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[patch] fix libstdc++/59656

From: Jonathan Wakely <jwakely at redhat dot com>
To: libstdc++ at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
Cc: Kyle Lippincott <spectral at google dot com>, Paul Pluzhnikov <ppluzhnikov at google dot com>
Date: Tue, 28 Jan 2014 10:23:48 +0000
Subject: [patch] fix libstdc++/59656
Authentication-results: sourceware.org; auth=none

This adds new (non-public) constructors to shared_ptr and
__shared_count so that weak_ptr::lock() can be implemented without
exceptions. This allows it to be used with -fno-exceptions and also
avoids the overhead of throwing and catching an exception when the
weak_ptr has expired.

Tested x86_64-linux, committed to trunk.

2014-01-28  Jonathan Wakely  <jwakely@redhat.com>
	    Kyle Lippincott  <spectral@google.com>

PR libstdc++/59656

	* include/bits/shared_ptr.h (shared_ptr): Add new non-throwing
	constructor and grant friendship to weak_ptr.
	(weak_ptr::lock()): Use new constructor.
	* include/bits/shared_ptr_base.h
	(_Sp_counted_base::_M_add_ref_lock_nothrow()): Declare new function
	and define specializations.
	(__shared_count): Add new non-throwing constructor.
	(__shared_ptr): Add new non-throwing constructor and grant friendship
	to __weak_ptr.
	(__weak_ptr::lock()): Use new constructor.
	* testsuite/20_util/shared_ptr/cons/43820_neg.cc: Adjust dg-error.
	* testsuite/20_util/shared_ptr/cons/void_neg.cc: Likewise.

Attachment: patch.txt
Description: Text document

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