Declaration conflict and unknown extension reference errors after upgrading from 3.6.0 to 3.7.1

[juicyfru1t]

After upgrading Periphery from version 3.6.0 to 3.7.1, the analysis fails with indexing errors that did not occur in
the previous version.

Environment:

• Periphery version: 3.7.1 (previously 3.6.0 - worked fine)
• Xcode version: 26.3.0
• macOS version: Darwin 25.3.0
• Project type: Large multi-module iOS project with mixed Swift/Objective-C codebase

Errors:

Error: Unknown extended reference kind for extension 'extension'

Declaration conflict detected: a declaration with the USR 'c:@e@HHErrorTypeCode@HHErrorCommonBadRequest' has already
been indexed.

Command PhaseScriptExecution failed with a nonzero exit code

The HHErrorTypeCode and number of other files are Objective-C enums that may be bridged to Swift

I can provide more context if needed. Any hints how to fix it?

[ileitch]

Can you please provide a project that reproduces the issue?

[juicyfru1t]

Sadly, I don't think so. The project is private and huge, so I don't think I can reproduce the same exact setup in an
MVP. The project has had Periphery set up for a few years, and we haven't faced any issues until now. I will try to
remove these Objective-C files to see if it helps. But maybe you have any idea what might have broken in the 3.7.0
update? I assume something affected Objective-C handling.

[ileitch]

Error: Unknown extended reference kind for extension 'extension'

This is the actual failure. 3.7.0 uses a dfferent lbrary for parsing the index store, so that's the most likely cause. Some extension is not being identifed correctly, i.e. Periphery doesn't know if its a class/struct/protocol/enum extension. You can build Periphery locally and update this line to print the full declaraton.

Declaration conflict detected: a declaration with the USR 'c:@e@HHErrorTypeCode@HHErrorCommonBadRequest' has already
been indexed.

This is just a warning for now, but will become an error soon. You likely have build targets with non-unique names.

[danieleformichelli]

I can replicate this as well 🙏 Unfortunately I also can't share the private project.
Maybe it could make sense to improve the error message to make investigation easier for this issue and anything similar that might happen in the future?

[juicyfru1t]

Minor update: I might have found the issue - we had a Swift extension for Objective-C code. I'm currently migrating away from Objective-C and will report back with results in a few days. If the issue disappears after the migration, it would
confirm that Swift extension of Objective-C code was the cause.

[juicyfru1t]

so yes, can confirm that the problem was with swift extension of Objective-C code. after removing all of it from codebase periphery works fine at 3.7.2 version. I assume the issue can be closed

[danieleformichelli]

so yes, can confirm that the problem was with swift extension of Objective-C code. after removing all of it from codebase periphery works fine at 3.7.2 version. I assume the issue can be closed

I think the issue is still relevant until the relative PR is merged and released

[patryk-sredzinski]

Adding another data point from our iOS project.

Environment

• Periphery 3.7.2 (Homebrew formula)
• Xcode 26.4.0
• macOS Darwin 25.3.0

Failure

Periphery fails during scan with:

Error: Unknown extended reference kind for extension 'extension'
Command PhaseScriptExecution failed with a nonzero exit code

What we tested

• 3.7.2: fails
• 3.7.1: fails
• 3.6.0: works (scan completes)