Noteworthy GCC changes in version 2.4:

* On each target, the default is now to return short structures
compatibly with the "usual" compiler on that target.

For most targets, this means the default is to return all structures
in memory, like long structures, in whatever way is used on that
target.  Use -freg-struct-return to enable returning short structures
(and unions) in registers.

This change means that newly compiled binaries are incompatible with
binaries compiled with previous versions of GCC.

On some targets, GCC is itself the usual compiler.  On these targets,
the default way to return short structures is still in registers.
Use -fpcc-struct-return to tell GCC to return them in memory.

* There is now a floating point emulator which can imitate the way all
supported target machines do floating point arithmetic.

This makes it possible to have cross compilation to and from the VAX,
and between machines of different endianness.  However, this works
only when the target machine description is updated to use the new
facilities, and not all have been updated.

This also makes possible support for longer floating point types.
GCC 2.4 supports extended format on the 68K if you use `long double',
for targets that have a 68881.  (When we have run time library
routines for extended floating point, then `long double' will use
extended format on all 68K targets.)

We expect to support extended floating point on the i386 and Sparc in
future versions.

* Building GCC now automatically fixes the system's header files.
This should require no attention.

* GCC now installs an unsigned data type as size_t when it fixes the
header files (on all but a handful of old target machines).
Therefore, the bug that size_t failed to be unsigned is fixed.

* Building and installation are now completely separate.
All new files are constructed during the build process; 
installation just copies them.

* New targets supported: Clipper, Hitachi SH, Hitachi 8300, and Sparc
Lite.

* A totally new and much better Objective C run time system is included.

* Objective C supports many new features.  Alas, I can't describe them
since I don't use that language; however, they are the same ones 
supported in recent versions of the NeXT operating system.

* The builtin functions __builtin_apply_args, __builtin_apply and
__builtin_return let you record the arguments and returned
value of a function without knowing their number or type.

* The builtin string variables __FUNCTION__ and __PRETTY_FUNCTION__
give the name of the function in the source, and a pretty-printed
version of the name.  The two are the same in C, but differ in C++.

* Casts to union types do not yield lvalues.

* ## before an empty rest argument discards the preceding sequence
of non-whitespace characters from the macro definition.
(This feature is subject to change.)


New features specific to C++:

* The manual contains a new section ``Common Misunderstandings with
GNU C++'' that C++ users should read.

* #pragma interface and #pragma implementation let you use the same
C++ source file for both interface and implementation.
However, this mechanism is still in transition.

* Named returned values let you avoid an extra constructor call
when a function result has a class type.

* The C++ operators <? and >? yield min and max, respectively.

* C++ gotos can exit a block safely even if the block has
aggregates that require destructors.

* gcc defines the macro __GNUG__ when compiling C++ programs.

* GNU C++ now correctly distinguishes between the prefix and postfix
forms of overloaded operator ++ and --.  To avoid breaking old
code, if a class defines only the prefix form, the compiler
accepts either ++obj or obj++, unless -pedantic is used.

* If you are using version 2.3 of libg++, you need to rebuild it with
`make CC=gcc' to avoid mismatches in the definition of `size_t'.


Newly documented compiler options:

-fnostartfiles
	Omit the standard system startup files when linking.

-fvolatile-global
	Consider memory references to extern and global data items to
	be volatile.

-idirafter DIR
	Add DIR to the second include path.

-iprefix PREFIX
	Specify PREFIX for later -iwithprefix options.

-iwithprefix DIR
	Add PREFIX/DIR to the second include path.

-mv8
	Emit Sparc v8 code (with integer multiply and divide).
-msparclite
	Emit Sparclite code (roughly v7.5).

-print-libgcc-file-name
	Search for the libgcc.a file, print its absolute file name, and exit.

-Woverloaded-virtual
	Warn when a derived class function declaration may be an error
	in defining a C++ virtual function. 

-Wtemplate-debugging
	When using templates in a C++ program, warn if debugging is
	not yet fully available.

+eN
	Control how C++ virtual function definitions are used
	(like cfront 1.x).
