iOS swift app build fails with cyclic dependency error in Xcode 14+

Question

I have a swift iOS app with two static libraries - lib1 and lib2 (say). Lib2 has a dependency on Lib1 (ie it imports Lib1 to use its types). Lib1 and Lib2 are set as dependencies for the AppTarget (when built, results in the.app file).

I get the following cyclic dependency error when building Lib1. Similar error is observed when building the other targets.

SwiftDriverJobDiscovery normal x86_64 Compiling <FileName1>.swift (in target '<Lib1>' from project '<ProjectName>')
error: Cycle inside <Lib1>; building could produce unreliable results.
Cycle details:
→ Target '<Lib1>': Libtool /Users/<user-name>/<some-path>/<Lib1>.a normal
○ Target '<Lib1>' has Swift tasks not blocking downstream targets
○ Target '<Lib1>': SwiftGeneratePch normal x86_64 Compiling bridging header
○ Target '<Lib1>': SwiftCompile normal x86_64 Compiling <FileName2>.swift /Users/<user-name>/<some-path>/<Filename2>.swift
○ Target '<Lib1>': SwiftGeneratePch normal x86_64 Compiling bridging header
Raw dependency cycle trace:
target:  ->
node: <all> ->
command: <all> ->
node: /Users/<user-name/<some-path>/<Lib1>.a -> command: P1:target-<Lib1>-6d14b29d8d3402955e18e7b7c2cd5bd8502d5dd7097f7536813aba73cac1c1d5-:Debug:Libtool /Users/<user-name>/<some-path>/<Lib1>.a normal ->
node: /Users/<user-name>/<some-path>/x86_64/<FileName3>-8014457a59adc1f8a995a14873eb809b.o ->
command: P0:target-<Lib1>-6d14b29d8d3402955e18e7b7c2cd5bd8502d5dd7097f7536813aba73cac1c1d5-:Debug:SwiftDriver Compilation <Lib1> normal x86_64 com.apple.xcode.tools.swift.compiler ->
CYCLE POINT ->
customTask: <SwiftDriverJob identifier=-4908891831242875468 arch=x86_64 variant=normal job=<PlannedSwiftDriverJob [target(7)]:GeneratePch <Lib1> dependencies=["target(8)", "target(9)", "target(10)"]> isUsingWholeModuleOptimization=false compilerPath=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc> ->
customTask: <SwiftDriverJob identifier=-4908891831242875468 arch=x86_64 variant=normal job=<PlannedSwiftDriverJob [target(8)]:Compile <Lib1> <FileName2>.swift dependencies=["target(7)"]> isUsingWholeModuleOptimization=false compilerPath=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc> ->
customTask: <SwiftDriverJob identifier=-4908891831242875468 arch=x86_64 variant=normal job=<PlannedSwiftDriverJob [target(7)]:GeneratePch <Lib1> dependencies=["target(8)", "target(9)", "target(10)"]> isUsingWholeModuleOptimization=false compilerPath=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc>

In the above error message, FileName1 and FileName2 are swift files that invoke C++ methods using an intermediate ObjC++ bridge layer. I have two files named FileName3 but different extensions -.swift and.mm. Since, FileName2 is referred as.o here, I think it is referring to FileName3.mm (ie the ObjC++ file).

I have checked the code thoroughly for any form of cyclic dependency (like, two classes depending on each other - as mentioned in many stackoverflow posts), but it's all good. What's more, the same build worked on Xcode 13.x. After updating to Xcode 14.x, I'm getting this cyclic dependency error.

But in the last three lines of the error message, you can see a cyclic dependency.

• First step: [Target(7)] Generate pch and depends on [target(8), target(9), target(10)]
• Second step: [Target(8)] Compile FileName2.swift, depends on [target(7)]

Target(7) is dependent on target(8) and target(8) is dependent on target(7). What is target(7), target(8) etc? Where can I find out what kind of target it exactly is?

I use cmake to set the dependencies and generate the Xcode project.

What is this error? What am I missing here? I've been stuck for days and any help would be greatly appreciated.

Answer 1

After so much time spent on searching, this is the answer.

Checkout ctietze's answer to this post in Apple forum

defaults write com.apple.dt.XCBuild EnableSwiftBuildSystemIntegration 0

After disabling the new build system, I'm not getting the cyclic dependency error anymore.