Accessing isolation of `sending @escaping @isolated(any)` parameter crashes compiler

[jamieQ]

Description

the given example crashes. removing either of the sending or @escaping parameter attributes seems to prevent the crash.

Reproduction

func example(
    _ operation: sending @escaping @isolated(any) () async -> Void
) {
    _ = operation.isolation
}

Stack dump

Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/swift-6.1/usr/bin/swift-frontend -frontend -emit-silgen -primary-file <source> -target x86_64-unknown-linux-gnu -disable-objc-interop -g -debug-info-format=dwarf -dwarf-version=4 -swift-version 6 -empty-abi-descriptor -resource-dir /opt/compiler-explorer/swift-6.1/usr/lib/swift -enable-anonymous-context-mangled-names -file-compilation-dir /app -Xllvm --x86-asm-syntax=intel -module-name output -in-process-plugin-server-path /opt/compiler-explorer/swift-6.1/usr/lib/swift/host/libSwiftInProcPluginServer.so -plugin-path /opt/compiler-explorer/swift-6.1/usr/lib/swift/host/plugins -plugin-path /opt/compiler-explorer/swift-6.1/usr/local/lib/swift/host/plugins -o /app/output.s
1.	Swift version 6.1 (swift-6.1-RELEASE)
2.	Compiling with the current language version
3.	While evaluating request ASTLoweringRequest(Lowering AST to SIL for file "<source>")
4.	While silgen emitFunction SIL function "@$s6output7exampleyyyyYaYAcnF".
 for 'example(_:)' (at <source>:1:1)
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):
0  swift-frontend 0x0000593f6863d7d8
1  swift-frontend 0x0000593f6863b57e
2  swift-frontend 0x0000593f6863de7d
3  libc.so.6      0x000075ad9ec42520
4  swift-frontend 0x0000593f633e2399

*** Signal 5: Backtracing from 0x593f633e239a... done ***

*** Program crashed: System trap at 0x0000000000000000 ***

Thread 0 "swift-frontend" crashed:

0  0x0000593f633e239a (anonymous namespace)::TypeClassifierBase<(anonymous namespace)::LowerType, swift::Lowering::TypeLowering*>::visit(swift::CanType, swift::Lowering::AbstractionPattern, swift::Lowering::IsTypeExpansionSensitive_t) + 1210 in swift-frontend


Registers:

rax 0x0000593f633e2398  cc cc cc cc cc cc cc cc 55 41 57 41 56 41 55 41  ÌÌÌÌÌÌÌÌUAWAVAUA
rdx 0x0000593f9bbc3278  50 2a 8e 9b 3f 59 00 00 36 20 00 08 00 00 00 00  P*··?Y··6 ······
rcx 0x0000593f68ffab78  34 76 3e fa 20 78 3e fa 20 78 3e fa 48 76 3e fa  4v>ú x>ú x>úHv>ú
rbx 0x0000000000000000  0
rsi 0x00007fff9dbead78  80 f3 0d 98 ad 75 00 00 18 f4 0d 98 ad 75 00 00  ·ó··­u···ô··­u··
rdi 0x00007fff9dbeadd0  00 2c 8e 9b 3f 59 00 00 78 32 bc 9b 3f 59 00 00  ·,··?Y··x2¼·?Y··
rbp 0x0000000000000000  0
rsp 0x00007fff9dbead70  70 af be 9d ff 7f 00 00 80 f3 0d 98 ad 75 00 00  p¯¾·ÿ····ó··­u··
 r8 0x0000000000000009  9
 r9 0x0000593f9b8e2c00  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ················
r10 0x0000593f9bbc3278  50 2a 8e 9b 3f 59 00 00 36 20 00 08 00 00 00 00  P*··?Y··6 ······
r11 0x0000000000000000  0
r12 0x000075ad980df380  70 b7 bf 9b 3f 59 00 00 30 c6 bf 9b 3f 59 00 00  p·¿·?Y··0Æ¿·?Y··
r13 0x0000593f9bbc3278  50 2a 8e 9b 3f 59 00 00 36 20 00 08 00 00 00 00  P*··?Y··6 ······
r14 0x00007fff9dbeae18  80 f3 0d 98 ad 75 00 00 01 00 00 00 00 00 00 00  ·ó··­u··········
r15 0x00007fff9dbeadd0  00 2c 8e 9b 3f 59 00 00 78 32 bc 9b 3f 59 00 00  ·,··?Y··x2¼·?Y··
rip 0x0000593f633e239a  cc cc cc cc cc cc 55 41 57 41 56 41 55 41 54 53  ÌÌÌÌÌÌUAWAVAUATS

rflags 0x0000000000000203  CF

cs 0x0033  fs 0x0000  gs 0x0000


Images (28 omitted):

0x0000593f60c20000–0x0000593f6870cc00 0bcdc9344aa7f288f7fabe97915174f9f4d697b1 swift-frontend /opt/compiler-explorer/swift-6.1/usr/bin/swift-frontend

Backtrace took 0.42s

Program terminated with signal: SIGTRAP
Compiler returned: 133

Expected behavior

appropriate code should be generated

Environment

Swift version 6.1 (swift-6.1-RELEASE)
Target: x86_64-unknown-linux-gnu

Additional information

compiler explorer example: https://swift.godbolt.org/z/5hfhqvanM

per compiler explorer, appears to affect 6.0, 6.1, 6.2-dev, & main

[jamieQ]

looks like the issue is that operation in the operation.isolation expression receives the type @lvalue @isolated(any) () async -> Void during constraint generation/solving, which then trips an assertion during SILGen in visitExtractFunctionIsolationExpr requiring it not be a l-value. in addition to removing the sending/@escaping attributes, the following also work around the issue:

// rebind to a local variable:
let operation = operation
_ = operation.isolation

// strip `@lvalue`-ness with an explicit cast before accessing the property
_ = (operation as @isolated(any) () async -> Void).isolation

cc @xedin do you have any tips where to look for the code responsible for producing the @lvalue during type checking? or any ideas why the presence of both sending @escaping seems to be somehow responsible for this behavior?