Mono debugger crashes attempting to breakpoint in a DIM in a generic interface

[jpobst]

Description

If you try to stop at a breakpoint (or step into) a default interface method inside a generic interface, Mono crashes with a native stacktrace.

Reproduction Steps

• Android application template (This happens for both Xamarin "Classic" and .NET 6)
• Paste in the following types:

class TestClass<T> : ITestGeneric<T>
{
}

interface ITestGeneric<T> : ITestBase
{
	void ITestBase.DoThing () => Console.WriteLine ();
}

interface ITestBase
{
	void DoThing ();
}

• Call DIM in OnCreate:

var c = new TestClass<string> ();
((ITestBase)c).DoThing ();

Run and code will succeed.

• Set a breakpoint on the Console.WriteLine (); and the process will crash when the breakpoint is hit.

Expected behavior

Debugger stops at breakpoint.

Actual behavior

Message printed in adb logcat:

01-27 16:03:21.871 23092 23113 E Lib_Sample_Net: * Assertion at /__w/1/s/src/mono/mono/mini/mini-exceptions.c:879, condition `klass' not met
--------- beginning of crash
01-27 16:03:21.872 23092 23113 F libc    : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 23113 (Debugger agent), pid 23092 (Lib_Sample_Net6)
01-27 16:03:21.889 14296 14305 W e.android.euic: Reducing the number of considered missed Gc histogram windows from 104 to 100
01-27 16:03:21.930 23121 23121 I crash_dump64: obtaining output fd from tombstoned, type: kDebuggerdTombstoneProto
01-27 16:03:21.931   828   828 I tombstoned: received crash request for pid 23113
01-27 16:03:21.932 23121 23121 I crash_dump64: performing dump of process 23092 (target tid = 23113)
01-27 16:03:21.945 23121 23121 E DEBUG   : failed to read /proc/uptime: Permission denied
01-27 16:03:22.068  1794  2221 D ConnectivityService: NetReassign [no changes]
01-27 16:03:22.159 23121 23121 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-27 16:03:22.159 23121 23121 F DEBUG   : Build fingerprint: 'google/bonito/bonito:12/SQ1A.211205.008/7888514:user/release-keys'
01-27 16:03:22.159 23121 23121 F DEBUG   : Revision: 'MP1.0'
01-27 16:03:22.159 23121 23121 F DEBUG   : ABI: 'arm64'
01-27 16:03:22.159 23121 23121 F DEBUG   : Timestamp: 2022-01-27 16:03:21.944731316-0600
01-27 16:03:22.159 23121 23121 F DEBUG   : Process uptime: 0s
01-27 16:03:22.159 23121 23121 F DEBUG   : Cmdline: com.companyname.Generic_Binding_Lib_Sample_Net6
01-27 16:03:22.159 23121 23121 F DEBUG   : pid: 23092, tid: 23113, name: Debugger agent  >>> com.companyname.Generic_Binding_Lib_Sample_Net6 <<<
01-27 16:03:22.159 23121 23121 F DEBUG   : uid: 10468
01-27 16:03:22.159 23121 23121 F DEBUG   : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
01-27 16:03:22.159 23121 23121 F DEBUG   :     x0  0000000000000000  x1  0000000000005a49  x2  0000000000000006  x3  0000007956a86320
01-27 16:03:22.159 23121 23121 F DEBUG   :     x4  6e6d6e6c2e627172  x5  6e6d6e6c2e627172  x6  6e6d6e6c2e627172  x7  7f7f7f7f7f7f7f7f
01-27 16:03:22.159 23121 23121 F DEBUG   :     x8  00000000000000f0  x9  da80a0e513e6a44f  x10 0000000000000000  x11 ffffff80fffffbdf
01-27 16:03:22.159 23121 23121 F DEBUG   :     x12 0000000000000001  x13 000000000000005d  x14 0000007956a851c0  x15 0033cca14d03d5e0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x16 0000007c7040e050  x17 0000007c703eaeb0  x18 000000795668c000  x19 0000000000005a34
01-27 16:03:22.159 23121 23121 F DEBUG   :     x20 0000000000005a49  x21 00000000ffffffff  x22 0000000000000000  x23 000000795a516c38
01-27 16:03:22.159 23121 23121 F DEBUG   :     x24 0000007956a86ac0  x25 0000007b5709ebc8  x26 0000007956a86ac0  x27 0000007956a86bc0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x28 0000007956a879f0  x29 0000007956a863a0
01-27 16:03:22.159 23121 23121 F DEBUG   :     lr  0000007c7039dba0  sp  0000007956a86300  pc  0000007c7039dbcc  pst 0000000000000000
01-27 16:03:22.159 23121 23121 F DEBUG   : backtrace:
01-27 16:03:22.159 23121 23121 F DEBUG   :       #00 pc 000000000004fbcc  /apex/com.android.runtime/lib64/bionic/libc.so (abort+164) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #01 pc 0000000000031598  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonodroid.so (xamarin::android::internal::MonodroidRuntime::mono_log_handler(char const*, char const*, char const*, int, void*)+144) (BuildId: ab750de5bc2960d28ad97dee10de0c633f16f369)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #02 pc 0000000000266afc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #03 pc 0000000000266c28  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #04 pc 0000000000266c6c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #05 pc 00000000001e7cfc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_get_generic_context_from_stack_frame+312) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #06 pc 00000000001e8198  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #07 pc 00000000001e8498  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #08 pc 00000000001e6db0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_walk_stack_with_state+80) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #09 pc 000000000000aec4  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #10 pc 0000000000010da0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #11 pc 00000000000171c8  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #12 pc 00000000000b11b0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #13 pc 00000000000b105c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #14 pc 00000000000b1910  /apex/com.android.runtime/lib64/bionic/libc.so (__pthread_start(void*)+264) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #15 pc 00000000000513f0  /apex/com.android.runtime/lib64/bionic/libc.so (__start_thread+64) (BuildId: ba489d4985c0cf173209da67405662f9)

