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Fix Android support #22

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Fix Android support #22

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340058b
Use default C++ language standard
colemancda Jun 8, 2025
5ea4600
Fix Android support
colemancda Jun 8, 2025
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15 changes: 7 additions & 8 deletions Package.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -27,17 +27,17 @@ let openCombineShimTarget: Target = .target(
dependencies: [
"OpenCombine",
.target(name: "OpenCombineDispatch",
condition: .when(platforms: supportedPlatforms.except([.wasi]))),
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))),
.target(name: "OpenCombineFoundation",
condition: .when(platforms: supportedPlatforms.except([.wasi]))),
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))),
]
)
let openCombineTarget: Target = .target(
name: "OpenCombine",
dependencies: [
.target(
name: "COpenCombineHelpers",
condition: .when(platforms: supportedPlatforms.except([.wasi]))
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))
),
],
exclude: [
Expand All @@ -53,7 +53,7 @@ let openCombineFoundationTarget: Target = .target(
"OpenCombine",
.target(
name: "COpenCombineHelpers",
condition: .when(platforms: supportedPlatforms.except([.wasi]))
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))
),
]
)
Expand All @@ -66,9 +66,9 @@ let openCombineTestsTarget: Target = .testTarget(
dependencies: [
"OpenCombine",
.target(name: "OpenCombineDispatch",
condition: .when(platforms: supportedPlatforms.except([.wasi]))),
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))),
.target(name: "OpenCombineFoundation",
condition: .when(platforms: supportedPlatforms.except([.wasi]))),
condition: .when(platforms: supportedPlatforms.except([.wasi, .android]))),
],
swiftSettings: [
.unsafeFlags(["-enable-testing"]),
Expand All @@ -90,8 +90,7 @@ let package = Package(
openCombineFoundationTarget,
openCombineDispatchTarget,
openCombineTestsTarget,
],
cxxLanguageStandard: .cxx17
]
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LGTM except for this change. Could you elaborate on why this change is necessary?

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@colemancda colemancda Jun 18, 2025 •
edited
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There seems to be some CPP interop issue with Android when not using the default setting.

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@colemancda Thank you for the explanation. However, I don't think relying on default settings is a good approach as it may introduce maintenance burden for future upgrades and it also breaks other platform's build currently (See the failure CI - https://github.com/OpenSwiftUIProject/OpenCombine/actions/runs/15523371994/job/44321270577?pr=22).

Here are my suggestions:

  • Test different cxxLanguageStandard explicitly: Could you test the Android build environment with different explicit cxxLanguageStandard values to determine which specific setting works? We can then use different explicit standards for different OS platforms if needed. If a higher standard is required, we can also upgrade directly and adapt the code accordingly.
  • Share the specific build errors: Could you please share the actual error messages you're encountering with .cxx17? This would help us determine if we can stick with a unified cxxLanguageStandard (e.g., .cxx17) and handle the compatibility at the code level instead.
  • Consider adding Android CI workflow: I'm not familiar with the current Android build environment setup. If possible, would you mind also adding an Android CI build workflow? This would help us catch such cross-platform issues earlier and ensure better compatibility going forward.

Relying on implicit defaults makes the build configuration less predictable and harder to maintain across Swift toolchain versions. Let's work together to find a solution that uses explicit settings while maintaining Android compatibility.

)

// MARK: Helpers
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2 changes: 1 addition & 1 deletion Sources/OpenCombine/CombineIdentifier.swift
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Expand Up @@ -9,7 +9,7 @@
@_implementationOnly import COpenCombineHelpers
#endif

#if os(WASI)
#if os(WASI) || os(Android)
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The fallback for generating combine identifiers on Android is non-atomic and not thread-safe, which may produce duplicate IDs under concurrent use. Consider using an atomic counter or lock to ensure uniqueness.

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private var __identifier: UInt64 = 0

internal func __nextCombineIdentifier() -> UInt64 {
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2 changes: 1 addition & 1 deletion Sources/OpenCombine/Helpers/Locking.swift
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Expand Up @@ -9,7 +9,7 @@
@_implementationOnly import COpenCombineHelpers
#endif

#if os(WASI)
#if os(WASI) || os(Android)
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Stubbing out the lock on Android removes all mutual exclusion, which can lead to data races in multithreaded contexts. Consider providing a real lock implementation or documenting that this platform build is not thread-safe.

Suggested change
#if os(WASI) || os(Android)
#if os(WASI)
// Note: The WASI platform is assumed to run in a single-threaded environment.
// This implementation is not thread-safe.

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This will only be used on main thread in any case.

internal struct __UnfairLock { // swiftlint:disable:this type_name
internal static func allocate() -> UnfairLock { return .init() }
internal func lock() {}
Expand Down
2 changes: 1 addition & 1 deletion Sources/OpenCombine/Publishers/Publishers.Breakpoint.swift
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Expand Up @@ -5,7 +5,7 @@
// Created by Sergej Jaskiewicz on 03.12.2019.
//

#if !os(WASI)
#if !(os(WASI) || os(Android))

#if canImport(COpenCombineHelpers)
@_implementationOnly import COpenCombineHelpers
Expand Down
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