error: Could not compute dependency graph: Error Domain=NSPOSIXErrorDomain Code=86 "Bad CPU type in executable"

[torarnv]

When swift-build computes the dependency graph for a build it seems to resolve the toolchains available on the system, which may include tools that are x86_64 only. If Rosetta2 is not installed, this results in a hard-failure for every build in Xcode/xcodebuild on Apple Silicon system:

Installing Rosetta2, and then watching process creation via Process Monitor during a build shows:

{
  "event": "ES_EVENT_TYPE_NOTIFY_EXEC",
  "timestamp": "2025-10-02 09:39:14 +0000",
  "process": {
    "pid": 35254,
    "name": "qcc",
    "path": "/opt/qnx700/host/darwin/x86_64/usr/bin/qcc",
    "uid": 501,
    "architecture": "unknown",
    "arguments": [
      "/opt/qnx700/host/darwin/x86_64/usr/bin/qcc",
      "-dM",
      "E",
      "-x",
      "c",
      "-c",
      "/dev/null",
      "-o",
      "/dev/null"
    ],
    "ppid": 35253,
    "rpid": 34691,
    "ancestors": [
      34691,
      1
    ],
    "signing info (reported)": {
      "csFlags": 0,
      "platformBinary": 0,
      "signingID": "",
      "teamID": "",
      "cdHash": "0000000000000000000000000000000000000000"
    },
    "signing info (computed)": {
      "signatureStatus": -67062
    }
  }
}

With SWBBuildService as its parent process.

I don't know if there's any way to opt out of (specific) toolchain lookups?

In any case, the logic here for QNX, or possibly at a higher level, should probably handle the situation gracefully by treating it as the toolchain not found, possibly with an explicit warning, rather than the opaque "Bad CPU type in executable" with no info about which executable failed to run 😄

[torarnv]

CC @jakepetroules

[torarnv]

As a data point, renaming the qcc binary to qcc.nope results in:

$ xcodebuild
Command line invocation:
    /Applications/Xcode26_Universal.app/Contents/Developer/usr/bin/xcodebuild

ComputePackagePrebuildTargetDependencyGraph
error: Could not compute dependency graph: stat(/opt/qnx700/host/darwin/x86_64/usr/bin/qcc): No such file or directory (2)

** BUILD FAILED **


The following build commands failed:
	Compute target dependency graph for package preparation
(1 failure)

While renaming /opt/qnx700 results in a successful build.

[jakepetroules]

PRs are up to resolve the actual issue as well as improve the error output for future cases. Thanks for the debugging! As a workaround for now, renaming /opt/qnx700 aside seems like the best advice (or install Rosetta).

[torarnv]

Thanks @jakepetroules! 🎉 We haven't built QNX on macOS since Qt 5 times, so as a fix/workaround on our side I just removed QNX from provisioning: https://codereview.qt-project.org/c/qt/qt5/+/681536