Non-deterministic build systems results across language versions and platforms

[vsanthanam]

Description

Main and latest released version are the same commit on this repo at the moment (this is often the case), and platform support does not usually change between commits.

And yet, I get very odd results across versions of my library where random platforms are suddenly failing the build:

In this particular example, iOS is red on main but green on 2.3.0, even though these are literally the same commit (b48a03d)

Repro

This happens essentially anytime the build system is run, whether I land a commit or release a new version. The build system results are seemingly random.

Expected Behavior

Anytime the build system is run against this repo, I get non-deterministic failures. Sometimes a particular swift version and platform combination will fail, sometimes it will not. The GitHub actions associated with the repo build the project for all these platforms and more, and while I do not necessarily expect the SPM build system to mirror my configuration exactly, I do expect its failures to be predictable. A given Swift Version/Platform combination should not suddenly disappear on a commit and randomly reappear in the next commit. The same commit built twice should produce the same results.

[daveverwer]

Hi @vsanthanam and our apologies for the inconsistencies you're seeing here. I can confirm that the two builds you see different results for were built from the same commit, and that's not great.

From a quick look at the build logs, I think this is an intermittent auto-generated scheme issue:

2026-07-16 10:41:22.475 xcodebuild[1207:7831] Writing error result bundle to /var/folders/xq/y_g06wb113726d38xsyx71_h0000gn/T/ResultBundle_2026-16-07_10-41-0022.xcresult
xcodebuild: error: The workspace named "spi-builder-workspace" does not contain a scheme named "JBird-Package". The "-list" option can be used to find the names of the schemes in the workspace.

I agree this should be consistent, but rather than try and fight the scheme auto-generation, it might be best to set that scheme for all platforms. I see you have a custom scheme specifically for macOS in your .spi.yml file right now. Let's try this:

version: 1
builder:
  configs:
  - scheme: JBird
external_links:
  documentation: "https://www.usejbird.com/docs/documentation/jbird/"

[vsanthanam]

no apology necessary! I just wanted to flag the issue incase there is something bigger going on here. I am grateful for the free build capacity provided by the Swift Package Index 😊

I will try with an updated .spi.yml per your suggestion and see what happens.

[vsanthanam]

OK I pushed a change that removed the platform, but this seems to have caused new errors in the around certificate management and code signing: https://swiftpackageindex.com/builds/148006F1-A16C-4694-B749-FFE711E14FD4

[daveverwer]

I'm afraid these errors are not related to our build infrastructure as I can also reproduce them locally. At the top of the build log view that you referred to in your message, you'll see the "Build Command"

I just ran this same build command locally and got the same error. This points to it being something you should fix locally before pushing up. Good luck!