Visual Studio reports this as:

EXCEPTION: Mono.Debugging.Soft.DisconnectedException: The connection with the debugger has been lost. The target application may have exited. ---> Mono.Debugger.Soft.VMDisconnectedException: Exception of type 'Mono.Debugger.Soft.VMDisconnectedException' was thrown.
   at Mono.Debugger.Soft.ThreadMirror.GetFrames() in C:\a\1\s\External\debugger-libs\Mono.Debugger.Soft\Mono.Debugger.Soft\ThreadMirror.cs:line 28
   at Mono.Debugging.Soft.SoftDebuggerBacktrace..ctor(SoftDebuggerSession session, ThreadMirror thread) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerBacktrace.cs:line 64
   at Mono.Debugging.Soft.SoftDebuggerSession.HandleBreakEventSet(Event[] es, Boolean dequeuing) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 2167
   at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler() in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 1786

Regression?

No response

Known Workarounds

No response

Configuration

Google Pixel 3a XL
Microsoft Visual Studio Enterprise 2022 (64-bit)
Version 17.0.5
Xamarin.Android SDK 12.1.0.5 (d17-0/6b0e6b2)
Xamarin.Android Reference Assemblies and MSBuild support.
Mono: c633fe9
Java.Interop: xamarin/java.interop/d17-0@febb1367
ProGuard: Guardsquare/proguard@912d149
SQLite: xamarin/sqlite@a575761
Xamarin.Android Tools: xamarin/xamarin-android-tools/d17-0@a5194e9

Other information

No response

Tagging subscribers to this area: @tommcdon
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

If you try to stop at a breakpoint (or step into) a default interface method inside a generic interface, Mono crashes with a native stacktrace.

Reproduction Steps

• Android application template (This happens for both Xamarin "Classic" and .NET 6)
• Paste in the following types:

class TestClass<T> : ITestGeneric<T>
{
}

interface ITestGeneric<T> : ITestBase
{
	void ITestBase.DoThing () => Console.WriteLine ();
}

interface ITestBase
{
	void DoThing ();
}

• Call DIM in OnCreate:

var c = new TestClass<string> ();
((ITestBase)c).DoThing ();

Run and code will succeed.

