Crash compiling Locale_ICU.swift on Windows

[glessard]

Describe the bug
During Windows CI testing, the swift-frontend crashes "While evaluating request ASTLoweringRequest(Lowering AST to SIL for file "C:\source\swift-foundation\Sources\FoundationInternationalization\Locale\Locale_ICU.swift")"

[2025-07-09T20:23:08.285Z] 0.	Program arguments: C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Toolchains\\0.0.0+Asserts\\usr\\bin\\swift-frontend.exe -frontend -c C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\BinaryFloatingPoint.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Calendar\\Calendar_Bridge.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Calendar\\Calendar_ICU.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Calendar\\Calendar_ObjC.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Date+ICU.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Duration+Utils.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\ByteCountFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\Date+AnchoredRelativeFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\Date+ComponentsFormatStyle+Stub.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\Date+IntervalFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\Date+RelativeFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\Date+VerbatimFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\DateFieldSymbol.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\DateFormatString.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\DateFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\DateParseStrategy.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\ICUDateFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\ICUDateIntervalFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Date\\ICURelativeDateFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Duration+Formatting.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Duration+TimeFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Duration+UnitsFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\ICUListFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\ListFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Measurement+FormatStyle+Stub.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\BinaryFloatingPoint+FormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\BinaryInteger+FormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\Decimal+FormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\Decimal+ParseStrategy.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\FloatingPointFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\FloatingPointParseStrategy.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\ICULegacyNumberFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\ICUNumberFormatter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\IntegerFormatStyle.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\IntegerParseStrategy.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\NumberAttributedFormat.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Formatting\\Number\\NumberFormatStyleConfiguration.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+CaseMap.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+Enumeration.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+Enums.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+FieldPositer.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+Foundation.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICU+StringConverter.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\ICU\\ICUPatternGenerator.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Locale\\Locale+Components_ICU.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Locale\\Locale_Bridge.swift -primary-file C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Locale\\Locale_ICU.swift -primary-file C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Locale\\Locale_ObjC.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\Predicate\\LocalizedString.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\RangeExpression.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\String\\KeyPathComparator.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\String\\SortDescriptor.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\String\\String+Locale.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\String\\String+SortComparator.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\String\\StringProtocol+Locale.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\TimeInterval+Utils.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\TimeZone\\TimeZone_Bridge.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\TimeZone\\TimeZone_GMTICU.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\TimeZone\\TimeZone_ICU.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\TimeZone\\TimeZone_ObjC.swift C:\\source\\swift-foundation\\Sources\\FoundationInternationalization\\URLParser+ICU.swift -emit-dependencies-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ICU.d -emit-reference-dependencies-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ICU.swiftdeps -serialize-diagnostics-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ICU.dia -emit-dependencies-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ObjC.d -emit-reference-dependencies-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ObjC.swiftdeps -serialize-diagnostics-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ObjC.dia -target x86_64-unknown-windows-msvc -disable-objc-interop -sdk C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Platforms\\0.0.0\\Windows.platform\\Developer\\SDKs\\Windows.sdk\\ -I C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\Modules -I C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Platforms\\0.0.0\\Windows.platform\\Developer\\Library\\XCTest-0.0.0\\usr\\lib\\swift\\windows -I C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Platforms\\0.0.0\\Windows.platform\\Developer\\Library\\XCTest-0.0.0\\usr\\lib\\swift\\windows\\x86_64 -I C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Platforms\\0.0.0\\Windows.platform\\Developer\\Library\\Testing-0.0.0\\usr\\lib\\swift\\windows -no-color-diagnostics -Xcc -fno-color-diagnostics -enable-testing -g -debug-info-format=dwarf -dwarf-version=4 -module-cache-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\ModuleCache -static -swift-version 5 -Onone -D SWIFT_PACKAGE -D DEBUG -D SWIFT_MODULE_RESOURCE_BUNDLE_UNAVAILABLE -load-plugin-executable C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationMacros-tool.exe#FoundationMacros -enable-experimental-feature AccessLevelOnImport -enable-experimental-feature "AvailabilityMacro=FoundationPreview 6.0.2:macOS 15, iOS 18, tvOS 18, watchOS 11" -enable-experimental-feature "AvailabilityMacro=FoundationPreview 6.1:macOS 15, iOS 18, tvOS 18, watchOS 11" -enable-experimental-feature "AvailabilityMacro=FoundationPreview 6.2:macOS 15, iOS 18, tvOS 18, watchOS 11" -enable-experimental-feature StrictConcurrency -enable-experimental-feature ImportMacroAliases -enable-upcoming-feature InferSendableFromCaptures -enable-upcoming-feature MemberImportVisibility -empty-abi-descriptor -enable-anonymous-context-mangled-names -file-compilation-dir C:\\source\\swift-foundation -Xcc -fmodule-map-file=C:\\source\\swift-foundation\\Sources\\_FoundationCShims\\include\\module.modulemap -Xcc -I -Xcc C:\\source\\swift-foundation\\Sources\\_FoundationCShims\\include -Xcc -fmodule-map-file=C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\_FoundationICU.build\\module.modulemap -Xcc -I -Xcc C:\\source\\swift-foundation\\.build\\checkouts\\swift-foundation-icu\\icuSources\\include -Xcc -D_MT -Xcc -D_DLL -Xcc -Xclang -Xcc --dependent-lib=msvcrt -Xcc -gdwarf -no-auto-bridging-header-chaining -module-name FoundationInternationalization -package-name swift_foundation -in-process-plugin-server-path C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Toolchains\\0.0.0+Asserts\\usr\\bin\\SwiftInProcPluginServer.dll -plugin-path C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Toolchains\\0.0.0+Asserts\\usr\\bin -plugin-path C:\\Users\\ContainerAdministrator\\AppData\\Local\\Programs\\Swift\\Toolchains\\0.0.0+Asserts\\usr\\local\\bin -autolink-library oldnames -autolink-library msvcrt -Xcc -D_MT -Xcc -D_DLL -parse-as-library -o C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ICU.swift.o -o C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\FoundationInternationalization.build\\Locale_ObjC.swift.o -index-store-path C:\\source\\swift-foundation\\.build\\x86_64-unknown-windows-msvc\\debug\\index\\store -index-system-modules

