* alloc.c: Remove unportable assumptions about struct layout.

(SDATA_SELECTOR, SDATA_DATA_OFFSET): New macros.
(SDATA_OF_STRING, SDATA_SIZE, allocate_string_data):
(allocate_vectorlike, make_pure_vector): Use the new macros,
plus offsetof, to remove unportable assumptions about struct layout.
These assumptions hold on all porting targets that I know of, but
they are not guaranteed, they're easy to remove, and removing them
makes further changes easier.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 81053d74480..b7a4a6701e0 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,14 @@
 2011-04-18  Paul Eggert  <eggert@cs.ucla.edu>
 
+        * alloc.c: Remove unportable assumptions about struct layout.
+        (SDATA_SELECTOR, SDATA_DATA_OFFSET): New macros.
+        (SDATA_OF_STRING, SDATA_SIZE, allocate_string_data):
+        (allocate_vectorlike, make_pure_vector): Use the new macros,
+        plus offsetof, to remove unportable assumptions about struct layout.
+        These assumptions hold on all porting targets that I know of, but
+        they are not guaranteed, they're easy to remove, and removing them
+        makes further changes easier.
+
         * alloc.c (BLOCK BYTES): Fix typo by changing "ablock" to "ablocks".
         This doesn't fix a bug but makes the code clearer.
         (string_overrun_cookie): Now const.  Use initializers that