• Set a breakpoint on the Console.WriteLine (); and the process will crash when the breakpoint is hit.

Expected behavior

Debugger stops at breakpoint.

Actual behavior

Message printed in adb logcat:

01-27 16:03:21.871 23092 23113 E Lib_Sample_Net: * Assertion at /__w/1/s/src/mono/mono/mini/mini-exceptions.c:879, condition `klass' not met
--------- beginning of crash
01-27 16:03:21.872 23092 23113 F libc    : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 23113 (Debugger agent), pid 23092 (Lib_Sample_Net6)
01-27 16:03:21.889 14296 14305 W e.android.euic: Reducing the number of considered missed Gc histogram windows from 104 to 100
01-27 16:03:21.930 23121 23121 I crash_dump64: obtaining output fd from tombstoned, type: kDebuggerdTombstoneProto
01-27 16:03:21.931   828   828 I tombstoned: received crash request for pid 23113
01-27 16:03:21.932 23121 23121 I crash_dump64: performing dump of process 23092 (target tid = 23113)
01-27 16:03:21.945 23121 23121 E DEBUG   : failed to read /proc/uptime: Permission denied
01-27 16:03:22.068  1794  2221 D ConnectivityService: NetReassign [no changes]
01-27 16:03:22.159 23121 23121 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-27 16:03:22.159 23121 23121 F DEBUG   : Build fingerprint: 'google/bonito/bonito:12/SQ1A.211205.008/7888514:user/release-keys'
01-27 16:03:22.159 23121 23121 F DEBUG   : Revision: 'MP1.0'
01-27 16:03:22.159 23121 23121 F DEBUG   : ABI: 'arm64'
01-27 16:03:22.159 23121 23121 F DEBUG   : Timestamp: 2022-01-27 16:03:21.944731316-0600
01-27 16:03:22.159 23121 23121 F DEBUG   : Process uptime: 0s
01-27 16:03:22.159 23121 23121 F DEBUG   : Cmdline: com.companyname.Generic_Binding_Lib_Sample_Net6
01-27 16:03:22.159 23121 23121 F DEBUG   : pid: 23092, tid: 23113, name: Debugger agent  >>> com.companyname.Generic_Binding_Lib_Sample_Net6 <<<
01-27 16:03:22.159 23121 23121 F DEBUG   : uid: 10468
01-27 16:03:22.159 23121 23121 F DEBUG   : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
01-27 16:03:22.159 23121 23121 F DEBUG   :     x0  0000000000000000  x1  0000000000005a49  x2  0000000000000006  x3  0000007956a86320
01-27 16:03:22.159 23121 23121 F DEBUG   :     x4  6e6d6e6c2e627172  x5  6e6d6e6c2e627172  x6  6e6d6e6c2e627172  x7  7f7f7f7f7f7f7f7f
01-27 16:03:22.159 23121 23121 F DEBUG   :     x8  00000000000000f0  x9  da80a0e513e6a44f  x10 0000000000000000  x11 ffffff80fffffbdf
01-27 16:03:22.159 23121 23121 F DEBUG   :     x12 0000000000000001  x13 000000000000005d  x14 0000007956a851c0  x15 0033cca14d03d5e0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x16 0000007c7040e050  x17 0000007c703eaeb0  x18 000000795668c000  x19 0000000000005a34
01-27 16:03:22.159 23121 23121 F DEBUG   :     x20 0000000000005a49  x21 00000000ffffffff  x22 0000000000000000  x23 000000795a516c38
01-27 16:03:22.159 23121 23121 F DEBUG   :     x24 0000007956a86ac0  x25 0000007b5709ebc8  x26 0000007956a86ac0  x27 0000007956a86bc0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x28 0000007956a879f0  x29 0000007956a863a0
01-27 16:03:22.159 23121 23121 F DEBUG   :     lr  0000007c7039dba0  sp  0000007956a86300  pc  0000007c7039dbcc  pst 0000000000000000
01-27 16:03:22.159 23121 23121 F DEBUG   : backtrace:
01-27 16:03:22.159 23121 23121 F DEBUG   :       #00 pc 000000000004fbcc  /apex/com.android.runtime/lib64/bionic/libc.so (abort+164) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #01 pc 0000000000031598  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonodroid.so (xamarin::android::internal::MonodroidRuntime::mono_log_handler(char const*, char const*, char const*, int, void*)+144) (BuildId: ab750de5bc2960d28ad97dee10de0c633f16f369)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #02 pc 0000000000266afc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #03 pc 0000000000266c28  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #04 pc 0000000000266c6c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #05 pc 00000000001e7cfc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_get_generic_context_from_stack_frame+312) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #06 pc 00000000001e8198  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #07 pc 00000000001e8498  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #08 pc 00000000001e6db0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_walk_stack_with_state+80) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #09 pc 000000000000aec4  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #10 pc 0000000000010da0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #11 pc 00000000000171c8  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #12 pc 00000000000b11b0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #13 pc 00000000000b105c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #14 pc 00000000000b1910  /apex/com.android.runtime/lib64/bionic/libc.so (__pthread_start(void*)+264) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #15 pc 00000000000513f0  /apex/com.android.runtime/lib64/bionic/libc.so (__start_thread+64) (BuildId: ba489d4985c0cf173209da67405662f9)

