Attached is an updated patch for clang-tools-extra that does not have my in-progress, not-related-to-any-of-this code in it. ;-)
~Aaron On Wed, Sep 16, 2015 at 4:04 PM, Aaron Ballman <aa...@aaronballman.com> wrote: > Quick ping. I know this is a fairly gigantic patch, but I'm hoping for > a relatively quick review turnaround because of potential merge > conflicts with people doing a fair amount of work on clang-tidy > lately. Everything should be pretty straight-forward (it's all just > renames, no semantic changes intended aside from > recordDecl/cxxRecordDecl and the narrowing matchers. > > ~Aaron > > On Tue, Sep 15, 2015 at 1:32 PM, Aaron Ballman <aa...@aaronballman.com> wrote: >> Here are the complete patches to solve the issues we've discussed: >> >> 1) splits recordDecl into recordDecl and cxxRecordDecl >> 2) adds isStruct, isUnion, isClass to identify what kind of >> recordDecl() you may be looking at >> 3) prefixes all of the node matchers with cxx that should have it >> 4) fixes a similar issue with CUDAKernelCallExpr (the prefix needs to >> be cuda instead of CUDA to distinguish the matcher name from the type >> name). >> 5) updates all of the documentation and code that broke. >> >> One patch is for changes to clang, the other is for changes to >> clang-tools-extra. >> >> ~Aaron >> >> On Mon, Sep 14, 2015 at 5:49 PM, Aaron Ballman <aa...@aaronballman.com> >> wrote: >>> On Mon, Sep 14, 2015 at 5:47 PM, Daniel Jasper <djas...@google.com> wrote: >>>> Btw, I think generating them, potentially into several different headers to >>>> work around the compile time issue isn't such a bad idea. >>> >>> I'm not going to start with this approach, but think it may be worth >>> exploring at some point. ;-) >>> >>> ~Aaron >>> >>>> >>>> On Mon, Sep 14, 2015 at 11:45 PM, Manuel Klimek <kli...@google.com> wrote: >>>>> >>>>> Feel free to rename the AST nodes :) >>>>> >>>>> >>>>> On Mon, Sep 14, 2015, 2:44 PM Daniel Jasper <djas...@google.com> wrote: >>>>>> >>>>>> Ok. I am happy with this then. >>>>>> >>>>>> (Just personally grumpy having to write >>>>>> cxxRecordDecl(has(cxxConstructorDecl(..))) in the future ;-) ). >>>>>> >>>>>> On Mon, Sep 14, 2015 at 11:41 PM, Manuel Klimek <kli...@google.com> >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Mon, Sep 14, 2015 at 2:29 PM Aaron Ballman <aa...@aaronballman.com> >>>>>>> wrote: >>>>>>>> >>>>>>>> On Mon, Sep 14, 2015 at 4:38 PM, Manuel Klimek <kli...@google.com> >>>>>>>> wrote: >>>>>>>> > >>>>>>>> > >>>>>>>> > On Mon, Sep 14, 2015 at 12:26 PM Aaron Ballman >>>>>>>> > <aa...@aaronballman.com> >>>>>>>> > wrote: >>>>>>>> >> >>>>>>>> >> On Mon, Sep 14, 2015 at 2:45 PM, Daniel Jasper <djas...@google.com> >>>>>>>> >> wrote: >>>>>>>> >> > By this point, I see that change might be profitable overall. >>>>>>>> >> > However, >>>>>>>> >> > lets >>>>>>>> >> > completely map this out. Changing just cxxRecordDecl() can >>>>>>>> >> > actually >>>>>>>> >> > increase >>>>>>>> >> > confusion in other areas. Right now, not a single AST matcher has >>>>>>>> >> > the >>>>>>>> >> > cxx >>>>>>>> >> > prefix (although a total of 28 stand for the corresponding CXX.. >>>>>>>> >> > AST >>>>>>>> >> > node). >>>>>>>> >> > This is consistent and people knowing this will never try to write >>>>>>>> >> > cxxConstructExpr(). As soon as people have used cxxRecordDecl(), >>>>>>>> >> > the >>>>>>>> >> > chance >>>>>>>> >> > of them trying cxxConstructExpr() increases. You have spent a long >>>>>>>> >> > time >>>>>>>> >> > figuring out that recordDecl means cxxRecordDecl(), which is one >>>>>>>> >> > datapoint, >>>>>>>> >> > but I am not aware of anyone else having this specific issue. And >>>>>>>> >> > we >>>>>>>> >> > could >>>>>>>> >> > make this less bad with better documentation, I think. >>>>>>>> >> > >>>>>>>> >> > So, for me, the questions are: >>>>>>>> >> > 1) Do we want/need this change? >>>>>>>> >> >>>>>>>> >> We definitely need *a* change because there currently is no way to >>>>>>>> >> match a C struct or union when compiling in C mode. I discovered >>>>>>>> >> this >>>>>>>> >> because I was trying to write a new checker for clang-tidy that >>>>>>>> >> focuses on C code and it would fail to match when compiling in C >>>>>>>> >> mode. >>>>>>>> >> Whether we decide to go with cxxRecordDecl vs recordDecl vs >>>>>>>> >> structDecl >>>>>>>> >> (etc) is less important to me than the ability to write clang-tidy >>>>>>>> >> checks for C code. >>>>>>>> >> >>>>>>>> >> > 2) Do we want to be consistent and change the other 27 matchers as >>>>>>>> >> > well? >>>>>>>> >> >>>>>>>> >> I'm on the fence about this for all the reasons you point out. >>>>>>>> >> >>>>>>>> >> > A fundamental question is whether we want AST matchers to match >>>>>>>> >> > AST >>>>>>>> >> > nodes >>>>>>>> >> > 1:1 or whether they should be an abstraction from some >>>>>>>> >> > implementation >>>>>>>> >> > details of the AST. >>>>>>>> >> >>>>>>>> >> I absolutely agree that this is a fundamental question. I think a >>>>>>>> >> higher priority fundamental question that goes along with it is: are >>>>>>>> >> we okay with breaking a lot of user code (are these meant to be >>>>>>>> >> stable >>>>>>>> >> APIs like the LLVM C APIs)? If we want these APIs to be stable, that >>>>>>>> >> changes the answer of what kind of mapping we can have. >>>>>>>> > >>>>>>>> > >>>>>>>> > I think the AST matchers are so closely coupled to the AST that it >>>>>>>> > trying to >>>>>>>> > be more stable than the AST doesn't help. Basically all uses of AST >>>>>>>> > matchers >>>>>>>> > do something with the AST nodes afterwards, which will break anyway. >>>>>>>> >>>>>>>> I can get behind that logic. So we're okay with breaking their code >>>>>>>> because there's no way around it -- it's tied to the AST, so users >>>>>>>> cannot rely on the AST APIs remaining the same from release to release >>>>>>>> anyway. >>>>>>> >>>>>>> >>>>>>> We might even *want* the code to break, as the use of the AST node might >>>>>>> now be incorrect on a semantic level. >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> > >>>>>>>> >> >>>>>>>> >> > And this is not an easy question to answer. There are >>>>>>>> >> > many places where we don't follow a strict 1:1 mapping. Mostly >>>>>>>> >> > node >>>>>>>> >> > matchers, but also in traversal matchers, e.g. isDerivedFrom(). >>>>>>>> >> > >>>>>>>> >> > Personally, I'd really hate to have the cxx Prefix everywhere, but >>>>>>>> >> > that's >>>>>>>> >> > just my personal opinion. I would even prefer matchers like >>>>>>>> >> > record() and >>>>>>>> >> > method(), but I think somebody convinced me that that would be a >>>>>>>> >> > very >>>>>>>> >> > bad >>>>>>>> >> > idea ;-). >>>>>>>> >> >>>>>>>> >> My personal opinion is that (1) breaking code is fine, but we should >>>>>>>> >> avoid doing it without very clear benefit, and (2) the mapping >>>>>>>> >> between >>>>>>>> >> AST node identifiers and AST matcher identifiers needs to be >>>>>>>> >> incredibly obvious, but perhaps not slavishly 1:1. If we instead >>>>>>>> >> decide we want a 1:1 mapping, then I think we need to start >>>>>>>> >> seriously >>>>>>>> >> considering auto-generating the AST node (and type) matchers from >>>>>>>> >> tablegen so that the AST nodes *cannot* get out of sync with the AST >>>>>>>> >> matchers, otherwise we'll be right back here again in a few years >>>>>>>> >> when >>>>>>>> >> we modify the name of an AST node. >>>>>>>> > >>>>>>>> > >>>>>>>> > I do think we want to auto-generate the matchers, but I don't think >>>>>>>> > tablegen >>>>>>>> > is the right approach (I think an ast-matcher based tool is ;) >>>>>>>> > That said, auto-generating all the matchers is a) a lot of effort and >>>>>>>> > b) the >>>>>>>> > code-size and compile time of matchers already matters, so it's >>>>>>>> > unclear >>>>>>>> > which ones we would want to generate, especially for traversal >>>>>>>> > matchers :( >>>>>>>> >>>>>>>> Oh, that's an excellent point (I'm talking about (b), I already knew >>>>>>>> (a) was a lot of work). Thank you for pointing that out! >>>>>>>> >>>>>>>> > >>>>>>>> >> >>>>>>>> >> My definition of "incredibly obvious" is: if the AST has a prefixed >>>>>>>> >> and unprefixed version, or two different prefixes, we should mimic >>>>>>>> >> that directly with the matchers. Otherwise, existing AST matchers >>>>>>>> >> without prefix shenanigans can remain as they are, and new AST >>>>>>>> >> matchers should prefix as-required. If we decide we're okay breaking >>>>>>>> >> code, then I don't see a problem with changing ctorInitializer() >>>>>>>> >> into >>>>>>>> >> cxxCtorInitializer() when C adds constructors. ;-) >>>>>>>> > >>>>>>>> > >>>>>>>> > I think the main things is cost for developers who try to write >>>>>>>> > matchers and >>>>>>>> > work from the -ast-dump. Figuring out