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[SR-1722] Recursive enum (via Array as indirection) compiles but causes runtime deadlock. #44331

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regexident opened this issue Jun 9, 2016 · 1 comment
Closed

[SR-1722] Recursive enum (via Array as indirection) compiles but causes runtime deadlock. #44331

regexident opened this issue Jun 9, 2016 · 1 comment
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software run-time crash Bug → crash: Swift code crashed during execution runtime The Swift Runtime

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@regexident
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Previous ID SR-1722
Radar None
Original Reporter @regexident
Type Bug
Status Resolved
Resolution Duplicate
Environment

OS X El Capitan.
Shouldn't matter though.

Additional Detail from JIRA
Votes 0
Component/s Compiler
Labels Bug, RunTimeCrash, Runtime
Assignee None
Priority Medium

md5: 99032780a3fad302fa3f0e9d99fddca8

duplicates:

  • SR-263 Implement a general solution to prevent deadlocks when generic types rely on their own metadata recursively

Issue Description:

This code compiles without warnings/errors but deadlocks:

enum Tree<Value> {
    case Leaf(Value)
    case Branch(Value, [Tree<Value>])
}

let tree = Tree<Int>.Branch(42, [.Leaf(42)])
print(tree)

Pausing the program returns the following stack trace:

#&#8203;0  0x00007fff99c59de6 in __psynch_mutexwait ()
#&#8203;1  0x00007fff95bcbe4a in _pthread_mutex_lock_wait ()
#&#8203;2  0x00007fff88318f6d in std::__1::mutex::lock() ()
#&#8203;3  0x000000010257c801 in swift::MetadataCache<(anonymous namespace)::GenericCacheEntry>::addMetadataEntry(swift::EntryRef<(anonymous namespace)::GenericCacheEntry>, ConcurrentList<swift::MetadataCache<(anonymous namespace)::GenericCacheEntry>::EntryPair>&, llvm::function_ref<(anonymous namespace)::GenericCacheEntry* ()>) ()
#&#8203;4  0x0000000102579739 in swift_getGenericMetadata2 ()
#&#8203;5  0x00000001023102f1 in ___lldb_unnamed_function23$$Tree ()
#&#8203;6  0x000000010257c9b8 in (anonymous namespace)::GenericCacheEntry* llvm::function_ref<(anonymous namespace)::GenericCacheEntry* ()>::callback_fn<swift_getGenericMetadata::$_1>(long) ()
#&#8203;7  0x000000010257c851 in swift::MetadataCache<(anonymous namespace)::GenericCacheEntry>::addMetadataEntry(swift::EntryRef<(anonymous namespace)::GenericCacheEntry>, ConcurrentList<swift::MetadataCache<(anonymous namespace)::GenericCacheEntry>::EntryPair>&, llvm::function_ref<(anonymous namespace)::GenericCacheEntry* ()>) ()
#&#8203;8  0x0000000102579739 in swift_getGenericMetadata2 ()
#&#8203;9  0x000000010231dbdb in static …(…) -> Tree<Int> at …/Tree.swift:167

Replacing "enum" with "indirect enum" fixes the problem.

I have the feeling that this should either work (preferred, obviously) or not compile in the first place.
@regexident
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With …

Apple Swift version 4.0 (swiftlang-900.0.54.11 clang-900.0.31)
Target: x86_64-apple-macosx10.9

… this code now fails to compile with …

Terminated due to signal: ABORT TRAP (6)
GenericCache(0x101e4a0e8): cyclic metadata dependency detected, aborting

…which still isn't a particularly useful and human-friendly error message, but at least it doesn't compile anymore.

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@AnthonyLatsis AnthonyLatsis added the crash Bug: A crash, i.e., an abnormal termination of software label Dec 12, 2022
This issue was closed.
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. compiler The Swift compiler in itself crash Bug: A crash, i.e., an abnormal termination of software run-time crash Bug → crash: Swift code crashed during execution runtime The Swift Runtime
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@regexident @AnthonyLatsis