No OOM in enc_canonize()

Fix a `return FAIL` that should be `return NULL` in `enc_locale()`

src/nvim/ex_cmds2.c

@@ -3012,8 +3012,6 @@ void ex_scriptencoding(exarg_T *eap)
 
   if (*eap->arg != NUL) {
     name = enc_canonize(eap->arg);
-    if (name == NULL)           /* out of memory */
-      return;
   } else
     name = eap->arg;
 

src/nvim/fileio.c

@@ -2087,10 +2087,7 @@ void set_forced_fenc(exarg_T *eap)
 {
   if (eap->force_enc != 0) {
     char_u *fenc = enc_canonize(eap->cmd + eap->force_enc);
-
-    if (fenc != NULL)
-      set_string_option_direct((char_u *)"fenc", -1,
-          fenc, OPT_FREE|OPT_LOCAL, 0);
+    set_string_option_direct((char_u *)"fenc", -1, fenc, OPT_FREE|OPT_LOCAL, 0);
     free(fenc);
   }
 }

src/nvim/mbyte.c

@@ -84,6 +84,7 @@
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/fileio.h"
+#include "nvim/func_attr.h"
 #include "nvim/memline.h"
 #include "nvim/message.h"
 #include "nvim/misc1.h"
@@ -3308,24 +3309,23 @@ char_u * enc_skip(char_u *p)
  * Find the canonical name for encoding "enc".
  * When the name isn't recognized, returns "enc" itself, but with all lower
  * case characters and '_' replaced with '-'.
- * Returns an allocated string.  NULL for out-of-memory.
+ * Returns an allocated string.
  */
-char_u * enc_canonize(char_u *enc)
+char_u *enc_canonize(char_u *enc) FUNC_ATTR_NONNULL_RET
 {
-  char_u      *r;
   char_u      *p, *s;
   int i;
 
   if (STRCMP(enc, "default") == 0) {
     /* Use the default encoding as it's found by set_init_1(). */
-    r = get_encoding_default();
+    char_u *r = get_encoding_default();
     if (r == NULL)
       r = (char_u *)"latin1";
     return vim_strsave(r);
   }
 
   /* copy "enc" to allocated memory, with room for two '-' */
-  r = xmalloc(STRLEN(enc) + 3);
+  char_u *r = xmalloc(STRLEN(enc) + 3);
   /* Make it all lower case and replace '_' with '-'. */
   p = r;
   for (s = enc; *s != NUL; ++s) {
@@ -3411,7 +3411,7 @@ char_u * enc_locale()
           s = (char *)os_getenv("LANG");
 
   if (s == NULL || *s == NUL)
-    return FAIL;
+    return NULL;
 
   /* The most generic locale format is:
    * language[_territory][.codeset][@modifier][+special][,[sponsor][_revision]]

src/nvim/option.c

@@ -3971,10 +3971,8 @@ did_set_string_option (
     if (errmsg == NULL) {
       /* canonize the value, so that STRCMP() can be used on it */
       p = enc_canonize(*varp);
-      if (p != NULL) {
-        free(*varp);
-        *varp = p;
-      }
+      free(*varp);
+      *varp = p;
       if (varp == &p_enc) {
         errmsg = mb_init();
         redraw_titles();
@@ -4000,18 +3998,8 @@ did_set_string_option (
   } else if (varp == &p_penc) {
     /* Canonize printencoding if VIM standard one */
     p = enc_canonize(p_penc);
-    if (p != NULL) {
-      free(p_penc);
-      p_penc = p;
-    } else {
-      /* Ensure lower case and '-' for '_' */
-      for (s = p_penc; *s != NUL; s++) {
-        if (*s == '_')
-          *s = '-';
-        else
-          *s = TOLOWER_ASC(*s);
-      }
-    }
+    free(p_penc);
+    p_penc = p;
   } else if (varp == &curbuf->b_p_keymap) {
     /* load or unload key mapping tables */
     errmsg = keymap_init();

src/nvim/spell.c

@@ -4438,7 +4438,7 @@ static afffile_T *spell_read_aff(spellinfo_T *spin, char_u *fname)
       if (is_aff_rule(items, itemcnt, "SET", 2) && aff->af_enc == NULL) {
         // Setup for conversion from "ENC" to 'encoding'.
         aff->af_enc = enc_canonize(items[1]);
-        if (aff->af_enc != NULL && !spin->si_ascii
+        if (!spin->si_ascii
             && convert_setup(&spin->si_conv, aff->af_enc,
                 p_enc) == FAIL)
           smsg((char_u *)_("Conversion in %s not supported: from %s to %s"),
@@ -5978,7 +5978,7 @@ static int spell_read_wordfile(spellinfo_T *spin, char_u *fname)
           // Setup for conversion to 'encoding'.
           line += 9;
           enc = enc_canonize(line);
-          if (enc != NULL && !spin->si_ascii
+          if (!spin->si_ascii
               && convert_setup(&spin->si_conv, enc,
                   p_enc) == FAIL)
             smsg((char_u *)_("Conversion in %s not supported: from %s to %s"),