iOS: Breakpoint not hit in classes containing static fields that are initialized inline

[rolfbjarne]

From @prollin on Fri, 15 Mar 2024 17:21:43 GMT

Steps to Reproduce

1. create a new ios project: dotnet new iOS
2. in AppDelegate.cs add a new field: private static int foo = 42;
3. add a breakpoint in FinishedLaunching()
4. launch app

Expected Behavior

Breakpoint is hit

Actual Behavior

Breakpoint not hit

Environment

Visual Studio Code 1.87.2 + .NET MAUI 0.9.7 + C# Dev Kit 1.4.29

Version information

Version: 1.87.2 (Universal)
Commit: 863d2581ecda6849923a2118d93a088b0745d9d6
Date: 2024-03-08T15:21:31.043Z
Electron: 27.3.2
ElectronBuildId: 26836302
Chromium: 118.0.5993.159
Node.js: 18.17.1
V8: 11.8.172.18-electron.0
OS: Darwin arm64 23.1.0

dotnet --info

```

.NET SDK:
Version: 8.0.202
Commit: 25674bb2f4
Workload version: 8.0.200-manifests.a7f084b6

Runtime Environment:
OS Name: Mac OS X
OS Version: 14.1
OS Platform: Darwin
RID: osx-arm64
Base Path: /usr/local/share/dotnet/sdk/8.0.202/

.NET workloads installed:
[ios]
Installation Source: SDK 8.0.200
Manifest Version: 17.2.8043/8.0.100
Manifest Path: /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.ios/17.2.8043/WorkloadManifest.json
Install Type: FileBased

[maui]
Installation Source: SDK 8.0.200
Manifest Version: 8.0.7/8.0.100
Manifest Path: /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.maui/8.0.7/WorkloadManifest.json
Install Type: FileBased

[android]
Installation Source: SDK 8.0.200
Manifest Version: 34.0.85/8.0.100
Manifest Path: /usr/local/share/dotnet/sdk-manifests/8.0.100/microsoft.net.sdk.android/34.0.85/WorkloadManifest.json
Install Type: FileBased

Host:
Version: 8.0.3
Architecture: arm64
Commit: 9f4b1f5

.NET SDKs installed:
8.0.202 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
Microsoft.AspNetCore.App 8.0.3 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 8.0.3 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
x64 [/usr/local/share/dotnet/x64]
registered at [/etc/dotnet/install_location_x64]

Environment variables:
Not set

global.json file:
Not found

</details>

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_Copied from original issue xamarin/xamarin-macios#20315_

[rolfbjarne]

From @prollin on Sun, 24 Mar 2024 00:10:34 GMT

@rolfbjarne just had a chance to confirm that this also happens in Visual Studio Professional (tested on 17.9.4 as well as 17.10.0 Preview 2.0) with a mac build host so it is not exclusive to VSCode.

This problem seem to be at the core of our inability to properly debug our app on iOS (both simulator and device) since we use static classes/variables extensively. With such a simple repro case, could this be escalated? AFAIK this has been an issue since at least net8 release for us (we only were able to narrow it down to this clear repro case recently)

[rolfbjarne]

From @rolfbjarne on Mon, 25 Mar 2024 17:39:33 GMT

I can reproduce, and since it's happening in VS as well, I believe dotnet/runtime is probably a more correct place for this issue.

[rolfbjarne]

From @rolfbjarne on Mon, 25 Mar 2024 17:39:45 GMT

FWIW I can reproduce the problem.

[mdh1418]

It looks like this is a regression. .NET 7.0.408 iOS app can still hit the breakpoint with a static field initialized inline.

[prollin]

Is there any known workaround to this issue? (aside from avoiding inline statics which would require a lot of refactoring on our end)
This is a pretty strong showstopper for us.

[thaystg]

Not yet. My goal is to work on it tomorrow. I will let you know when I have any news.

[thaystg]

@rolfbjarne a possible workaround should be enable running with interpreter, but I don't know how to do it and if this is possible in the ios template.
Can you help us with that?

[rolfbjarne]

@rolfbjarne a possible workaround should be enable running with interpreter, but I don't know how to do it and if this is possible in the ios template. Can you help us with that?

Add this to the project to run with the interpreter:

<PropertyGroup>
    <UseInterpreter>true</UseInterpreter>
</PropertyGroup>

[prollin]

I can confirm that explicitely enabling the interpreter allows the breakpoint to be hit in the sample project.
I thought <UseInterpreter> was enabled by default in net8-ios project since afaik it is for maui projects (for debug configuration)

Regardless, we prefer to force disable <UseInterpreter> since we measured significant performance issues in our use cases, and we prefer our debug build to be as close to the release builds as possible.

Is a fix possible without having to enable <UseInterpreter>?

[thaystg]

The PR is already opened to fix it. this is only a workaround while the fix is not shipped.

[prollin]

Will this be included in the next 8.0.X release? 8.0.5?

[thaystg]

Will this be included in the next 8.0.X release? 8.0.5?

Yes