Visual Studio reports this as:

EXCEPTION: Mono.Debugging.Soft.DisconnectedException: The connection with the debugger has been lost. The target application may have exited. ---> Mono.Debugger.Soft.VMDisconnectedException: Exception of type 'Mono.Debugger.Soft.VMDisconnectedException' was thrown.
   at Mono.Debugger.Soft.ThreadMirror.GetFrames() in C:\a\1\s\External\debugger-libs\Mono.Debugger.Soft\Mono.Debugger.Soft\ThreadMirror.cs:line 28
   at Mono.Debugging.Soft.SoftDebuggerBacktrace..ctor(SoftDebuggerSession session, ThreadMirror thread) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerBacktrace.cs:line 64
   at Mono.Debugging.Soft.SoftDebuggerSession.HandleBreakEventSet(Event[] es, Boolean dequeuing) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 2167
   at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler() in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 1786

Regression?

No response

Known Workarounds

No response

Configuration

Google Pixel 3a XL
Microsoft Visual Studio Enterprise 2022 (64-bit)
Version 17.0.5
Xamarin.Android SDK 12.1.0.5 (d17-0/6b0e6b2)
Xamarin.Android Reference Assemblies and MSBuild support.
Mono: c633fe9
Java.Interop: xamarin/java.interop/d17-0@febb1367
ProGuard: Guardsquare/proguard@912d149
SQLite: xamarin/sqlite@a575761
Xamarin.Android Tools: xamarin/xamarin-android-tools/d17-0@a5194e9

Other information

No response

Author:	jpobst
Assignees:	-
Labels:	area-Diagnostics-coreclr, untriaged
Milestone:	-

Tagging subscribers to this area: @thaystg
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Issue Details

---

Description

If you try to stop at a breakpoint (or step into) a default interface method inside a generic interface, Mono crashes with a native stacktrace.

Reproduction Steps

• Android application template (This happens for both Xamarin "Classic" and .NET 6)
• Paste in the following types:

class TestClass<T> : ITestGeneric<T>
{
}

interface ITestGeneric<T> : ITestBase
{
	void ITestBase.DoThing () => Console.WriteLine ();
}

interface ITestBase
{
	void DoThing ();
}

• Call DIM in OnCreate:

var c = new TestClass<string> ();
((ITestBase)c).DoThing ();

Run and code will succeed.

• Set a breakpoint on the Console.WriteLine (); and the process will crash when the breakpoint is hit.

Expected behavior

Debugger stops at breakpoint.

