Richard! We need an informed opinion :D On Fri, Sep 11, 2015 at 3:07 PM Aaron Ballman <aa...@aaronballman.com> wrote:
> Ping? > > On Tue, Sep 8, 2015 at 9:26 AM, Manuel Klimek <kli...@google.com> wrote: > > On Tue, Sep 8, 2015 at 3:23 PM Aaron Ballman <aa...@aaronballman.com> > wrote: > >> > >> On Tue, Sep 8, 2015 at 9:18 AM, Manuel Klimek <kli...@google.com> > wrote: > >> > On Tue, Sep 8, 2015 at 2:23 PM Aaron Ballman <aa...@aaronballman.com> > >> > wrote: > >> >> > >> >> On Tue, Sep 8, 2015 at 5:40 AM, Manuel Klimek <kli...@google.com> > >> >> wrote: > >> >> > Yea, we had that discussion a few times, and I can never remember > why > >> >> > we > >> >> > ended up in the state we're in. > >> >> > We definitely had a time where we switched to just using the exact > >> >> > same > >> >> > name > >> >> > as the node's class name for the matchers. > >> >> > I *think* we didn't do it for cxxRecordDecl, because Richard said > >> >> > that's > >> >> > a > >> >> > relic we should get rid of anyway, but I'm not sure. > >> >> > >> >> FWIW, I think the state we're in is the worst of all worlds. It's not > >> >> intuitive that recordDecl() doesn't match a struct in C mode, and as > >> >> it stands, there is no way to match a struct or union declaration in > C > >> >> at all. > >> > > >> > > >> > Agreed. Best intentions. Worst possible outcome. That's software > >> > development > >> > :) > >> > > >> >> > > >> >> > On Fri, Sep 4, 2015 at 8:32 PM Aaron Ballman < > aa...@aaronballman.com> > >> >> > wrote: > >> >> >> > >> >> >> It turns out that the recordDecl() AST matcher doesn't match > >> >> >> RecordDecl objects; instead, it matches CXXRecordDecl objects. > This > >> >> >> is... unfortunate... as it makes writing AST matchers more > >> >> >> complicated > >> >> >> because of having to translate between recordDecl()/CXXRecordDecl. > >> >> >> It > >> >> >> also makes it impossible to match a struct or union declaration > in C > >> >> >> or ObjC. However, given how prevalent recordDecl()'s use is in the > >> >> >> wild (I'm guessing), changing it at this point would be a Bad > Thing. > >> >> >> > >> >> >> For people trying to write AST matchers for languages like C or > >> >> >> ObjC, > >> >> >> I would like to propose adding: > >> >> >> > >> >> >> structDecl() > >> >> >> unionDecl() > >> >> >> tagDecl() > >> >> >> > >> >> >> These will match nicely with the existing enumDecl() AST matcher. > >> >> >> > >> >> >> Additionally, I would like to add cxxRecordDecl() to match > >> >> >> CXXRecordDecl objects. While it duplicates the functionality > exposed > >> >> >> by recordDecl(), it more clearly matches the intention of which > AST > >> >> >> node it corresponds to. > >> >> >> > >> >> >> Finally, I would like to undocument recordDecl() and change our > >> >> >> existing documentation and AST matcher uses to use > >> >> >> cxxRecordDecl/structDecl() instead. Maybe someday we can deprecate > >> >> >> recordDecl() more officially. > >> >> >> > >> >> >> I'm open to other ideas if there are better ways to move forward. > If > >> >> >> you think changing the meaning of recordDecl() is acceptable, I > can > >> >> >> also go that route (though I would still propose adding > unionDecl() > >> >> >> and cxxRecordDecl() in that case). > >> >> > > >> >> > > >> >> > I think changing recordDecl is acceptable. I believe very few tools > >> >> > will > >> >> > actually start doing wrong things because of it. I'd like more > >> >> > opinions > >> >> > first, though :) > >> >> > >> >> I was giving this more thought over the long weekend, and I think you > >> >> may be right. I think changing recordDecl() to mean RecordDecl will > >> >> fix more code than it breaks, so long as we take a holistic approach > >> >> to the change and see which narrowing and traversal matchers we need > >> >> to fix up at the same time. When I tried to think of AST matchers > that > >> >> mean CXXRecordDecl but *not* RecordDecl, they were horribly contrived > >> >> because you usually are matching on additional selection criteria > that > >> >> is specific to C++ (such as hasMethod() or isDerivedFrom()) which > >> >> would cause the match to continue to fail, as expected. Code that > uses > >> >> recordDecl() to mean RecordDecl will suddenly start to match in more > >> >> cases, but that's likely to be a bug fix more than a breaking change. > >> >> To the best of my understanding, the only breaking cases would be > >> >> where you wrote recordDecl(), meant CXXRecordDecl, had no further > >> >> narrowing or traversal matchers, and were compiling in C mode; with > >> >> the result being additional unexpected matches. > >> > > >> > > >> > Ah, there's one thing that can break: the compile can break: > >> > recordDecl(hasMethod(...)) will *not* compile (it'll work in the > dynamic > >> > matchers and fail as you suggest, but the in-C++ DSL does more static > >> > type > >> > checking). > >> > I don't think that's super bad though. > >> > > >> >> > >> >> So perhaps it would make sense to: > >> >> > >> >> 1) Make recordDecl() mean RecordDecl > >> >> 2) Do a comprehensive review of matchers that take a CXXRecordDecl > and > >> >> see if they should instead take a RecordDecl > >> >> 3) Add unionDecl() as a node matcher (or should we add isUnion() and > >> >> isStruct() as narrowing matchers?) > >> >> 4) Add tagDecl() as a node matcher, but not add cxxRecordDecl() > >> > > >> > > >> > Why not add cxxRecordDecl()? I think we need it if we want narrowing > >> > matchers on CXXRecordDecl? > >> > >> If Richard thinks CXXRecordDecl is an anachronism, I figured we didn't > >> want to expose it. Instead, we could make hasMethod (et al) accept a > >> RecordDecl and do the type checking for the caller. Then > >> recordDecl(hasMethod(...)) continues to compile and work, and when > >> hasMethod is given a RecordDecl instead of a CXXRecordDecl, it simply > >> matches nothing. But you bring up a good point about the C++ DSL being > >> a problem still, I hadn't considered that. > > > > > > First I want Richard to confirm that. I have a very bad memory, so I > might > > as well misremember :) > > > >> > >> > >> ~Aaron > >> > >> > > >> >> > >> >> > >> >> ~Aaron > >> >> > >> >> > > >> >> >> > >> >> >> > >> >> >> Thanks! > >> >> >> > >> >> >> ~Aaron >
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