"The compiler is unable to type-check this expression..."

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Created 3w

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"/Users/rich/Work/IdeaBlitz/IdeaBlitz/IdeaListView.swift:30:25 The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions"

Is it just me? I get this on syntax errors, missing commas, missing quotes, and for no particular reason at all that I can see. I don't think I've been able to write a single, simple, SwiftUI view without seeing this multiple times.

"Breaking it up" just makes it harder to read. Simple, inline, 2-page views become 8-page, totally unreadable, monstrosities.

Am I doing something wrong? Or is this just the state of SwiftUI today? Or is there some way to tell the compiler to take more time on this expression? I mean, if these can be broken up automatically, then why doesn't the compiler to that already?

Answered by DTS Engineer in 849906022

it is not a compile error but a run time error

The unable to type-check this expression in reasonable time error is most definitely a compile-time error.

People commonly bump into it in the context of SwiftUI, but that’s just because SwiftUI heavily leans into type inference. It’s possible to get this error in any Swift code.

This is a pretty common issue, and I spent some time writing up my thoughts it in a previous thread.

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Answer 1

Claude31 OP

3w

Is it something new to Xcode 26 or are you using Xcode 16 ?

You're right, that's a pretty common issue with SwiftUI and the pain is that there is not hint where the "error" precisely is.

That's intrinsic to how SwiftUI works (it is not a compile error but a run time error).

In some cases, just adding an element in an addition can cause the problem.

I do not usually break it up. A common issue is with arithmetic expressions: always make sure that the type of each value is explicit.

To localise the error, I go by dichotomy. I comment out half of the suspect part of code. If it works, problem is likely form the commented out. Otherwise, I comment half of the remaining part, and so on until I get to a single line.

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Answer 2

DTS Engineer OP

Apple

3w

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