Actual behavior

Message printed in adb logcat:

01-27 16:03:21.871 23092 23113 E Lib_Sample_Net: * Assertion at /__w/1/s/src/mono/mono/mini/mini-exceptions.c:879, condition `klass' not met
--------- beginning of crash
01-27 16:03:21.872 23092 23113 F libc    : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 23113 (Debugger agent), pid 23092 (Lib_Sample_Net6)
01-27 16:03:21.889 14296 14305 W e.android.euic: Reducing the number of considered missed Gc histogram windows from 104 to 100
01-27 16:03:21.930 23121 23121 I crash_dump64: obtaining output fd from tombstoned, type: kDebuggerdTombstoneProto
01-27 16:03:21.931   828   828 I tombstoned: received crash request for pid 23113
01-27 16:03:21.932 23121 23121 I crash_dump64: performing dump of process 23092 (target tid = 23113)
01-27 16:03:21.945 23121 23121 E DEBUG   : failed to read /proc/uptime: Permission denied
01-27 16:03:22.068  1794  2221 D ConnectivityService: NetReassign [no changes]
01-27 16:03:22.159 23121 23121 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-27 16:03:22.159 23121 23121 F DEBUG   : Build fingerprint: 'google/bonito/bonito:12/SQ1A.211205.008/7888514:user/release-keys'
01-27 16:03:22.159 23121 23121 F DEBUG   : Revision: 'MP1.0'
01-27 16:03:22.159 23121 23121 F DEBUG   : ABI: 'arm64'
01-27 16:03:22.159 23121 23121 F DEBUG   : Timestamp: 2022-01-27 16:03:21.944731316-0600
01-27 16:03:22.159 23121 23121 F DEBUG   : Process uptime: 0s
01-27 16:03:22.159 23121 23121 F DEBUG   : Cmdline: com.companyname.Generic_Binding_Lib_Sample_Net6
01-27 16:03:22.159 23121 23121 F DEBUG   : pid: 23092, tid: 23113, name: Debugger agent  >>> com.companyname.Generic_Binding_Lib_Sample_Net6 <<<
01-27 16:03:22.159 23121 23121 F DEBUG   : uid: 10468
01-27 16:03:22.159 23121 23121 F DEBUG   : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
01-27 16:03:22.159 23121 23121 F DEBUG   :     x0  0000000000000000  x1  0000000000005a49  x2  0000000000000006  x3  0000007956a86320
01-27 16:03:22.159 23121 23121 F DEBUG   :     x4  6e6d6e6c2e627172  x5  6e6d6e6c2e627172  x6  6e6d6e6c2e627172  x7  7f7f7f7f7f7f7f7f
01-27 16:03:22.159 23121 23121 F DEBUG   :     x8  00000000000000f0  x9  da80a0e513e6a44f  x10 0000000000000000  x11 ffffff80fffffbdf
01-27 16:03:22.159 23121 23121 F DEBUG   :     x12 0000000000000001  x13 000000000000005d  x14 0000007956a851c0  x15 0033cca14d03d5e0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x16 0000007c7040e050  x17 0000007c703eaeb0  x18 000000795668c000  x19 0000000000005a34
01-27 16:03:22.159 23121 23121 F DEBUG   :     x20 0000000000005a49  x21 00000000ffffffff  x22 0000000000000000  x23 000000795a516c38
01-27 16:03:22.159 23121 23121 F DEBUG   :     x24 0000007956a86ac0  x25 0000007b5709ebc8  x26 0000007956a86ac0  x27 0000007956a86bc0
01-27 16:03:22.159 23121 23121 F DEBUG   :     x28 0000007956a879f0  x29 0000007956a863a0
01-27 16:03:22.159 23121 23121 F DEBUG   :     lr  0000007c7039dba0  sp  0000007956a86300  pc  0000007c7039dbcc  pst 0000000000000000
01-27 16:03:22.159 23121 23121 F DEBUG   : backtrace:
01-27 16:03:22.159 23121 23121 F DEBUG   :       #00 pc 000000000004fbcc  /apex/com.android.runtime/lib64/bionic/libc.so (abort+164) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #01 pc 0000000000031598  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonodroid.so (xamarin::android::internal::MonodroidRuntime::mono_log_handler(char const*, char const*, char const*, int, void*)+144) (BuildId: ab750de5bc2960d28ad97dee10de0c633f16f369)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #02 pc 0000000000266afc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #03 pc 0000000000266c28  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #04 pc 0000000000266c6c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #05 pc 00000000001e7cfc  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_get_generic_context_from_stack_frame+312) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #06 pc 00000000001e8198  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #07 pc 00000000001e8498  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #08 pc 00000000001e6db0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (mono_walk_stack_with_state+80) (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #09 pc 000000000000aec4  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #10 pc 0000000000010da0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #11 pc 00000000000171c8  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmono-component-debugger.so (BuildId: 8f2c698b57b4e77652e4a2f24d841741b7be4cc4)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #12 pc 00000000000b11b0  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #13 pc 00000000000b105c  /data/app/~~eFrrzAI6TJ0O3PHLh-p2Qw==/com.companyname.Generic_Binding_Lib_Sample_Net6-BJMFf4uedhZHAVwqzceHXA==/lib/arm64/libmonosgen-2.0.so (BuildId: 4881f6ac8ca60bdb4b0c44c72440267b1b8f2a34)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #14 pc 00000000000b1910  /apex/com.android.runtime/lib64/bionic/libc.so (__pthread_start(void*)+264) (BuildId: ba489d4985c0cf173209da67405662f9)
01-27 16:03:22.159 23121 23121 F DEBUG   :       #15 pc 00000000000513f0  /apex/com.android.runtime/lib64/bionic/libc.so (__start_thread+64) (BuildId: ba489d4985c0cf173209da67405662f9)

