On Mon, Aug 24, 2015 at 7:42 PM, Richard Smith <rich...@metafoo.co.uk> wrote: > On Mon, Aug 24, 2015 at 3:36 PM, Aaron Ballman <aaron.ball...@gmail.com> > wrote: >> >> On Mon, Aug 24, 2015 at 6:29 PM, Richard Smith <rich...@metafoo.co.uk> >> wrote: >> > On Mon, Aug 24, 2015 at 3:23 PM, Aaron Ballman <aaron.ball...@gmail.com> >> > wrote: >> >> >> >> aaron.ballman created this revision. >> >> aaron.ballman added reviewers: alexfh, rsmith. >> >> aaron.ballman added a subscriber: cfe-commits. >> >> >> >> Per [except.handle]p10, the handler for a constructor or destructor >> >> function-try-block cannot refer to a non-static member of the object >> >> under >> >> construction. This patch adds a new clang-tidy check that warns the >> >> user >> >> when they've hit this undefined behavior. >> >> >> >> Due to how infrequent function-try-blocks appear on constructors and >> >> destructors in the wild compared to how often member expressions are >> >> encountered, I felt this was more appropriate as a clang-tidy check >> >> than as >> >> a semantic warning. I was concerned with efficiency of checking whether >> >> an >> >> arbitrary member expression was referring to the object under >> >> construction/destruction within the function-try-block catch handler >> >> scope. >> > >> > >> > Seems like this would be very cheap to check in the case where the >> > object >> > expression is an implicit or explicit CXXThisExpr. It'd be good to have >> > a >> > frontend warning for that case. >> >> Are you thinking the check would likely in BuildMemberReferenceExpr() >> and I would just have to look at the current scope to determine >> whether it's a function-try-block catch handler? > > > Yes, somewhere around there. You might need to wire a Scope* though a couple > of layers though. > >> >> When I looked into >> doing a frontend warning for this, I seemed to struggle with figuring >> out specifically that I was in the catch handler of a >> function-try-block of a constructor or destructor. > > > Looks like there's no better method than walking up the Scope stack until > you hit a scope with the FnTryCatchScope flag (or leave the function), > currently.
That only tells you that you're in a function-try-block, not that you're within the handler of a function-try-block, doesn't it? So to implement this, it seems like I'd have to: 1) Thread a Scope * through to BuildMemberReferenceExpr() 2) Update the Scope class to have both FnTryScope, FnCatchScope, and FnTryCatchScope (that's a bitwise OR of FnTryScope and FnCatchScope) 3) Update the parser to create the proper Scope type for a function-try-block's handler 4) Implement the actual warning I *think* that should about cover it. ~Aaron _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