[2025-07-09T20:23:08.285Z] 1.	Swift version 6.2-dev (LLVM 3c4a54b02dd62b7, Swift a40a7be6945a895)

[2025-07-09T20:23:08.285Z] 2.	Compiling with effective version 5.10

[2025-07-09T20:23:08.285Z] 3.	While evaluating request ASTLoweringRequest(Lowering AST to SIL for file "C:\source\swift-foundation\Sources\FoundationInternationalization\Locale\Locale_ICU.swift")

[2025-07-09T20:23:08.285Z] 4.	While silgen emitFunction SIL function "@$sSC16u_vformatMessageys5Int32VSPys4Int8VGSg_SPys6UInt16VGSgACSpyAIGSgACs14CVaListPointerVSgSpySo10UErrorCodeVGSgtcvg".

[2025-07-09T20:23:08.285Z]  for getter for u_vformatMessage (in module '_FoundationICU')

[2025-07-09T20:23:08.285Z] 5.	While emitting reabstraction thunk in SIL function "@$sSPys4Int8VGSgSPys6UInt16VGSgs5Int32VSpyAFGSgAJs14CVaListPointerVSpySo10UErrorCodeVGSgAJIetyyyyyyyd_AdhjljNSgArJIegyyyyyyyd_TR".

[2025-07-09T20:23:08.285Z]  for <<debugloc at "<compiler-generated>":0:0>>Exception Code: 0x80000003

[2025-07-09T20:23:08.285Z]  #0 0x00007ff6cbde5cb5 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x6f15cb5)

[2025-07-09T20:23:08.285Z]  #1 0x00007fff58e0d88d (C:\Windows\System32\ucrtbase.dll+0x6d88d)

[2025-07-09T20:23:08.285Z]  #2 0x00007fff58e0e761 (C:\Windows\System32\ucrtbase.dll+0x6e761)

[2025-07-09T20:23:08.285Z]  #3 0x00007fff58e100c1 (C:\Windows\System32\ucrtbase.dll+0x700c1)

[2025-07-09T20:23:08.285Z]  #4 0x00007fff58e103f1 (C:\Windows\System32\ucrtbase.dll+0x703f1)

[2025-07-09T20:23:08.285Z]  #5 0x00007ff6c5d53c7f (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe83c7f)

[2025-07-09T20:23:08.285Z]  #6 0x00007ff6c5c7ce7e (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdace7e)

[2025-07-09T20:23:08.285Z]  #7 0x00007ff6c5c7a508 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdaa508)

[2025-07-09T20:23:08.285Z]  #8 0x00007ff6c5c7a79d (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdaa79d)

[2025-07-09T20:23:08.285Z]  #9 0x00007ff6c5c604c0 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd904c0)

[2025-07-09T20:23:08.285Z] #10 0x00007ff6c5c6e3fd (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd9e3fd)

[2025-07-09T20:23:08.285Z] #11 0x00007ff6c5c79a57 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xda9a57)

[2025-07-09T20:23:08.285Z] #12 0x00007ff6c5c533e1 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd833e1)

[2025-07-09T20:23:08.285Z] #13 0x00007ff6c5c57978 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd87978)

[2025-07-09T20:23:08.285Z] #14 0x00007ff6c5c7f073 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdaf073)

