Use C99-style flexible array members if available.

This avoids some subtle aliasing issues, which typically
aren't a problem with GCC but may be a problem elsewhere.
* lib-src/ebrowse.c (struct member, struct alias, struct sym):
Use FLEXIBLE_ARRAY_MEMBER.
(add_sym, add_member, make_namespace, register_namespace_alias):
Use offsetof (struct, flex_array_member), not sizeof (struct), as
that ports better to pre-C99 non-GCC.
* src/alloc.c (sdata): New typedef, replacing the old struct sdata.
It is a struct if GC_CHECK_STRING_BYTES, a union otherwise.
In either case, it uses a flexible array member rather than
the old struct hack.  All uses changed.
(SDATA_NBYTES, sweep_strings) [!GC_CHECK_STRING_BYTES]:
Adjust to sdata reorganization.
* src/alloc.c (VBLOCK_BYTES_MIN, allocate_vectorlike, Fgarbage_collect):
Use offsetof (struct, flex_array_member), not sizeof (struct), as
that ports better to pre-C99 non-GCC.
* src/chartab.c (Fmake_char_table, make_sub_char_table, copy_char_table):
Use CHAR_TABLE_STANDARD_SLOTS rather than its definition,
as the latter has changed.
* src/conf_post.h (FLEXIBLE_ARRAY_MEMBER): Move here from w32.c,
and port better to pre-C99 GCC.
* src/image.c (struct xpm_cached_color):
* src/lisp.h (struct Lisp_Vector, struct Lisp_Bool_Vector)
(struct Lisp_Char_Table, struct Lisp_Sub_Char_Table):
Use FLEXIBLE_ARRAY_MEMBER.
* src/lisp.h (string_bytes) [GC_CHECK_STRING_BYTES]:
Move decl to top level so it gets checked against implementation.
(CHAR_TABLE_STANDARD_SLOTS): Adjust to struct Lisp_Char_Table change.
* src/w32.c (FLEXIBLE_ARRAY_MEMBER): Move to conf_post.h.

1 files changed, 10 insertions, 9 deletions

diff --git a/lib-src/ebrowse.c b/lib-src/ebrowse.c
index 3a237daf5f8..81d0cf0a19e 100644
--- a/lib-src/ebrowse.c
+++ b/lib-src/ebrowse.c
@@ -237,7 +237,7 @@ struct member
   char *def_regexp;             /* Regular expression matching definition.  */
   const char *def_filename;     /* File name of definition.  */
   int def_pos;                  /* Buffer position of definition.  */
-  char name[1];                 /* Member name.  */
+  char name[FLEXIBLE_ARRAY_MEMBER]; /* Member name.  */
 };
 
 /* Structures of this type are used to connect class structures with
@@ -256,7 +256,7 @@ struct alias
   struct alias *next;           /* Next in list.  */
   struct sym *namesp;           /* Namespace in which defined.  */
   struct link *aliasee;         /* List of aliased namespaces (A::B::C...).  */
-  char name[1];                 /* Alias name.  */
+  char name[FLEXIBLE_ARRAY_MEMBER]; /* Alias name.  */
 };
 
 /* The structure used to describe a class in the symbol table,
@@ -280,7 +280,7 @@ struct sym
   const char *filename;         /* File in which it can be found.  */
   const char *sfilename;        /* File in which members can be found.  */
   struct sym *namesp;           /* Namespace in which defined. .  */
-  char name[1];                 /* Name of the class.  */
+  char name[FLEXIBLE_ARRAY_MEMBER]; /* Name of the class.  */
 };
 
 /* Experimental: Print info for `--position-info'.  We print
@@ -567,8 +567,8 @@ add_sym (const char *name, struct sym *nested_in_class)
           puts (name);
         }
 
-      sym = (struct sym *) xmalloc (sizeof *sym + strlen (name));
-      memset (sym, 0, sizeof *sym);
+      sym = xmalloc (offsetof (struct sym, name) + strlen (name) + 1);
+      memset (sym, 0, offsetof (struct sym, name));
       strcpy (sym->name, name);
       sym->namesp = scope;
       sym->next = class_table[h];
@@ -852,7 +852,8 @@ add_global_decl (char *name, char *regexp, int pos, unsigned int hash, int var,
 static struct member *
 add_member (struct sym *cls, char *name, int var, int sc, unsigned int hash)
 {
-  struct member *m = (struct member *) xmalloc (sizeof *m + strlen (name));
+  struct member *m = xmalloc (offsetof (struct member, name)
+                              + strlen (name) + 1);
   struct member **list;
   struct member *p;
   struct member *prev;
@@ -962,8 +963,8 @@ mark_inherited_virtual (void)
 static struct sym *
 make_namespace (char *name, struct sym *context)
 {
-  struct sym *s = (struct sym *) xmalloc (sizeof *s + strlen (name));
-  memset (s, 0, sizeof *s);
+  struct sym *s = xmalloc (offsetof (struct sym, name) + strlen (name) + 1);
+  memset (s, 0, offsetof (struct sym, name));
   strcpy (s->name, name);
   s->next = all_namespaces;
   s->namesp = context;
@@ -1046,7 +1047,7 @@ register_namespace_alias (char *new_name, struct link *old_name)
     if (streq (new_name, al->name) && (al->namesp == current_namespace))
       return;
 
-  al = (struct alias *) xmalloc (sizeof *al + strlen (new_name));
+  al = xmalloc (offsetof (struct alias, name) + strlen (new_name) + 1);
   strcpy (al->name, new_name);
   al->next = namespace_alias_table[h];
   al->namesp = current_namespace;