Linker emits "duplicate symbol" errors with Xcode 15 - Microsoft.iOS 16.4.7099

[actus-reus]

Steps to Reproduce

1. Use Xcode 15 and Microsoft.iOS 16.4.7099
2. Create a net7.0-ios library project binding to an native library (*.a)
3. Create a net7.0-ios application project and reference binding library project
4. Build

Expected Behavior

The application project should build without error or warning as it does with Xcode 14

Actual Behavior

The new Xcode 15 linker reports "duplicate symbols" errors in the native library of the binding project. The error points the duplicated symbols twice to the exact same library and location. No problem with Xcode 14. The only way to make the project compile with Xcode 15 is to fallback to the Xcode 14 classic linker by inserting:

<_MainLinkerFlags Include="-ld64" />

in the application project. But the fallback might be dropped by Apple at any point.

See #18719 and https://developer.apple.com/forums/thread/736590

Environment

Version information

Visual Studio Community 2022 for Mac
Version 17.6.4 (build 472)
Installation UUID: 9be326a3-8594-4e74-8c82-4905d251aaf1

Runtime
.NET 7.0.3 (64-bit)
Architecture: Arm64
Microsoft.macOS.Sdk 13.1.1007; git-rev-head:8afca776a0a96613dfb7200e0917bb57f9ed5583; git-branch:release/7.0.1xx-xcode14.2

Roslyn (Language Service)
4.6.0-3.23180.6+99e956e42697a6dd886d1e12478ea2b27cceacfa

NuGet
Version: 6.4.0.117

.NET SDK (Arm64)
SDK: /usr/local/share/dotnet/sdk/7.0.308/Sdks
SDK Versions:
	7.0.308
	7.0.307
	7.0.304
	7.0.203
	6.0.414
	6.0.413
	6.0.410
	6.0.408
MSBuild SDKs: /Applications/Visual Studio.app/Contents/MonoBundle/MSBuild/Current/bin/Sdks

.NET SDK (x64)
SDK Versions:
	7.0.400
	6.0.414
	6.0.413
	6.0.410
	6.0.106
	6.0.102
	5.0.408
	5.0.405
	3.1.426
	3.1.420
	3.1.416

.NET Runtime (Arm64)
Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
	7.0.11
	7.0.10
	7.0.7
	7.0.5
	6.0.22
	6.0.21
	6.0.18
	6.0.16

.NET Runtime (x64)
Runtime: /usr/local/share/dotnet/x64/dotnet
Runtime Versions:
	7.0.10
	6.0.22
	6.0.21
	6.0.18
	6.0.6
	6.0.2
	5.0.17
	5.0.14
	3.1.32
	3.1.26
	3.1.22

Xamarin.Profiler
Version: 1.8.0.49
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

Updater
Version: 11

Xamarin.Android
Version: 13.2.1.2 (Visual Studio Community)
Commit: xamarin-android/d17-5/a8a26c7
Android SDK: /Users/emmanuel/Library/Developer/Xamarin/android-sdk-macosx
	Supported Android versions:
		8.0  (API level 26)
		12.0 (API level 31)
		8.1  (API level 27)
		11.0 (API level 30)
		10.0 (API level 29)
		9.0  (API level 28)
		13.0 (API level 33)

SDK Command-line Tools Version: 7.0
SDK Platform Tools Version: 34.0.4
SDK Build Tools Version: 32.0.0

Build Information: 
Mono: d9a6e87
Java.Interop: xamarin/java.interop/d17-5@149d70fe
SQLite: xamarin/sqlite/3.40.1@68c69d8
Xamarin.Android Tools: xamarin/xamarin-android-tools/d17-5@ca1552d

Microsoft Build of OpenJDK
Java SDK: /Library/Java/JavaVirtualMachines/microsoft-11.jdk
11.0.16.1
Android Designer EPL code available here:
https://github.com/xamarin/AndroidDesigner.EPL

Eclipse Temurin JDK
Java SDK: /Library/Java/JavaVirtualMachines/temurin-8.jdk
1.8.0.302
Android Designer EPL code available here:
https://github.com/xamarin/AndroidDesigner.EPL

Android SDK Manager
Version: 17.6.0.50
Hash: a715dca
Branch: HEAD
Build date: 2023-09-07 02:05:26 UTC

Android Device Manager
Version: 0.0.0.1309
Hash: 06e3e77
Branch: HEAD
Build date: 2023-09-07 02:05:26 UTC

Apple Developer Tools
Xcode: 15.0 22265
Build: 15A240d

Xamarin.Mac
Version: 9.3.0.6 Visual Studio Community
Hash: 97731c92c
Branch: xcode14.3
Build date: 2023-04-11 22:38:35-0400

Xamarin.iOS
Version: 16.4.0.6 Visual Studio Community
Hash: 97731c92c
Branch: xcode14.3
Build date: 2023-04-11 22:38:36-0400

Xamarin Designer
Version: 17.6.3.9
Hash: 2648399ae8
Branch: remotes/origin/d17-6
Build date: 2023-09-07 02:05:20 UTC

Build Information
Release ID: 1706040472
Git revision: 0b8c2cb9f01ef14a2b07ff4ea047268c8756fee6
Build date: 2023-09-07 02:03:50+00
Build branch: release-17.6
Build lane: release-17.6

Operating System
Mac OS X 13.6.0
Darwin 22.6.0 Darwin Kernel Version 22.6.0
    Fri Sep 15 13:41:30 PDT 2023
    root:xnu-8796.141.3.700.8~1/RELEASE_ARM64_T8103 arm64

Enabled user installed extensions
.NET Core Extensions 0.7

Build Logs

MoveSenseTestApp_Debug_Build_2023-09-29T07_04_08.7561760Z.msbuild.log

Example Project (If Possible)

ld64.zip

Note that the native library had to be removed from the sample project for its size if over 125MB.

[dalexsoto]

This is a known issue, when using Xcode 15, we still recommend using ld_classic this will be fixed once we figure out all the issues on our end with ld_prime so the workaround for now is

<MtouchExtraArgs>-gcc_flags "-Xlinker -ld_classic"</MtouchExtraArgs>

[deepshah11295]

This is a known issue, when using Xcode 15, we still recommend using ld_classic this will be fixed once we figure out all the issues on our end with ld_prime so the workaround for now is

<MtouchExtraArgs>-gcc_flags "-Xlinker -ld_classic"</MtouchExtraArgs>

where we need to add this @dalexsoto @actus-reus @anaisbetts @radical

[actus-reus]

I used

<ItemGroup>
    <_MainLinkerFlags Include="-ld64" />
 </ItemGroup>

within the <Project Sdk="Microsoft.NET.Sdk> scope.

[deepshah11295]

scope

send me the path so I can add it

[rolfbjarne]

This will be fixed in our .NET 8 release, which comes with support for Xcode 15.