[DebugInfo] Emit debug info for witness tables

[augusto2112]

This change emits debug info for witness tables passed into generic functions when a generic type is constrained to a protocol. This information is required for LLDB's generic expression evaluator to work in such functions.

rdar://104446865

[augusto2112]

@swift-ci smoke test

[slavapestov]

Keying this off of depth/index is insufficient. Eg in the following, we pass a witness table for the T.Element: Equatable conformance:

func f<T: Sequence>(_: T) where T.Element: Sequence {}

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[augusto2112]

@swift-ci test

[adrian-prantl]

@swift-ci test source compatibility

[augusto2112]

I think source compatibility passed, I see this at the end of the logs:

[2025-05-06T06:22:39.777Z] Action Summary:
[2025-05-06T06:22:39.777Z]      Passed: 354
[2025-05-06T06:22:39.777Z]      Failed: 0
[2025-05-06T06:22:39.777Z]     XFailed: 39
[2025-05-06T06:22:39.777Z]     UPassed: 0
[2025-05-06T06:22:39.777Z]       Total: 393
[2025-05-06T06:22:39.777Z] ========================================
[2025-05-06T06:22:39.777Z] Repository Summary:
[2025-05-06T06:22:39.777Z]       Total: 144
[2025-05-06T06:22:39.777Z] ========================================
[2025-05-06T06:22:39.777Z] Result: XFAIL

And later:

[2025-05-06T06:22:55.206Z] + ./swift-source-compat-suite/cleanup main
[2025-05-06T06:22:55.461Z] ** CLEANUP **
[2025-05-06T06:22:55.461Z] Deleting build and source directories...
[2025-05-06T06:28:25.205Z] Cancelling nested steps due to timeout
[2025-05-06T06:28:25.207Z] Sending interrupt signal to process
[2025-05-06T06:28:32.415Z] Traceback (most recent call last):
[2025-05-06T06:28:32.415Z]   File "/Users/ec2-user/jenkins/workspace/swift-PR-source-compat-suite-debug-macos/./swift-source-compat-suite/cleanup", line 95, in <module>
[2025-05-06T06:28:32.415Z]     sys.exit(main())
[2025-05-06T06:28:32.415Z]   File "/Users/ec2-user/jenkins/workspace/swift-PR-source-compat-suite-debug-macos/./swift-source-compat-suite/cleanup", line 80, in main
[2025-05-06T06:28:32.415Z]     common.check_execute([
[2025-05-06T06:28:32.415Z]   File "/Users/ec2-user/jenkins/workspace/swift-PR-source-compat-suite-debug-macos/swift-source-compat-suite/common.py", line 220, in check_execute
[2025-05-06T06:28:32.415Z] /Users/ec2-user/jenkins/workspace/swift-PR-source-compat-suite-debug-macos@tmp/durable-1321e01a/script.sh.copy: line 1: 34317 Terminated: 15          ./swift-source-compat-suite/cleanup main
[2025-05-06T06:28:32.418Z] script returned exit code 143

I'll rerun it just in case though

[augusto2112]

@swift-ci test source compatibility

[augusto2112]

@swift-ci test source compatibility

[augusto2112]

Looks like source compatibility aborts because of sccache:

20:09:24  + /usr/local/bin/sccache --stop-server
20:09:24  Stopping sccache server...
17:30:55  Sending interrupt signal to process
17:30:55  Aborted by [unknown](https://ci.swift.org/user/unknown)
17:31:02  /Users/ec2-user/jenkins/workspace/swift-PR-source-compat-suite-debug-macos@tmp/durable-fa95a614/script.sh.copy: line 1: 63847 Terminated: 15          /usr/local/bin/sccache --stop-server 2> /dev/null

[adrian-prantl]

Let's merge this and watch the bots closely. Did it pass source-compatibility locally?

[augusto2112]

@swift-ci test source compatibility