Clang dependency scanning failure, fatal error: MTMathList.h not found.

[Janneman84]

I tried adding this SPM package to my projects. It keeps getting build errors:

Clang dependency scanning failure: While building module 'iosMath' imported from iosMath-0adfd710.input:1:
In file included from <module-includes>:1:
/Users/jandevries/Library/Developer/Xcode/DerivedData/MyExample-abseqhblaekbyudrurbpoucqjezl/SourcePackages/checkouts/iosMath/iosMath/render/MTMathUILabel.h:18:9: fatal error: 'MTMathList.h' file not found
iosMath-0adfd710.input:1:1: fatal error: could not build module 'iosMath'

I tried clearing all caches and derived data. The demo app runs fine, but adding it to my own project won't work somehow. Am I missing something?

[kostub]

Thanks for the clear report — this is a real bug, not something on your end.

It's a header-path issue that only affects downstream SPM consumers. The public header render/MTMathUILabel.h imports MTMathList.h, which actually lives in lib/, by bare filename. That only resolves via a header search path that's applied when building iosMath's own sources — so the bundled demo and the package's own tests work. But when your project builds the iosMath Clang module from the package's module map, that internal search path isn't present, so the include fails with 'MTMathList.h' file not found. (Xcode 16's explicit-modules dependency scanning is what surfaces it as the error you saw.) Clearing caches wouldn't help.

Fix is in #217: the cross-directory imports are path-qualified (lib/MTMathList.h) so they resolve from the package's public-headers root, which is exposed to consumers. I also added a regression test target that imports iosMath purely as a module with no internal search paths — i.e. exactly how your project consumes it — so this can't silently come back.

Once it's merged, please re-pull and let me know if it resolves things for you.

[Janneman84]

Thanks! It works now 🙂