that there *is* a matcher with >>>>>>>> > an >>>>>>>> > unprefixed node can take a while. >>>>>>>> >>>>>>>> Hmm, yes, but "take a while" should be relatively short, I would >>>>>>>> think. In that use-case, the user does an -ast-dump, sees >>>>>>>> "CXXFrobbleGnasher", they go to the AST matcher reference and they >>>>>>>> search for "CXXFrobberGnasher." The first hit won't be >>>>>>>> cxxFrobbleGnasher, but the entry for frobbleGnasher (which is still >>>>>>>> the first hit when searching from the top of the document due to the >>>>>>>> way we position node matchers) will have a parameter of >>>>>>>> CXXFrobbleGnasher, so they will find still get to the right matcher on >>>>>>>> the first hit. If someone doesn't read the documentation at all, >>>>>>>> they're going to try cxxFrobbleGnasher() and get a compile error/no >>>>>>>> known matcher. Then they'll go look at ASTMatchers.h and figure out >>>>>>>> it's called frobbleGnasher by searching there instead of the >>>>>>>> documentation. >>>>>>> >>>>>>> >>>>>>> The problem is that I've learned that sometimes people try to make >>>>>>> things work in ways that I couldn't even imagine, and they lose more >>>>>>> time >>>>>>> than I could ever imagine them using :) Also, I agree the time is >>>>>>> probably >>>>>>> on average not that large, but we pay it over a long time in the >>>>>>> future, and >>>>>>> it tends to add up. >>>>>>> >>>>>>>> >>>>>>>> That's compared to having the matcher name always be the same as the >>>>>>>> AST node, where the user writes cxxFrobbleGnasher and it just works, >>>>>>>> which is definitely a mark in favor of making everything consistent. I >>>>>>>> just don't think the current approach is too onerous in the case where >>>>>>>> the matcher is at least *provided* for the user with a relatively sane >>>>>>>> name. >>>>>>>> >>>>>>>> >> I should be clear, I'm not opposed to just having a 1:1 mapping. I'm >>>>>>>> >> just not certain the benefits of being strict about that outweigh >>>>>>>> >> the >>>>>>>> >> costs to broken code. cxxCtorInitializer will break someone's code, >>>>>>>> >> but I don't think it adds any clarity to their code, so I don't see >>>>>>>> >> the benefit of forcing the change. >>>>>>>> > >>>>>>>> > Well, I think there's the cost of broken code *once* now, vs. the >>>>>>>> > (smaller) >>>>>>>> > cost for users in all future. >>>>>>>> > I'm still strongly in favor of breaking now, and having a simpler >>>>>>>> > model >>>>>>>> > going forward. >>>>>>>> >>>>>>>> I'm definitely in favor of breaking now in the case of RecordDecl vs >>>>>>>> CXXRecordDecl. I think having recordDecl match CXXRecordDecl is a bug >>>>>>>> given that there's no way to match a RecordDecl. >>>>>>>> >>>>>>>> I would also be totally in favor of being consistent if we were >>>>>>>> starting from scratch. I'm very, very weakly opposed to breaking more >>>>>>>> user's code than we have to in order to get usable matchers because it >>>>>>>> seems gratuitous. Breaking code to get something that works seems >>>>>>>> reasonable. Breaking code that already works just to change the name >>>>>>>> for consistency elsewhere, I'm a bit less keen on. But the fact that >>>>>>>> we already can break user's code at-will because of the reliance on >>>>>>>> the AST nodes makes me think it may be the right approach for the best >>>>>>>> API, since that's what I would want if we were starting from scratch. >>>>>>>> >>>>>>>> Okay, I'm convinced. I think we should rename the type and node >>>>>>>> matchers (not traversal and narrowing matchers) to match the AST node >>>>>>>> names in all cases. We can document the breakage in the release notes, >>>>>>>> but (hopefully) only have to do this dance one time instead of >>>>>>>> spreading the pain out as it happens to eventually get to the same >>>>>>>> place anyway. >>>>>>> >>>>>>> >>>>>>> Yea, people who want more stability do use releases anyway. >>>>>>> >>>>>>>> >>>>>>>> Daniel, is this something you would be okay with? (I'm assuming >>>>>>>> Richard finds it acceptable based on previous comments from Manuel, >>>>>>>> but Richard, feel free to chime in.) >>>>>>> >>>>>>> >>>>>>> Offline conversation with Richard says that he is convinced. >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> ~Aaron >>>>>> >>>>>> >>>>
recordDecl-clang-tools-extra.patch
Description: Binary data
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