Applying @_transparent to a non-public non-@usableFromInline function crashes swift-frontend in release mode

[b8591340]

Note that this does not occur in new projects and packages, where the compilers correctly fails with the error.

It happened multiple times in a complex private package until I added @usableFromInline or public. The curious thing is that it built in debug mode for quite a while before I realized.

[slavapestov]

Do you have a test case? Note that @_transparent is really only intended for use by the standard library. You should use @inlinable instead.

[b8591340]

I don’t Slava—can’t share the package, sorry.

I see. I think I ended up moving to @_transparent once I realized it was compiled once and then incremental builds did not affect @_transparent function bodies even when changed.

Is it correct that it only affects the first debug build in compile times? Otherwise, if I may, what’s best for telling the compiler to always inline in release builds while retaining the highest possible debug build performance? Anecdotally @inlinable @inline(__always) seems to increase debug build times.