mpgen: Work around c++20 / capnproto 0.8 incompatibility #194
Conversation
|
The following sections might be updated with supplementary metadata relevant to reviewers and maintainers. ReviewsSee the guideline for information on the review process.
If your review is incorrectly listed, please react with 👎 to this comment and the bot will ignore it on the next update. |
|
Updated 151ef65 -> c659685 ( |
| rev = "v${capnprotoVersion}"; | ||
| hash = lib.attrByPath [capnprotoVersion] "" capnprotoHashes; | ||
| }; | ||
| patches = lib.optionals (lib.versionAtLeast capnprotoVersion "0.9.0" && lib.versionOlder capnprotoVersion "0.10.4") [ ./ci/patches/spaceship.patch ]; |
There was a problem hiding this comment.
88d9504: do I read this correctly as: apply patch to versions 0.9.0 <= ... < 0.10.4?
There was a problem hiding this comment.
re: #194 (comment)
88d9504: do I read this correctly as: apply patch to versions 0.9.0 <= ... < 0.10.4?
Yes that's right. These versions of capnproto added some c++20 support which didn't actually work with later compiler versions.
|
utACK 88d9504 |
The kj/string.h header installed by capnproto 0.8 doesn't work well when
compiling with -std=c++20 or later because the reverse StringPtr/char*
comparison function it provides is broken in c++20:
inline bool operator==(const char* a, const StringPtr& b) { return b == a; }
Before C++20 this would implicitly convert `a` to a StringPtr and call the
StringPtr::operator== method. But starting with C++20 it actually calls itself
recursively and either loops forever or crashes.
This problem was fixed upstream by
capnproto/capnproto#1170 in Cap'n Proto 0.9.0. Avoid
the problem here for older versions by just not using the operator. A CI job
testing older versions is added in the next commit to avoid similar breakage in
the future.
The CI job currently just tests old Cap'n Proto versions, but it might be nice to extend in the future to test old compilers & build tools too. Support for versions of Cap'n Proto before 0.7.0 was dropped in bitcoin-core#88 in order to avoid compiler warnings and simplify code. Before that, versions back to 0.5 were supported and are basically still compatible since the Cap'n Proto API hasn't changed and libmultiprocess does not rely on newer features.
30930df build: require CapnProto 0.7.0 or better (Sjors Provoost) Pull request description: Although 1.0.1. is the oldest version currently covered by Bitcoin Core's extensive CI, Debian Bookwork ships 0.9.2 and #194 introduces test coverage for even older versions. 0.7 has been required since #88. The CI run of Sjors/bitcoin#100 @ [3d55222](https://github.com/Sjors/bitcoin/pull/100/checks?sha=3d552223712eed88d17e5ead1ef7d1ba6fd7e89e) previously checked Bitcoin Core CI against 1.0.1 as the minimum. Lowering the minimum further should not be a problem for that CI. ACKs for top commit: ryanofsky: Code review ACK 30930df. Planning to follow up in #194 to actually test minimum version and error if capnproto version detected is affected by CVE-2022-46149 Tree-SHA512: bed5843973c8ff1f0b2bd93efe7169824c2306097efefaace1752efeb06606df765b68b7ef50c07f5d703010c4d1b324099d6780fa0363e126d34ac1307fba1a
Also document minimum Cap'n Proto version in doc/install.md
There was a problem hiding this comment.
Rebased 88d9504 -> dc3ba22 (pr/string.3 -> pr/string.4, compare) on top of #193 and added explicit check for CVE-2022-46149
| rev = "v${capnprotoVersion}"; | ||
| hash = lib.attrByPath [capnprotoVersion] "" capnprotoHashes; | ||
| }; | ||
| patches = lib.optionals (lib.versionAtLeast capnprotoVersion "0.9.0" && lib.versionOlder capnprotoVersion "0.10.4") [ ./ci/patches/spaceship.patch ]; |
There was a problem hiding this comment.
re: #194 (comment)
88d9504: do I read this correctly as: apply patch to versions 0.9.0 <= ... < 0.10.4?
Yes that's right. These versions of capnproto added some c++20 support which didn't actually work with later compiler versions.
|
utACK dc3ba22 Thanks for adding the CVE version check. |
Fix ubuntu 22.04 compatibility issue reported by fanquake in bitcoin/bitcoin#33176 and add CI job to make sure libmultiprocess stays compatible with old versions of Cap'n Proto.
Changes are described in more detail in commit messages.