`null pointer dereference` crash on armeabi-v7a about swift-everywhere-toolchain

[vgorloff]

Nice. I saw the change in canPrespecializeTarget, but wasn't sure that it will address this issue.
Thank you! @buttaface

@michaelknoch Seems you can try toolchain release based on Swift 5.4.2.

[vgorloff]

The call /lib/arm/libswiftCore.so (swift_getCanonicalPrespecializedGenericMetadata+20) seems corresponds to this line: https://github.com/apple/swift/blob/swift-5.4.1-RELEASE/stdlib/public/runtime/Metadata.cpp#L805

The call /lib/arm/libswiftCore.so (swift_once+44) seems corresponds to this line: https://github.com/apple/swift/blob/swift-5.4.1-RELEASE/stdlib/public/runtime/Metadata.cpp#L731

The call /lib/arm/libc++_shared.so (std::__ndk1::__call_once(unsigned long volatile&, void*, void (*)(void*))+74) seems corresponds to this line: https://github.com/apple/swift/blob/swift-5.4.1-RELEASE/stdlib/public/runtime/Once.cpp#L65

The remaining two lines /lib/arm/libswiftCore.so seems something what executed inside swift_once:

swift_once(
      token,
      [](void *uncastDescription) {
        auto *description = (const TypeContextDescriptor *)uncastDescription;
        _cacheCanonicalSpecializedMetadata(description);
      },
      (void *)description)

Maybe like something wrong with _cacheCanonicalSpecializedMetadata(description) call. Or maybe with call to std::__ndk1::__call_once.

Seems you need a debug build of libswiftCore to see more symbols.

[finagolfin]

This is a known issue with Swift 5.4, apple/swift#36658, that was fixed with Swift 5.4.2, which I see Vlad just released.

[michaelknoch]

seems to work, the crash does not happen when using the 5.4.2 release. thanks @buttaface @vgorloff !