feat: Capturing fatal CPPExceptions via cxa_throw

[philipphofmann]

📜 Description

Use fishhook to swap the __cxa_throw C++ exception handler for getting
stacktraces for unhandled C++ exceptions. This implementation is based
on the code in https://github.com/kstenerud/KSCrash.

The API stability check fails because I added a new experimental option enableUnhandledCPPExceptionsV2.

There are still a few open issues to address before making this GA; see #5309

💡 Motivation and Context

Fixes GH-4517

💚 How did you test it?

Testing Details macOS sample

Without the feature

https://sentry-sdks.sentry.io/issues/6590753526/events/d1bb9784083e40a8abfdb28ac2b9c34e/?project=5428557

With the feature

Invalid Argument

sentry-cocoa/Samples/macOS-Swift/Shared/CppSample.cpp

Lines 4 to 8 in e70c3aa

	void
	internalFunction(void)
	{
	throw std::invalid_argument("Internal function must not be called.");
	}

https://sentry-sdks.sentry.io/issues/6545237791/events/a393feb8d8b2401c8d6cedca5ce181a4/?project=5428557

rethrowNoActiveCPPException

sentry-cocoa/Samples/macOS-Swift/Shared/CppSample.cpp

Lines 22 to 28 in e70c3aa

	void
	Sentry::CppSample::rethrowNoActiveCPPException(void)
	{
	// Rethrowing an exception when there is no active exception will lead to std::terminate being
	// called.
	throw;
	}

https://sentry-sdks.sentry.io/issues/6617441025/events/30bc9db8d17b4dcd80d6473c57a3c36f/?project=5428557

C++ Exception from BG Thread

https://sentry-sdks.sentry.io/issues/6565152294/events/691f845d8dc04305b0cf376e2d21732b/?project=5428557

NoExcept C++ Exception

sentry-cocoa/Samples/macOS-Swift/Shared/CppSample.cpp

Lines 16 to 20 in e70c3aa

	void
	Sentry::CppSample::noExceptCppException() noexcept
	{
	throw std::invalid_argument("Invalid Argument.");
	}

https://sentry-sdks.sentry.io/issues/6565163235/events/d9dc157068994ed2879842dbaf5f477b/?project=5428557

Unhandled C++Exception from testflight iOS-Swift
https://sentry-sdks.sentry.io/issues/6623122757/events/85451edf3f324ad98a6293f1e2cc4b55/?project=5428557

📝 Checklist

You have to check all boxes before merging:

• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 8a967cd

[codecov]

Codecov Report

Attention: Patch coverage is 90.61662% with 35 lines in your changes missing coverage. Please review.

Project coverage is 86.049%. Comparing base (36d0487) to head (8a967cd).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...Crash/Recording/Tools/SentryCrashCxaThrowSwapper.c	88.446%	29 Missing ⚠️
...rding/Monitors/SentryCrashMonitor_CPPException.cpp	76.923%	6 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #5256       +/-   ##
=============================================
+ Coverage   85.933%   86.049%   +0.115%     
=============================================
  Files          394       397        +3     
  Lines        34217     34587      +370     
  Branches     14798     14988      +190     
=============================================
+ Hits         29404     29762      +358     
- Misses        4771      4785       +14     
+ Partials        42        40        -2     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryCrashIntegration.m	99.193% <100.000%> (+0.033%)	⬆️
Sources/Sentry/include/SentryCompiler.h	100.000% <100.000%> (ø)
...es/SentryCrash/Recording/Tools/SentryCrashMach-O.c	100.000% <100.000%> (ø)
...cording/Tools/SentryCrashPlatformSpecificDefines.h	100.000% <100.000%> (ø)
Sources/Swift/Core/SentryExperimentalOptions.swift	60.000% <100.000%> (+10.000%)	⬆️
...es/Swift/Helper/SentryEnabledFeaturesBuilder.swift	100.000% <100.000%> (ø)
...rding/Monitors/SentryCrashMonitor_CPPException.cpp	76.774% <76.923%> (+1.774%)	⬆️
...Crash/Recording/Tools/SentryCrashCxaThrowSwapper.c	88.446% <88.446%> (ø)