[2025-07-09T20:23:08.285Z] #15 0x00007ff6c5c7cf33 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdacf33)

[2025-07-09T20:23:08.285Z] #16 0x00007ff6c5c5cf78 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd8cf78)

[2025-07-09T20:23:08.285Z] #17 0x00007ff6c5cf0074 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe20074)

[2025-07-09T20:23:08.285Z] #18 0x00007ff6c5cb523f (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xde523f)

[2025-07-09T20:23:08.285Z] #19 0x00007ff6c5cc110a (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xdf110a)

[2025-07-09T20:23:08.285Z] #20 0x00007ff6c5cb4e91 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xde4e91)

[2025-07-09T20:23:08.285Z] #21 0x00007ff6c5d407a1 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe707a1)

[2025-07-09T20:23:08.285Z] #22 0x00007ff6c5d43643 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe73643)

[2025-07-09T20:23:08.285Z] #23 0x00007ff6c5d4433e (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe7433e)

[2025-07-09T20:23:08.285Z] #24 0x00007ff6c5d4351d (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe7351d)

[2025-07-09T20:23:08.285Z] #25 0x00007ff6c5d40ac3 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe70ac3)

[2025-07-09T20:23:08.285Z] #26 0x00007ff6c5cf0731 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xe20731)

[2025-07-09T20:23:08.285Z] #27 0x00007ff6c5c400ac (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd700ac)

[2025-07-09T20:23:08.285Z] #28 0x00007ff6c5c43a28 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd73a28)

[2025-07-09T20:23:08.285Z] #29 0x00007ff6c5c4ae46 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd7ae46)

[2025-07-09T20:23:08.285Z] #30 0x00007ff6c5c39673 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd69673)

[2025-07-09T20:23:08.285Z] #31 0x00007ff6c5c492f4 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0xd792f4)

[2025-07-09T20:23:08.285Z] #32 0x00007ff6c553a559 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x66a559)

[2025-07-09T20:23:08.285Z] #33 0x00007ff6c5539324 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x669324)

[2025-07-09T20:23:08.285Z] #34 0x00007ff6c55397db (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x6697db)

[2025-07-09T20:23:08.285Z] #35 0x00007ff6c553b742 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x66b742)

[2025-07-09T20:23:08.285Z] #36 0x00007ff6c5380770 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x4b0770)

[2025-07-09T20:23:08.285Z] #37 0x00007ff6c5380307 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x4b0307)

[2025-07-09T20:23:08.285Z] #38 0x00007ff6cbe48c88 (C:\Users\ContainerAdministrator\AppData\Local\Programs\Swift\Toolchains\0.0.0+Asserts\usr\bin\swift-frontend.exe+0x6f78c88)

[2025-07-09T20:23:08.285Z] #39 0x00007fff5ed47ac4 (C:\Windows\System32\KERNEL32.DLL+0x17ac4)

[2025-07-09T20:23:08.285Z] #40 0x00007fff69f0a8c1 (C:\Windows\SYSTEM32\ntdll.dll+0x5a8c1)

To Reproduce
PR testing for #1400

Expected behavior
The compiler shouldn't crash.

Configuration (please complete the following information):

• Swift Version: swift-DEVELOPMENT-SNAPSHOT-2025-06-09-a
• OS: Windows
• OS Version: 2022

Regression information:
This didn't happen last week.

Additional context
Add any other context about the problem here.

consoleText-904.txt

[glessard]

@compnerd could #1340 have caused this?

[compnerd]

Hmm, I've not seen that. It might be triggered by it, but it seems to be passing on main (there was a cross-repo test as well and it passed CI on the PR itself). Perhaps something new?

[glessard]

The compiler for CI hasn't changed in a few weeks; quite odd.

[jmschonfeld]

@compnerd your cross-repo test would have used a swift compiler built from main (unless your swift repo branch is based on a snapshot tag) and the CI on the PR itself would have built against main of swift-foundation-icu and not your S-F-ICU PR so I don't think CI has yet to cover the swift-foundation change + swift-foundation-icu change + swift snapshot toolchain case and the Swift snapshot is a month old (from June 9th). Did this require any compiler changes at all when the two repo changes are combined together that might have landed after June 9th?

[compnerd]

Ah; hmm - yeah, the new feature ImportMacroAlias feature flag was relatively recent.

[jmschonfeld]

Ah; hmm - yeah, the new feature ImportMacroAlias feature flag was relatively recent.

Ah gotcha - if that landed after June 9th we may need to revert until we have a new nightly snapshot that includes the change

[glessard]

ImportMacroAliases comes from this commit: swiftlang/swift@c08372a

This hasn't made it into any nightly, let alone the Windows one.

It seems like we should revert #1340 until the nightlies do include the above commit.

[glessard]

Reverts:
swiftlang/swift-foundation-icu#65
#1416