[Patch/RFC] link_name attribute to alter the mangling of class types

[Doug Gregor <dgregor at apple dot com>]

This patch adds a new type attribute for the C++ front end called 
link_name. It allows classes to alter their name during name mangling, 
so that the name used in the C++ source can appear differently in the 
output. Here's a short example:

  class __attribute__((__link_name__("bar"))) foo {};
  void do_it(const foo&) {}

The do_it function mangles to the name "_Z5do_itRK3bar", because class 
"foo" has a link_name of "bar".

This is the expanded patch mentioned in the second libstdc++ debug mode 
patch. It allows the code compiled with the libstdc++ debug mode to 
coexist with code compiled without the debug mode (a much-requested 
feature!). Testcase, changelog, and documentation included in the 
patch. Tested on i686-pc-linux-gnu and powerpc-apple-darwin with no new 
regressions.

Would this be okay for mainline, if we decide we need it for libstdc++?

	Doug

Attachment: linkname.patch
Description: Binary data