Visual Studio reports this as:

EXCEPTION: Mono.Debugging.Soft.DisconnectedException: The connection with the debugger has been lost. The target application may have exited. ---> Mono.Debugger.Soft.VMDisconnectedException: Exception of type 'Mono.Debugger.Soft.VMDisconnectedException' was thrown.
   at Mono.Debugger.Soft.ThreadMirror.GetFrames() in C:\a\1\s\External\debugger-libs\Mono.Debugger.Soft\Mono.Debugger.Soft\ThreadMirror.cs:line 28
   at Mono.Debugging.Soft.SoftDebuggerBacktrace..ctor(SoftDebuggerSession session, ThreadMirror thread) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerBacktrace.cs:line 64
   at Mono.Debugging.Soft.SoftDebuggerSession.HandleBreakEventSet(Event[] es, Boolean dequeuing) in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 2167
   at Mono.Debugging.Soft.SoftDebuggerSession.EventHandler() in C:\a\1\s\External\debugger-libs\Mono.Debugging.Soft\SoftDebuggerSession.cs:line 1786

Regression?

No response

Known Workarounds

No response

Configuration

Google Pixel 3a XL
Microsoft Visual Studio Enterprise 2022 (64-bit)
Version 17.0.5
Xamarin.Android SDK 12.1.0.5 (d17-0/6b0e6b2)
Xamarin.Android Reference Assemblies and MSBuild support.
Mono: c633fe9
Java.Interop: xamarin/java.interop/d17-0@febb1367
ProGuard: Guardsquare/proguard@912d149
SQLite: xamarin/sqlite@a575761
Xamarin.Android Tools: xamarin/xamarin-android-tools/d17-0@a5194e9

Other information

No response

Author:	jpobst
Assignees:	-
Labels:	untriaged, area-Debugger-mono
Milestone:	-

[thaystg]

Fixed in this PR on mono that is not merged yet: mono/mono#21356
On dotnet runtime repo this fix is already merged: #60770
But I think we should wait for this PR: #64566 and then backport both to 6.0.
Also after this new PR is approved we should fix it on mono PR and then merge there and also backport.

@lambdageek what do you think?

[akoeplinger]

@thaystg the PRs were merged, is there anything left to do here?

[thaystg]

No, we can close.

[akoeplinger]

@thaystg ah I just noticed you mentioned backporting #64566 to 6.0, do we not need it anymore?

[thaystg]

We need to backport this: #60770
And also this: #64566