if (l == NULL) {
         break;
+      }
       li = li->li_next;
     }
 
@@ -6802,7 +6804,7 @@ static void f_assert_exception(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
   garray_T ga;
 
-  char *error = (char *)get_tv_string_chk(&argvars[0]);
+  const char *const error = tv_get_string_chk(&argvars[0]);
   if (vimvars[VV_EXCEPTION].vv_str == NULL) {
     prepare_assert_error(&ga);
     ga_concat(&ga, (char_u *)"v:exception is not set");
@@ -6821,22 +6823,22 @@ static void f_assert_exception(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 /// "assert_fails(cmd [, error])" function
 static void f_assert_fails(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  char_u *cmd = get_tv_string_chk(&argvars[0]);
+  const char *const cmd = tv_get_string_chk(&argvars[0]);
   garray_T    ga;
 
   called_emsg = false;
   suppress_errthrow = true;
   emsg_silent = true;
-  do_cmdline_cmd((char *)cmd);
+  do_cmdline_cmd(cmd);
   if (!called_emsg) {
     prepare_assert_error(&ga);
-    ga_concat(&ga, (char_u *)"command did not fail: ");
-    ga_concat(&ga, cmd);
+    ga_concat(&ga, (const char_u *)"command did not fail: ");
+    ga_concat(&ga, (const char_u *)cmd);
     assert_error(&ga);
     ga_clear(&ga);
   } else if (argvars[1].v_type != VAR_UNKNOWN) {
-    char_u buf[NUMBUFLEN];
-    char *error = (char *)get_tv_string_buf_chk(&argvars[1], buf);
+    char buf[NUMBUFLEN];
+    const char *const error = tv_get_string_buf_chk(&argvars[1], buf);
 
     if (error == NULL
         || strstr((char *)vimvars[VV_ERRMSG].vv_str, error) == NULL) {
@@ -6911,14 +6913,15 @@ static void f_assert_false(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
 static void assert_match_common(typval_T *argvars, assert_type_T atype)
 {
-  char_u buf1[NUMBUFLEN];
-  char_u buf2[NUMBUFLEN];
-  char_u *pat = get_tv_string_buf_chk(&argvars[0], buf1);
-  char_u *text = get_tv_string_buf_chk(&argvars[1], buf2);
+  char buf1[NUMBUFLEN];
+  char buf2[NUMBUFLEN];
+  const char *const pat = tv_get_string_buf_chk(&argvars[0], buf1);
+  const char *const text = tv_get_string_buf_chk(&argvars[1], buf2);
 
   if (pat == NULL || text == NULL) {
     EMSG(_(e_invarg));
-  } else if (pattern_match(pat, text, false) != (atype == ASSERT_MATCH)) {
+  } else if (pattern_match((char_u *)pat, (char_u *)text, false)
+             != (atype == ASSERT_MATCH)) {
     garray_T ga;
     prepare_assert_error(&ga);
     fill_assert_error(&ga, &argvars[2], NULL, &argvars[0], &argvars[1], atype);
@@ -7107,7 +7110,6 @@ static void f_bufname(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 static void f_bufnr(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
   bool error = false;
-  char_u *name;
 
   rettv->vval.v_number = -1;
   if (!tv_check_str_or_nr(&argvars[0])) {
@@ -7119,13 +7121,14 @@ static void f_bufnr(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   // If the buffer isn't found and the second argument is not zero create a
   // new buffer.
+  const char *name;
   if (buf == NULL
       && argvars[1].v_type != VAR_UNKNOWN
       && tv_get_number_chk(&argvars[1], &error) != 0
       && !error
-      && (name = get_tv_string_chk(&argvars[0])) != NULL
+      && (name = tv_get_string_chk(&argvars[0])) != NULL
       && !error) {
-    buf = buflist_new(name, NULL, (linenr_T)1, 0);
+    buf = buflist_new((char_u *)name, NULL, 1, 0);
   }
 
   if (buf != NULL) {
@@ -7190,24 +7193,23 @@ static void f_byte2line(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
 static void byteidx(typval_T *argvars, typval_T *rettv, int comp)
 {
-  char_u      *t;
-  char_u      *str;
-  long idx;
-
-  str = get_tv_string_chk(&argvars[0]);
-  idx = tv_get_number_chk(&argvars[1], NULL);
+  const char *const str = tv_get_string_chk(&argvars[0]);
+  varnumber_T idx = tv_get_number_chk(&argvars[1], NULL);
   rettv->vval.v_number = -1;
-  if (str == NULL || idx < 0)
+  if (str == NULL || idx < 0) {
     return;
+  }
 
-  t = str;
+  const char *t = str;
   for (; idx > 0; idx--) {
-    if (*t == NUL)              /* EOL reached */
+    if (*t == NUL) {  // EOL reached.
       return;
-    if (enc_utf8 && comp)
-      t += utf_ptr2len(t);
-    else
-      t += (*mb_ptr2len)(t);
+    }
+    if (enc_utf8 && comp) {
+      t += utf_ptr2len((const char_u *)t);
+    } else {
+      t += (*mb_ptr2len)((const char_u *)t);
+    }