Xcode new build system debugging tricks

xcbuild-debugging-tricks.md

New Build System Tricks

Command Line

alias xcbuild=$(xcode-select -p)/../SharedFrameworks/XCBuild.framework/Versions/A/Support/xcbuild
# THIS DOESNT WORK YET: xcbuild openIDEConsole  # … then switch to Xcode ➡️
xcbuild showSpecs
xcbuild build <foo.pif> [—target <target>]

# Some minimal additional logging (this is safe to leave on).
defaults write com.apple.dt.XCBuild EnableDebugActivityLogs -bool YES

# Enable build debugging mode (safe to leave on, but slows down the build system & litters DerivedData/<project>/Build/Intermediates.noindex), generally should only be enabled when trying to capture a trace for incremental build debugging purposes.
defaults write com.apple.dt.XCBuild EnableBuildDebugging -bool YES
# You can also use:
env EnableBuildDebugging=YES xcodebuild -UseNewBuildSystem=1 ...

# Use `xcbuild` to dump a headermap.
xcbuild headermap --dump <path>

IDE Console

open with Internal > XCBuild Console

writePIF <workspace name> <path>
        # … you can use this with the `xcbuild build …` command (above) to build via the service directly
showStatistics
clearAllCaches
setConfig EnableBuildDebugging true
	# … then save DerivedData & build log; same as above dwrite, but not persisted

I guess there is no easy way to directly use llbuild to build an iOS project, right?

No, you have to build through XCBuild, via Xcode.

@ddunbar thanks for sharing this.
I use xcspec files to look for execpaths so that I can override them for my customisations.
For example,
ExecPath = "$(SWIFT_EXEC)" in Swift.xcspec

I'm trying to figure out how to prevent the build system from trying to use discovered dependency file (.d) next.
To prevent the following error.

error: unable to open dependencies file

Any clue how can I make sure of xcspec files above to find what I need?