[PATCH 2/8] Fix const casts and use const where needed

Found with -Wcast-qual.
---
 addrbook.c |  8 ++++----
 browser.c  | 24 ++++++++++++------------
 hash.c     |  4 ++--
 listmenu.c |  4 ++--
 pager.c    |  6 +++---
 pgpkey.c   | 16 ++++++++--------
 rfc3676.c  |  2 +-
 sort.c     | 43 ++++++++++++++++++++++---------------------
 thread.c   | 22 ++++++++++++----------
 9 files changed, 66 insertions(+), 63 deletions(-)

diff --git a/addrbook.c b/addrbook.c
index 6175e39a..924a2c3e 100644
--- a/addrbook.c
+++ b/addrbook.c
@@ -95,8 +95,8 @@ static int alias_tag(MUTTMENU *menu, int n, int m)
 
 static int alias_SortAlias(const void *a, const void *b)
 {
-  ALIAS *pa = *(ALIAS **) a;
-  ALIAS *pb = *(ALIAS **) b;
+  const ALIAS *pa = *(const ALIAS * const *) a;
+  const ALIAS *pb = *(const ALIAS * const *) b;
   int r = mutt_strcasecmp(pa->name, pb->name);
 
   return (RSORT(r));
@@ -104,8 +104,8 @@ static int alias_SortAlias(const void *a, const void *b)
 
 static int alias_SortAddress(const void *a, const void *b)
 {
-  ADDRESS *pa = (*(ALIAS **) a)->addr;
-  ADDRESS *pb = (*(ALIAS **) b)->addr;
+  const ADDRESS *pa = (*(ALIAS * const *) a)->addr;
+  const ADDRESS *pb = (*(ALIAS * const *) b)->addr;
   int r;
 
   if (pa == pb)
diff --git a/browser.c b/browser.c
index 82f138ab..7f3498ce 100644
--- a/browser.c
+++ b/browser.c
@@ -86,8 +86,8 @@ static int sort_reverse_flag = 0;
 
 static int browser_compare_order(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_numeric_cmp(pa->number, pb->number);
 
@@ -96,8 +96,8 @@ static int browser_compare_order(const void *a, const void *b)
 
 static int browser_compare_subject(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_strcoll(pa->display_name, pb->display_name);
 
@@ -106,8 +106,8 @@ static int browser_compare_subject(const void *a, const void *b)
 
 static int browser_compare_date(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_numeric_cmp(pa->mtime, pb->mtime);
 
@@ -116,8 +116,8 @@ static int browser_compare_date(const void *a, const void *b)
 
 static int browser_compare_size(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_numeric_cmp(pa->size, pb->size);
 
@@ -126,8 +126,8 @@ static int browser_compare_size(const void *a, const void *b)
 
 static int browser_compare_count(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_numeric_cmp(pa->msg_count, pb->msg_count);
 
@@ -136,8 +136,8 @@ static int browser_compare_count(const void *a, const void *b)
 
 static int browser_compare_unread(const void *a, const void *b)
 {
-  struct folder_file *pa = (struct folder_file *) a;
-  struct folder_file *pb = (struct folder_file *) b;
+  const struct folder_file *pa = (const struct folder_file *) a;
+  const struct folder_file *pb = (const struct folder_file *) b;
 
   int r = mutt_numeric_cmp(pa->msg_unread, pb->msg_unread);
 
diff --git a/hash.c b/hash.c
index dff38e86..e0860aea 100644
--- a/hash.c
+++ b/hash.c
@@ -32,7 +32,7 @@
 static unsigned int gen_string_hash(union hash_key key, unsigned int n)
 {
   unsigned int h = 0;
-  unsigned char *s = (unsigned char *)key.strkey;
+  const unsigned char *s = (const unsigned char *)key.strkey;
 
   while (*s)
     h += (h << 7) + *s++;
@@ -49,7 +49,7 @@ static int cmp_string_key(union hash_key a, union hash_key b)
 static unsigned int gen_case_string_hash(union hash_key key, unsigned int n)
 {
   unsigned int h = 0;
-  unsigned char *s = (unsigned char *)key.strkey;
+  const unsigned char *s = (const unsigned char *)key.strkey;
 
