crash on _read that yields a local binding

[tayloraswift]

Description

this crashes the 5.10 compiler

Reproduction

var last:String
{
    _read
    {
        let x:String = ""
        yield x
    }
}

Stack dump

error: compile command failed due to signal 6 (use -v to see invocation)
swift-frontend: /home/ec2-user/swift/lib/SILGen/SILGenLValue.cpp:3332: void swift::Lowering::LValue::addNonMemberVarComponent(SILGenFunction &, SILLocation, VarDecl *, SubstitutionMap, LValueOptions, SGFAccessKind, AccessStrategy, CanType, llvm::Optional<ActorIsolation>)::NonMemberVarAccessEmitter::emitUsingStorage(LValueTypeData): Assertion `address.isLValue() && "Must have a physical copyable lvalue decl ref that " "evaluates to an address"' failed.
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.      Program arguments: /usr/bin/swift-frontend -frontend -c -primary-file crash5.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -color-diagnostics -new-driver-path /usr/bin/swift-driver -empty-abi-descriptor -resource-dir /usr/lib/swift -module-name crash5 -plugin-path /usr/lib/swift/host/plugins -plugin-path /usr/local/lib/swift/host/plugins -o /tmp/TemporaryDirectory.5OuXDQ/crash5-1.o
1.      Swift version 5.10-dev (LLVM dbfaba0078e9380, Swift 63c8b551eb2f613)
2.      Compiling with the current language version
3.      While evaluating request ASTLoweringRequest(Lowering AST to SIL for file "crash5.swift")
4.      While silgen emitFunction SIL function "@$s6crash54lastSSvr".
 for read for last (at crash5.swift:1:5)
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
/usr/bin/swift-frontend(+0x72e33f4)[0x55f1f34993f4]
/usr/bin/swift-frontend(+0x72e10ce)[0x55f1f34970ce]
/usr/bin/swift-frontend(+0x72e3768)[0x55f1f3499768]
/lib64/libc.so.6(+0x54dd0)[0x7f14760a1dd0]
/lib64/libc.so.6(+0xa153c)[0x7f14760ee53c]
/lib64/libc.so.6(raise+0x16)[0x7f14760a1d26]
/lib64/libc.so.6(abort+0xd3)[0x7f14760757f3]
/lib64/libc.so.6(+0x2871b)[0x7f147607571b]
/lib64/libc.so.6(+0x4dcc6)[0x7f147609acc6]
/usr/bin/swift-frontend(+0x158316b)[0x55f1ed73916b]
/usr/bin/swift-frontend(+0x15843e2)[0x55f1ed73a3e2]
/usr/bin/swift-frontend(+0x1584f29)[0x55f1ed73af29]
/usr/bin/swift-frontend(+0x1580be2)[0x55f1ed736be2]
/usr/bin/swift-frontend(+0x158091f)[0x55f1ed73691f]
/usr/bin/swift-frontend(+0x1628822)[0x55f1ed7de822]
/usr/bin/swift-frontend(+0x1624b3f)[0x55f1ed7dab3f]
/usr/bin/swift-frontend(+0x16116b9)[0x55f1ed7c76b9]
/usr/bin/swift-frontend(+0x1611211)[0x55f1ed7c7211]
/usr/bin/swift-frontend(+0x15d800c)[0x55f1ed78e00c]
/usr/bin/swift-frontend(+0x15d9427)[0x55f1ed78f427]
/usr/bin/swift-frontend(+0x15d7c9d)[0x55f1ed78dc9d]
/usr/bin/swift-frontend(+0x156d9db)[0x55f1ed7239db]
/usr/bin/swift-frontend(+0x14f3c9e)[0x55f1ed6a9c9e]
/usr/bin/swift-frontend(+0x14f4cff)[0x55f1ed6aacff]
/usr/bin/swift-frontend(+0x14f2325)[0x55f1ed6a8325]
/usr/bin/swift-frontend(+0x27f619a)[0x55f1ee9ac19a]
/usr/bin/swift-frontend(+0x14f2153)[0x55f1ed6a8153]
/usr/bin/swift-frontend(+0x14f7f97)[0x55f1ed6adf97]
/usr/bin/swift-frontend(+0x15d75bb)[0x55f1ed78d5bb]
/usr/bin/swift-frontend(+0x14fb1e3)[0x55f1ed6b11e3]
/usr/bin/swift-frontend(+0x14f8db8)[0x55f1ed6aedb8]
/usr/bin/swift-frontend(+0xe122c6)[0x55f1ecfc82c6]
/usr/bin/swift-frontend(+0xe284aa)[0x55f1ecfde4aa]
/usr/bin/swift-frontend(+0xe15dcb)[0x55f1ecfcbdcb]
/usr/bin/swift-frontend(+0xe14533)[0x55f1ecfca533]
/usr/bin/swift-frontend(+0xcc2da3)[0x55f1ece78da3]
/lib64/libc.so.6(+0x3feb0)[0x7f147608ceb0]
/lib64/libc.so.6(__libc_start_main+0x80)[0x7f147608cf60]
/usr/bin/swift-frontend(+0xcc1d85)[0x55f1ece77d85]
error: fatalError

Expected behavior

it compiles fine in 5.9

Environment

Swift version 5.10-dev (LLVM dbfaba0078e9380, Swift 63c8b55)
Target: x86_64-unknown-linux-gnu

Additional information

it also crashes the 5.10 compiler on SwiftFiddle

[tayloraswift]

it also crashes on main

[jckarter]

#71630 should fix it. You mentioned in https://forums.swift.org/t/pitch-piecewise-consumption-of-noncopyable-values/70045/4 that you were also seeing this problem with _modify coroutines, but those would not be affected by this same code path, and I wasn't able to reproduce a crash with a similar _modify coroutine yourself. Do you have an example of the crash you're seeing with a _modify coroutine?

[tayloraswift]

i don’t recall seeing this specifically with _modifys, only in the vicinity of yields on local bindings, and i extrapolated from that to all uses of yield. i was also not able to produce a crash in _modify by fuzzing the test program, but i don’t know yet if there are no such instances in our code base, because we do have a number of _modifys that yield local bindings and i am still working on getting the projects to build again due to other 5.10 compiler crashes.

in the absence of a specific reproducer, i think it’s reasonable to assume it only affects _reads. thanks for the fix!