[GCC-XML]Re-write prototype in CVS

[Brad King]

Hello, all:

I have finally found enough time to finish off the first version of
the re-write of GCC-XML.  The new version has been committed to the
main branch of the CVS repository.  A new GCC patch has been provided
that should work with GCC 3.0.4.

The version of GCC-XML that existed prior to this checkin has been
branched from the main tree.  Anyone who still wants to use that
version should do

  cvs update -r declaration-style

to move over to the branch.

Output from the new version is almost completely different from
previous versions, and is not at all backward-compatible.  It is
organized as a set of nodes in a graph.  Each node has an id that can
be referenced by other nodes, and is dumped as its own XML element.
There is no nesting of XML elements because nesting reflects a tree
structure, not a graph.

This is the first version of GCC-XML to support partial dumps.  There
is a new option that allows specification of where to start:

gccxml ... -fxml=output.xml -fxml-start=myClass,foo::bar input.cxx

The argument to -fxml-start is a comma-separated list of start
locations.  Each location can be a qualified name starting at the
global namespace.  If the option is not given, the whole global
namespace is dumped.  No template or function arguments are allowed.
To gain exact control over the start locations, one can always write a
dummy function whose arguments are the types to be dumped.  Specifying
the name of this function with -fxml-start will begin the dump there.

The new implementation has not been extensively tested, so I suggest
configuring the patched GCC with --enable-checking to get errors
instead of seg-faults if something goes wrong.

For anyone who tries this out, I welcome comments on the new dump
format.  It is not written in stone.  You will probably notice that
the output is significantly smaller, especially if the -fxml-start
option is used.  The output is less human-readable (in my opinion),
but is much better for parsing and for use by a program.

-Brad