   while (*s)
     h += (h << 7) + tolower(*s++);
diff --git a/listmenu.c b/listmenu.c
index 46bd8d8b..02bfc074 100644
--- a/listmenu.c
+++ b/listmenu.c
@@ -158,10 +158,10 @@ static void list_headers_free(struct list_headers **p_lhdrs)
 static void make_field_format(int max, char *dst)
 {
   int len = 0;
-  struct mapping_t *action;
+  const struct mapping_t *action;
 
   dst[--max] = '\0';
-  for (action = (struct mapping_t *)ListActions; action->name; action++)
+  for (action = (const struct mapping_t *)ListActions; action->name; action++)
     len = MAX(len, mutt_strwidth(_(action->name)));
 
   /* n.b. not localized - is a metaformat */
diff --git a/pager.c b/pager.c
index c67eb3a8..a9c30dbd 100644
--- a/pager.c
+++ b/pager.c
@@ -425,7 +425,7 @@ classify_quote(struct q_class_t **QuoteList, const char *qptr,
 {
   struct q_class_t *q_list = *QuoteList;
   struct q_class_t *class = NULL, *tmp = NULL, *ptr, *save;
-  char *tail_qptr;
+  const char *tail_qptr;
   int offset, tail_lng;
   int index = -1;
 
@@ -554,7 +554,7 @@ classify_quote(struct q_class_t **QuoteList, const char *qptr,
 
         q_list = q_list->down;
         tail_lng = length - offset;
-        tail_qptr = (char *) qptr + offset;
+        tail_qptr = qptr + offset;
 
         while (q_list)
         {
@@ -657,7 +657,7 @@ classify_quote(struct q_class_t **QuoteList, const char *qptr,
 
               q_list = q_list->down;
               tail_lng = length - offset;
-              tail_qptr = (char *) qptr + offset;
+              tail_qptr = qptr + offset;
 
               continue;
             }
diff --git a/pgpkey.c b/pgpkey.c
index dcbeee48..a6532e4c 100644
--- a/pgpkey.c
+++ b/pgpkey.c
@@ -300,8 +300,8 @@ static int _pgp_compare_address(const void *a, const void *b)
 {
   int r;
 
-  pgp_uid_t **s = (pgp_uid_t **) a;
-  pgp_uid_t **t = (pgp_uid_t **) b;
+  const pgp_uid_t * const *s = (const pgp_uid_t * const *) a;
+  const pgp_uid_t * const *t = (const pgp_uid_t * const *) b;
 
   if ((r = mutt_strcasecmp((*s)->addr, (*t)->addr)))
     return r;
@@ -322,8 +322,8 @@ static int _pgp_compare_keyid(const void *a, const void *b)
 {
   int r;
 
-  pgp_uid_t **s = (pgp_uid_t **) a;
-  pgp_uid_t **t = (pgp_uid_t **) b;
+  const pgp_uid_t * const *s = (const pgp_uid_t * const *) a;
+  const pgp_uid_t * const *t = (const pgp_uid_t * const *) b;
 
   if ((r = mutt_strcasecmp(pgp_fpr_or_lkeyid((*s)->parent),
                            pgp_fpr_or_lkeyid((*t)->parent))))
@@ -341,8 +341,8 @@ static int pgp_compare_keyid(const void *a, const void *b)
 static int _pgp_compare_date(const void *a, const void *b)
 {
   int r;
-  pgp_uid_t **s = (pgp_uid_t **) a;
-  pgp_uid_t **t = (pgp_uid_t **) b;
+  const pgp_uid_t * const *s = (const pgp_uid_t * const *) a;
+  const pgp_uid_t * const *t = (const pgp_uid_t * const *) b;
 
   if ((r = mutt_numeric_cmp((*s)->parent->gen_time, (*t)->parent->gen_time)))
     return r;
@@ -359,8 +359,8 @@ static int _pgp_compare_trust(const void *a, const void *b)
 {
   int r;
 
