[PATCH] manual: Document deviation of realloc from C2x/N2464

[Siddhesh Poyarekar]

Explicitly note that the realloc behaviour chosen in glibc is deliberate
and well defined and suggest that strictly compliant code should avoid
passing zero to realloc.

Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
---
 manual/memory.texi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/manual/memory.texi b/manual/memory.texi
index 5781a64f35..7697a10f72 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -832,6 +832,11 @@ space is available.  The value of @code{realloc} is the new address of the
 block.  If the block needs to be moved, @code{realloc} copies the old
 contents.
 
+The ISO C2x standard regards a zero value for @var{newsize} as undefined
+through N2464, so code that aims to be strictly compliant should avoid passing
+zero as @var{newsize} to @code{realloc}.  @Theglibc{} behavior however is well
+defined below.
+
 If you pass a null pointer for @var{ptr}, @code{realloc} behaves just
 like @samp{malloc (@var{newsize})}.
 Otherwise, if @var{newsize} is zero
-- 
2.40.1