Inspect the Active Xcode Toolchain — xcode-toolchain • macrtools

Report which developer directory is active, whether a compiler can actually be reached through it, and which toolchains are available to switch to.

Usage

developer_dir()

is_xcode_toolchain_usable()

xcode_toolchains()

Value

The active developer directory, or NA_character_ when nothing usable is selected.

TRUE if a usable compiler is reachable, FALSE otherwise

A data frame with one row per selectable developer directory and columns path, type ("cli" or "app"), version and active.

Details

developer_dir() resolves the active developer directory. DEVELOPER_DIR overrides the selection stored by xcode-select, for xcrun, the /usr/bin shims and xcodebuild alike, so it is consulted first. Note that xcode-select --print-path echoes its value and exits 0 even when the directory does not exist, so the exit status alone proves nothing; the path is verified before being returned.

This is the question that matters for building R packages. R is configured with a bare clang, which resolves to the /usr/bin shim, so whether a package can be compiled depends on the active developer directory dispatching successfully, not on where the tools live.

xcrun --find clang resolves through the active directory and honors DEVELOPER_DIR. It can, however, exit 0 while printing an error for a degraded bundle, so the returned path is confirmed to exist and be executable rather than trusting the exit status.

Listing the Available Toolchains

xcode_toolchains() reports every developer directory xcode-select could be pointed at: the Command Line Tools, plus each installed Xcode bundle wherever it lives. Pass a path from this table to xcode_cli_switch().

Note that this lists developer directories, not .xctoolchain bundles. Those are a separate axis selected through xcrun --toolchain and the TOOLCHAINS variable, and are mostly Swift snapshots.

Examples

# Which developer directory is active
developer_dir()
#> [1] "/Applications/Xcode_26.6.app/Contents/Developer"
# Check whether a compiler is actually reachable
is_xcode_toolchain_usable()
#> [1] TRUE
# List every toolchain xcode-select could use
xcode_toolchains()
#>                                                path type             version
#> 1 /Applications/Xcode_26.0.1.app/Contents/Developer  app              26.0.1
#> 2 /Applications/Xcode_26.1.1.app/Contents/Developer  app              26.1.1
#> 3   /Applications/Xcode_26.2.app/Contents/Developer  app                26.2
#> 4   /Applications/Xcode_26.3.app/Contents/Developer  app                26.3
#> 5 /Applications/Xcode_26.4.1.app/Contents/Developer  app              26.4.1
#> 6   /Applications/Xcode_26.5.app/Contents/Developer  app                26.5
#> 7   /Applications/Xcode_26.6.app/Contents/Developer  app                26.6
#> 8               /Library/Developer/CommandLineTools  cli 26.6.0.0.1781586589
#>   active
#> 1  FALSE
#> 2  FALSE
#> 3  FALSE
#> 4  FALSE
#> 5  FALSE
#> 6  FALSE
#> 7   TRUE
#> 8  FALSE