-  pgp_uid_t **s = (pgp_uid_t **) a;
-  pgp_uid_t **t = (pgp_uid_t **) b;
+  const pgp_uid_t * const *s = (const pgp_uid_t * const *) a;
+  const pgp_uid_t * const *t = (const pgp_uid_t * const *) b;
 
   if ((r = mutt_numeric_cmp(((*s)->parent->flags & (KEYFLAG_RESTRICTIONS)),
                             ((*t)->parent->flags & (KEYFLAG_RESTRICTIONS)))))
diff --git a/rfc3676.c b/rfc3676.c
index 48128a3d..ebb5cbdc 100644
--- a/rfc3676.c
+++ b/rfc3676.c
@@ -51,7 +51,7 @@ typedef struct flowed_state
 static int get_quote_level(const char *line)
 {
   int quoted = 0;
-  char *p = (char *) line;
+  const char *p = line;
 
   while (p && *p == '>')
   {
diff --git a/sort.c b/sort.c
index ce6f9e0e..f818a531 100644
--- a/sort.c
+++ b/sort.c
@@ -31,29 +31,29 @@
 
 static int compare_score(const void *a, const void *b)
 {
-  HEADER **pa = (HEADER **) a;
-  HEADER **pb = (HEADER **) b;
+  const HEADER * const *pa = (const HEADER * const *) a;
+  const HEADER * const *pb = (const HEADER * const *) b;
   return mutt_numeric_cmp((*pb)->score, (*pa)->score); /* note that this is reverse */
 }
 
 static int compare_size(const void *a, const void *b)
 {
-  HEADER **pa = (HEADER **) a;
-  HEADER **pb = (HEADER **) b;
+  const HEADER * const *pa = (const HEADER * const *) a;
+  const HEADER * const *pb = (const HEADER * const *) b;
   return mutt_numeric_cmp((*pa)->content->length, (*pb)->content->length);
 }
 
 static int compare_date_sent(const void *a, const void *b)
 {
-  HEADER **pa = (HEADER **) a;
-  HEADER **pb = (HEADER **) b;
+  const HEADER * const *pa = (const HEADER * const *) a;
+  const HEADER * const *pb = (const HEADER * const *) b;
   return mutt_numeric_cmp((*pa)->date_sent, (*pb)->date_sent);
 }
 
 static int compare_subject(const void *a, const void *b)
 {
-  HEADER **pa = (HEADER **) a;
-  HEADER **pb = (HEADER **) b;
+  const HEADER * const *pa = (const HEADER * const *) a;
+  const HEADER * const *pb = (const HEADER * const *) b;
   int rc;
 
   if (!(*pa)->env->real_subj)
@@ -89,8 +89,8 @@ const char *mutt_get_name(ADDRESS *a)
 
 static int compare_to(const void *a, const void *b)
 {
-  HEADER **ppa = (HEADER **) a;
-  HEADER **ppb = (HEADER **) b;
+  const HEADER * const *ppa = (const HEADER * const *) a;
+  const HEADER * const *ppb = (const HEADER * const *) b;
   char fa[SHORT_STRING];
   const char *fb;
 
@@ -101,8 +101,8 @@ static int compare_to(const void *a, const void *b)
 
 static int compare_from(const void *a, const void *b)
 {
-  HEADER **ppa = (HEADER **) a;
-  HEADER **ppb = (HEADER **) b;
+  const HEADER * const *ppa = (const HEADER * const *) a;
+  const HEADER * const *ppb = (const HEADER * const *) b;
   char fa[SHORT_STRING];
   const char *fb;
 
@@ -113,23 +113,23 @@ static int compare_from(const void *a, const void *b)
 
 static int compare_date_received(const void *a, const void *b)
 {
-  HEADER **pa = (HEADER **) a;
-  HEADER **pb = (HEADER **) b;
+  const HEADER * const *pa = (const HEADER * const *) a;
+  const HEADER * const *pb = (const HEADER * const *) b;
   return mutt_numeric_cmp((*pa)->received, (*pb)->received);
 }
 
 static int compare_order(const void *a, const void *b)
 {
-  HEADER **ha = (HEADER **) a;
-  HEADER **hb = (HEADER **) b;
+  const HEADER * const *ha = (const HEADER * const *) a;
+  const HEADER * const *hb = (const HEADER * const *) b;
 
