[Lldb-commits] [PATCH] D30249: Clear expression when breakpoint location becomes unresolved

Jim Ingham via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Thu Feb 23 12:01:32 PST 2017

jingham added a comment.

Sorry, I sent a reply but did it by replying to the e-mail version of the patch, and the mail server choked on it for reasons that aren't clear to me...

Greg was most likely thinking that BreakpointLocation had a "Clear" method like the Target and Process, which we can call when WE know we're done with something, but we can't tell when it will actually get destroyed.  BreakpointLocation hasn't needed such a thing.  In fact, if you wanted to fix this by adding a Clear method and removing the expression there, that would be fine too.  In the process & target case we have to know that we've cleared them, but since you're only throwing away a cache, you wouldn't need to do any extra work for BreakpointLocations.

However, solving the reference loop with a weak pointer in SBBreakpoint is fine as well.  The targets keep the breakpoints alive as long as the target exists, and about the only  sensible thing you can do with a breakpoint after it's target is gone, is print it's ID in an error "Hey, I tried to do something with breakpoint 1 but it didn't work because it's target was gone".  Now you will either have to keep that info redundantly on the side or say <UNKNOWN> rather than "1".

That doesn't seems worth keeping the breakpoint alive.


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