187744 2018-07-17 18:36:06 -0700 Switch CMake ports back to C++ 14 2018-07-19 03:18:29 -0700 1 1 1 Unclassified WebKit WebCore Misc. Other PC Linux RESOLVED FIXED https://bugs.webkit.org/show_bug.cgi?id=187669 InRadar P2 Normal --- 1 mcatanzaro mcatanzaro bugs-noreply calvaris commit-queue jfbastien mcatanzaro rniwa webkit-bug-importer oldest_to_newest 1442878 0 mcatanzaro 2018-07-17 18:36:06 -0700 A few months ago, we switched CMake ports from C++ 14 to C++ 17. There have been some problems. Notably, we have not yet addressed the situation with std::optional. Misuse of std::optional that causes a runtime crash on GTK/WPE, when built with GCC 7 or 8, is still just a debug assert on Mac, bug #187669. This has been an ongoing problem for several months. I propose switching back to C++ 14 until this is resolved. It's also worth pointing out that stuck supporting the GCC 5 libstdc++ for the foreseeable future, even though we require GCC 6 for actually compiling WebKit. This severely limits the benefit of using C++ 17 since we can't rely on any of the standard library features. 1442890 1 mcatanzaro 2018-07-17 19:18:54 -0700 This turned out to be easy. It seems we are not using any C++ 17 features anywhere in the codebase. I guess it's not too surprising, since the XCode build is apparently still on C++ 14. 1442891 2 345218 mcatanzaro 2018-07-17 19:22:31 -0700 Created attachment 345218 Patch 1442995 3 345218 commit-queue 2018-07-18 07:43:57 -0700 Comment on attachment 345218 Patch Clearing flags on attachment: 345218 Committed r233912: <https://trac.webkit.org/changeset/233912> 1442996 4 commit-queue 2018-07-18 07:43:59 -0700 All reviewed patches have been landed. Closing bug. 1442997 5 webkit-bug-importer 2018-07-18 07:44:17 -0700 <rdar://problem/42334051> 1443006 6 jfbastien 2018-07-18 08:00:47 -0700 (In reply to Michael Catanzaro from comment #0) > A few months ago, we switched CMake ports from C++ 14 to C++ 17. There have > been some problems. Notably, we have not yet addressed the situation with > std::optional. Misuse of std::optional that causes a runtime crash on > GTK/WPE, when built with GCC 7 or 8, is still just a debug assert on Mac, > bug #187669. This has been an ongoing problem for several months. I propose > switching back to C++ 14 until this is resolved. What are the associated bugs for this? > It's also worth pointing out that stuck supporting the GCC 5 libstdc++ for > the foreseeable future, even though we require GCC 6 for actually compiling > WebKit. This severely limits the benefit of using C++ 17 since we can't rely > on any of the standard library features. What is the issue precisely? You can compiler with a newer libstdc++ and use the ABI compatibility macro to support older distros. 1443018 7 mcatanzaro 2018-07-18 08:56:30 -0700 (In reply to JF Bastien from comment #6) > (In reply to Michael Catanzaro from comment #0) > > A few months ago, we switched CMake ports from C++ 14 to C++ 17. There have > > been some problems. Notably, we have not yet addressed the situation with > > std::optional. Misuse of std::optional that causes a runtime crash on > > GTK/WPE, when built with GCC 7 or 8, is still just a debug assert on Mac, > > bug #187669. This has been an ongoing problem for several months. I propose > > switching back to C++ 14 until this is resolved. > > What are the associated bugs for this? Currently bug #187669, but for motivation, see also: bug #186536, bug #185159, bug #187672, bug #186189, bug #186535, bug #186752, bug #186753, bug #187139, bug #187145, bug #187243, bug #187382. I think we can switch back to C++ 17 when bug #187669 is fixed, but I don't expect that to happen soon. Also, it'd be good to switch XCode at the same time. > What is the issue precisely? You can compiler with a newer libstdc++ and use > the ABI compatibility macro to support older distros. That's what I had hoped, but sadly, the application will still be linked to the older system libstdc++, and apparently you can't static link to a newer libstdc++ and also dynamic link to the system version at the same time. At least, I've never seen anyone successfully accomplish this. So we have to treat libstdc++ as a runtime dependency. Under our current dependencies policy, we'd drop support for libstdc++ for GCC 5 one year after bumping the compiler requirement, i.e. April next year. But that will screw over Ubuntu 16.04, the first version of Ubuntu to provide security support for WebKit, which is supposed to be supported another two years after that. So we'll have to figure out what we are going to do here. 345218 2018-07-17 19:22:31 -0700 2018-07-18 07:43:57 -0700 Patch bug-187744-20180717212231.patch text/plain 3687 mcatanzaro U3VidmVyc2lvbiBSZXZpc2lvbjogMjMzODc5CmRpZmYgLS1naXQgYS9Tb3VyY2UvV1RGL0NoYW5n ZUxvZyBiL1NvdXJjZS9XVEYvQ2hhbmdlTG9nCmluZGV4IDA2NDgwN2UzYjgyZThjY2JlYzA3MDJm Nzg5YmY1ODdhODdhNmFjNjQuLmExYzUxNzA5MmVhZTEyMGJmNDY3ZDA1ZDNhYjJmZTU3NzdjZjQ4 NzQgMTAwNjQ0Ci0tLSBhL1NvdXJjZS9XVEYvQ2hhbmdlTG9nCisrKyBiL1NvdXJjZS9XVEYvQ2hh bmdlTG9nCkBAIC0xLDMgKzEsMTUgQEAKKzIwMTgtMDctMTcgIE1pY2hhZWwgQ2F0YW56YXJvICA8 bWNhdGFuemFyb0BpZ2FsaWEuY29tPgorCisgICAgICAgIFN3aXRjaCBDTWFrZSBwb3J0cyBiYWNr IHRvIEMrKyAxNAorICAgICAgICBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9zaG93X2J1Zy5jZ2k/ aWQ9MTg3NzQ0CisKKyAgICAgICAgUmV2aWV3ZWQgYnkgTk9CT0RZIChPT1BTISkuCisKKyAgICAg ICAgQWx3YXlzIHVzZSBXVEYncyBpbnRlcm5hbCBzdGQ6Om9wdGlvbmFsIGltcGxlbWVudGF0aW9u LCBzaW5jZSBzdGQ6Om9wdGlvbmFsIGlzIG5vdCBwYXJ0IG9mCisgICAgICAgIEMrKyAxNC4KKwor 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