Date: Thu, 23 Jul 2015 11:10:57 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-standards@FreeBSD.org Subject: [Bug 201784] [libcxxrt] C++ dynamic_cast does not recognize same types across dynamically loaded modules when downcasting Message-ID: <bug-201784-15-sCwKm8yasm@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-201784-15@https.bugs.freebsd.org/bugzilla/> References: <bug-201784-15@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=201784 David Chisnall <theraven@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |theraven@FreeBSD.org --- Comment #3 from David Chisnall <theraven@FreeBSD.org> --- This is a known issue (I can't find the closed bug report for it at the moment). If you don't link with -Wl,-export-dynamic, then the RTTI symbols will not be merged. This then means that the pointer comparison in libcxxrt will fail. The work-around that libsupc++ implements replaces the pointer comparison with string comparison. This adds a noticeable performance hit in all dynamic_casts. We decided not to impose a performance hit on all C++ programs just to benefit people who can pass different linker flags to avoid a bug. -- You are receiving this mail because: You are the assignee for the bug.
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