ayzhao added inline comments.
================ Comment at: clang/lib/Sema/SemaInit.cpp:5380 + } + InitExprs.push_back(ER.get()); + } ---------------- ilya-biryukov wrote: > ayzhao wrote: > > ayzhao wrote: > > > So the libc++ test compile failures are due to this line. > > > > > > One example of a failing unit test is > > > [range.take.while/ctor.view.pass](https://github.com/llvm/llvm-project/blob/main/libcxx/test/std/ranges/range.adaptors/range.take.while/ctor.view.pass.cpp). > > > Clang calls this function twice in `TreeTransform.h` - once with > > > `VerifyOnly` set to `true`, once with it set to `false`. > > > > > > For some reason, when this function tries to value-initialize the member > > > `MoveOnly mo` in `View`, `Seq.Failed()` returns false after > > > `TryValueInitialization(...)`, but the resulting `ExprResult` is > > > `nullptr`, causing the segfault we see when we push `nullptr` to > > > `InitExprs` and pass `InitExprs` to the constructor of > > > `CXXParenListInitExpr`. One way to be fix this is to move the line > > > `ExprResult ER = Seq.Perform(...)` out of the `if (!VerifyOnly)` block > > > and check for `ER.isInvalid()` instead of `Seq.Failed()`, but that > > > results in test failures due to excess diagnostic messages in > > > `Seq.Perform(...)` > > > > > > I'm still looking into this, but if anyone has any ideas, they would be > > > very welcome. > > > > > > To repro the buildbot failures, just build clang with this patch, and > > > then in a separate build directory, build the target `check-cxx` using > > > the previously built clang. > > I was able to get the above workaround to pass the test by clearing the > > diagnostics after calling `Seq.Perform(...)`. > > > > IMO, this should be OK for now, but I'm open to better ideas if anyone has > > any. > Clearing all the diagnostics is a nuclear options and definitely seems off > here. We should not call `Perform()` when `VerifyOnly` is `true` to avoid > producing the diagnostics in the first place. > > It's fine for the call with `VerifyOnly = true` to return no errors and later > produce diagnostics with `VerifyOnly = false`, I believe this is what > `InitListChecker` is already doing. > I have been playing around with the old version of the code, but couldn't fix > it fully. I do have a small example that breaks, we should add it to the test > and it should also be easier to understand what's going on: > > ``` > struct MoveOnly > { > MoveOnly(int data = 1); > MoveOnly(const MoveOnly&) = delete; > MoveOnly(MoveOnly&&) = default; > }; > > struct View { > int a; > MoveOnly mo; > }; > > void test() { > View{0}; > View(0); // should work, but crashes and produces invalid diagnostics. > } > ``` > > In general, my approach would be to try mimicing what `InitListChecker` is > doing as much as possible, trimming all the unnecessary complexity that > braced-init-lists entail. > Hope it's helpful. So it looks like all I had to do was remove the call to `TryValueInitialization(...)` and just check for `Seq.Failed()`. This is also what we do in `InitListChecker`. The `check-cxx` target appears to work for me locally, so fingers crossed that the build passes. > I do have a small example that breaks, we should add it to the test and it > should also be easier to understand what's going on: Done. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D129531/new/ https://reviews.llvm.org/D129531 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
