Don't discuss details of what type size_t might be typedefed to

["Joseph S. Myers" <joseph at codesourcery dot com>]

As a third piece of removing inappropriate references to the GNU
system, I propose this patch removing a statement about the types to
which size_t may be equivalent, and the following discussion about
when two integer types, of the same size and signedness, are different
in a way that matters.

The statement that size_t is one of unsigned int or unsigned long int
*is* true for anything that might be called a GNU system - the GNU
Coding Standards specifically say that portability to systems where
size_t is unsigned long long int, wider than unsigned long int, does
not matter, so I think we can assume such systems will not be GNU
systems.  But I don't think that's a relevant detail for the glibc
manual.  The statement that the two possible types are equivalent is
only true for 32-bit systems, so making this text accurate as a whole
would involve complicating it with conditionals about 64-bit systems.
And the discussion of how the types being distinct matters for
declaring a system function is about something of little current
relevance - nowadays people just get prototype declarations of system
functions from the system headers.  So I think it's best just to
describe size_t abstractly without detailing particular types it might
be equivalent to.

lang.texi has yet another phrase for GNU system or library variants,
"GNU C system".  I'm inclined to think, from other similar entries,
that this is a synonym for "GNU C library".

2012-02-27  Joseph Myers  <joseph@codesourcery.com>

	* manual/lang.texi (size_t): Do not describe particular types to
	which size_t is equivalent or when differences between them are
	significant.

diff --git a/manual/lang.texi b/manual/lang.texi
index b93ad5b..70471d3 100644
--- a/manual/lang.texi
+++ b/manual/lang.texi
@@ -635,21 +635,6 @@ this type to specify object sizes.
 arguments or variables that hold the size of an object.
 @end deftp
 
-In the GNU system @code{size_t} is equivalent to either
-@w{@code{unsigned int}} or @w{@code{unsigned long int}}.  These types
-have identical properties on the GNU system and, for most purposes, you
-can use them interchangeably.  However, they are distinct as data types,
-which makes a difference in certain contexts.
-
-For example, when you specify the type of a function argument in a
-function prototype, it makes a difference which one you use.  If the
-system header files declare @code{malloc} with an argument of type
-@code{size_t} and you declare @code{malloc} with an argument of type
-@code{unsigned int}, you will get a compilation error if @code{size_t}
-happens to be @code{unsigned long int} on your system.  To avoid any
-possibility of error, when a function argument or value is supposed to
-have type @code{size_t}, never declare its type in any other way.
-
 @strong{Compatibility Note:} Implementations of C before the advent of
 @w{ISO C} generally used @code{unsigned int} for representing object sizes
 and @code{int} for pointer subtraction results.  They did not


-- 
Joseph S. Myers
joseph@codesourcery.com