Merge branch 'jk/tighten-alloc' into maint

Protect our code from over-eager compilers.

* jk/tighten-alloc:
  inline xalloc_flex() into FLEXPTR_ALLOC_MEM
  avoid pointer arithmetic involving NULL in FLEX_ALLOC_MEM

git-compat-util.h

@@ -848,11 +848,14 @@ static inline void copy_array(void *dst, const void *src, size_t n, size_t size)
  * times, and it must be assignable as an lvalue.
  */
 #define FLEX_ALLOC_MEM(x, flexname, buf, len) do { \
-	(x) = NULL; /* silence -Wuninitialized for offset calculation */ \
-	(x) = xalloc_flex(sizeof(*(x)), (char *)(&((x)->flexname)) - (char *)(x), (buf), (len)); \
+	size_t flex_array_len_ = (len); \
+	(x) = xcalloc(1, st_add3(sizeof(*(x)), flex_array_len_, 1)); \
+	memcpy((void *)(x)->flexname, (buf), flex_array_len_); \
 } while (0)
 #define FLEXPTR_ALLOC_MEM(x, ptrname, buf, len) do { \
-	(x) = xalloc_flex(sizeof(*(x)), sizeof(*(x)), (buf), (len)); \
+	size_t flex_array_len_ = (len); \
+	(x) = xcalloc(1, st_add3(sizeof(*(x)), flex_array_len_, 1)); \
+	memcpy((x) + 1, (buf), flex_array_len_); \
 	(x)->ptrname = (void *)((x)+1); \
 } while(0)
 #define FLEX_ALLOC_STR(x, flexname, str) \
@@ -860,14 +863,6 @@ static inline void copy_array(void *dst, const void *src, size_t n, size_t size)
 #define FLEXPTR_ALLOC_STR(x, ptrname, str) \
 	FLEXPTR_ALLOC_MEM((x), ptrname, (str), strlen(str))
 
-static inline void *xalloc_flex(size_t base_len, size_t offset,
-				const void *src, size_t src_len)
-{
-	unsigned char *ret = xcalloc(1, st_add3(base_len, src_len, 1));
-	memcpy(ret + offset, src, src_len);
-	return ret;
-}
-
 static inline char *xstrdup_or_null(const char *str)
 {
 	return str ? xstrdup(str) : NULL;