... and 8 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1226.69 ms	1239.35 ms	12.65 ms
Size	23.75 KiB	840.58 KiB	816.83 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
ed49f0c	1245.67 ms	1261.15 ms	15.48 ms
7bc3c0d	1212.35 ms	1228.94 ms	16.59 ms
881a955	1214.27 ms	1235.88 ms	21.61 ms
24e0744	1241.98 ms	1262.44 ms	20.46 ms
765dd70	1236.16 ms	1259.12 ms	22.96 ms
e8b11f8	1233.66 ms	1249.74 ms	16.08 ms
db533ee	1228.96 ms	1248.23 ms	19.28 ms
3f366ee	1242.28 ms	1260.80 ms	18.52 ms
6604dbb	1248.35 ms	1256.14 ms	7.79 ms
596ccc1	1223.80 ms	1249.44 ms	25.64 ms

App size

Revision	Plain	With Sentry	Diff
ed49f0c	21.58 KiB	632.13 KiB	610.55 KiB
7bc3c0d	20.76 KiB	427.35 KiB	406.59 KiB
881a955	22.85 KiB	407.63 KiB	384.78 KiB
24e0744	21.58 KiB	709.06 KiB	687.48 KiB
765dd70	23.76 KiB	819.58 KiB	795.81 KiB
e8b11f8	22.85 KiB	411.92 KiB	389.07 KiB
db533ee	21.58 KiB	547.02 KiB	525.44 KiB
3f366ee	20.76 KiB	427.84 KiB	407.08 KiB
6604dbb	22.84 KiB	402.56 KiB	379.72 KiB
596ccc1	22.84 KiB	401.44 KiB	378.59 KiB

Previous results on branch: fix/cpp-exceptions-v3

Startup times

Revision	Plain	With Sentry	Diff
fe1b364	1214.59 ms	1244.90 ms	30.31 ms
0143072	1219.62 ms	1252.60 ms	32.98 ms
1a55563	1219.78 ms	1245.86 ms	26.08 ms
05e5998	1235.76 ms	1255.39 ms	19.63 ms
12a2c05	1213.24 ms	1232.41 ms	19.16 ms
e102ea7	1239.84 ms	1254.65 ms	14.82 ms
d52d3e7	1233.12 ms	1255.00 ms	21.88 ms
6ac3949	1227.64 ms	1247.69 ms	20.06 ms
170787d	1225.39 ms	1246.92 ms	21.53 ms
181f6e4	1239.90 ms	1253.16 ms	13.27 ms

App size

Revision	Plain	With Sentry	Diff
fe1b364	23.76 KiB	838.03 KiB	814.27 KiB
0143072	23.76 KiB	825.26 KiB	801.49 KiB
1a55563	23.76 KiB	825.24 KiB	801.48 KiB
05e5998	23.76 KiB	839.39 KiB	815.63 KiB
12a2c05	23.76 KiB	825.23 KiB	801.47 KiB
e102ea7	23.76 KiB	825.28 KiB	801.51 KiB
d52d3e7	23.74 KiB	840.59 KiB	816.84 KiB
6ac3949	23.74 KiB	840.59 KiB	816.84 KiB
170787d	23.76 KiB	839.59 KiB	815.83 KiB
181f6e4	23.76 KiB	838.04 KiB	814.28 KiB

[supervacuus]

Inspected the changes since the last review. Except for one copypasta everything looks sensible.

I did not get into the details of why tests failed as a result of the unswap, beyond what we already discussed offline. So, for me, the current "fix" is accepted until #5309, since the only downside is keeping the indirect symbols in memory longer than necessary (which doesn't require a significant budget, and you already consider the potential failure mode of adding duplicates when swapping multiple times).

[philprime]

My knowledge on C/C++ is limited therefore I am not going to block this PR, but I did left a couple of comments for you to consider.

[philipphofmann]

The API Stability Check is supposed to fail due to adding a new experimental options enableUnhandledCPPExceptionsV2.

[zkacso-dev]

I don't see this flag mentioned in the documentation https://docs.sentry.io/platforms/apple/features/experimental-features/ .
Is it ready to use in a production app?

[kahest]

@zkacso-dev thanks for the ping - we'll add the option to the Experimental Features page. We recommend testing this feature in a pre-production environment and appreciate feedback you might have. We have a small list of items we want to follow up with before we make the feature non-experimental.

[philipphofmann]

Related docs PR to add this to the list of experimental features getsentry/sentry-docs#14731