   return mutt_numeric_cmp((*ha)->index, (*hb)->index);
 }
 
 static int compare_spam(const void *a, const void *b)
 {
-  HEADER **ppa = (HEADER **) a;
-  HEADER **ppb = (HEADER **) b;
+  const HEADER * const *ppa = (const HEADER * const *) a;
+  const HEADER * const *ppb = (const HEADER * const *) b;
   char   *aptr, *bptr;
   int     ahas, bhas;
   int     result = 0;
@@ -176,8 +176,8 @@ static int compare_spam(const void *a, const void *b)
 
 static int compare_label(const void *a, const void *b)
 {
-  HEADER **ppa = (HEADER **) a;
-  HEADER **ppb = (HEADER **) b;
+  const HEADER * const *ppa = (const HEADER * const *) a;
+  const HEADER * const *ppb = (const HEADER * const *) b;
   int     ahas, bhas;
 
   /* As with compare_spam, not all messages will have the x-label
@@ -251,7 +251,8 @@ static int compare_unthreaded(const void *a, const void *b)
   if (rc)
     return (SortAux & SORT_REVERSE) ? -rc : rc;
 
-  rc = mutt_numeric_cmp((*((HEADER **)a))->index, (*((HEADER **)b))->index);
+  rc = mutt_numeric_cmp((*((const HEADER * const *) a))->index,
+                        (*((const HEADER * const *) b))->index);
   if (rc)
     return (Sort & SORT_REVERSE) ? -rc : rc;
 
diff --git a/thread.c b/thread.c
index c67a3f78..4d388711 100644
--- a/thread.c
+++ b/thread.c
@@ -589,13 +589,13 @@ static int compare_aux_threads(const void *a, const void *b)
     return aux_func ? 1 : 0;
   }
 
-  rc = (*aux_func)(&(*((THREAD **) a))->sort_aux_key,
-                   &(*((THREAD **) b))->sort_aux_key);
+  rc = (*aux_func)(&(*((const THREAD * const *) a))->sort_aux_key,
+                   &(*((const THREAD * const *) b))->sort_aux_key);
   if (rc)
     return (SortAux & SORT_REVERSE) ? -rc : rc;
 
-  rc = mutt_numeric_cmp((*((THREAD **)a))->sort_aux_key->index,
-                        (*((THREAD **)b))->sort_aux_key->index);
+  rc = mutt_numeric_cmp((*((const THREAD * const *) a))->sort_aux_key->index,
+                        (*((const THREAD * const *) b))->sort_aux_key->index);
   if (rc)
     return (SortAux & SORT_REVERSE) ? -rc : rc;
 
@@ -623,7 +623,8 @@ static int compare_aux_sortkeys(const void *a, const void *b)
   if (rc)
     return rc;
 
-  return mutt_numeric_cmp((*((HEADER **)a))->index, (*((HEADER **)b))->index);
+  return mutt_numeric_cmp((*((const HEADER * const *) a))->index,
+                          (*((const HEADER * const *) b))->index);
 }
 
 static int compare_root_threads(const void *a, const void *b)
@@ -648,13 +649,13 @@ static int compare_root_threads(const void *a, const void *b)
     return sort_func ? 1 : 0;
   }
 
-  rc = (*sort_func)(&(*((THREAD **) a))->sort_group_key,
-                    &(*((THREAD **) b))->sort_group_key);
+  rc = (*sort_func)(&(*((const THREAD * const *) a))->sort_group_key,
+                    &(*((const THREAD * const *) b))->sort_group_key);
   if (rc)
     return reverse ? -rc : rc;
 
-  rc = mutt_numeric_cmp((*((THREAD **)a))->sort_group_key->index,
-                        (*((THREAD **)b))->sort_group_key->index);
+  rc = mutt_numeric_cmp((*((const THREAD * const *) a))->sort_group_key->index,
+                        (*((const THREAD * const *) b))->sort_group_key->index);
   if (rc)
     return reverse ? -rc : rc;
 
@@ -687,7 +688,8 @@ static int compare_group_sortkeys(const void *a, const void *b)
   if (rc)
     return rc;
 
-  return mutt_numeric_cmp((*((HEADER **)a))->index, (*((HEADER **)b))->index);
+  return mutt_numeric_cmp((*((const HEADER * const *) a))->index,
+                          (*((const HEADER * const *) b))->index);
 }
 
 THREAD *mutt_sort_subthreads(THREAD *thread, int init)
-- 
2.51.0