pkgs/os-specific/darwin/gen-frameworks.py

   1 #!/usr/bin/env nix-shell
   2 #!nix-shell -i python -p python3 swiftPackages.swift-unwrapped
   3
   4 """
   5 Generate a frameworks.nix for a macOS SDK.
   6
   7 You may point this tool at an Xcode bundled SDK, but more ideal is using the
   8 SDK from Nixpkgs. For example:
   9
  10 SDK_PATH="$(nix-build --no-link -A darwin.apple_sdk_11_0.MacOSX-SDK)"
  11 ./gen-frameworks.py "$SDK_PATH" > ./new-frameworks.nix
  12 """
  13
  14 import json
  15 import os
  16 import subprocess
  17 import sys
  18
  19 ALLOWED_LIBS = ["simd"]
  20
  21 HEADER = """\
  22 # This file is generated by gen-frameworks.nix.
  23 # Do not edit, put overrides in apple_sdk.nix instead.
  24 { libs, frameworks }: with libs; with frameworks;
  25 {
  26 """
  27
  28 FOOTER = """\
  29 }
  30 """
  31
  32
  33 def eprint(*args):
  34     print(*args, file=sys.stderr)
  35
  36
  37 def name_from_ident(ident):
  38     return ident.get("swift", ident.get("clang"))
  39
  40
  41 def scan_sdk(sdk):
  42     # Find frameworks by scanning the SDK frameworks directory.
  43     frameworks = [
  44         framework.removesuffix(".framework")
  45         for framework in os.listdir(f"{sdk}/System/Library/Frameworks")
  46         if not framework.startswith("_")
  47     ]
  48     frameworks.sort()
  49
  50     # Determine the longest name for padding output.
  51     width = len(max(frameworks, key=len))
  52
  53     output = HEADER
  54
  55     for framework in frameworks:
  56         deps = []
  57
  58         # Use Swift to scan dependencies, because a module may have both Clang
  59         # and Swift parts. Using Clang only imports the Clang module, whereas
  60         # using Swift will usually import both Clang + Swift overlay.
  61         #
  62         # TODO: The above is an assumption. Not sure if it's possible a Swift
  63         # module completely shadows a Clang module. (Seems unlikely)
  64         #
  65         # TODO: Handle "module 'Foobar' is incompatible with feature 'swift'"
  66         #
  67         # If there were a similar Clang invocation for scanning, we could fix
  68         # the above todos, but that doesn't appear to exist.
  69         eprint(f"# scanning {framework}")
  70         result = subprocess.run(
  71             [
  72                 "swiftc",
  73                 "-scan-dependencies",
  74                 # We provide a source snippet via stdin.
  75                 "-",
  76                 # Use the provided SDK.
  77                 "-sdk",
  78                 sdk,
  79                 # This search path is normally added automatically by the
  80                 # compiler based on the SDK, but we have a patch in place that
  81                 # removes that for SDKs in /nix/store, because our xcbuild stub
  82                 # SDK doesn't have the directory.
  83                 # (swift-prevent-sdk-dirs-warning.patch)
  84                 "-I",
  85                 f"{sdk}/usr/lib/swift",
  86                 # For some reason, 'lib/swift/shims' from both the SDK and
  87                 # Swift compiler are picked up, causing redefinition errors.
  88                 # This eliminates the latter.
  89                 "-resource-dir",
  90                 f"{sdk}/usr/lib/swift",
  91             ],
  92             input=f"import {framework}".encode(),
  93             stdout=subprocess.PIPE,
  94         )
  95         if result.returncode != 0:
  96             eprint(f"# Scanning {framework} failed (exit code {result.returncode})")
  97             result.stdout = b""
  98
  99         # Parse JSON output.
 100         if len(result.stdout) != 0:
 101             data = json.loads(result.stdout)
 102
 103             # Entries in the modules list come in pairs. The first is an
 104             # identifier (`{ swift: "foobar" }` or `{ clang: "foobar" }`), and
 105             # the second metadata for that module. Here we look for the pair
 106             # that matches the framework we're scanning (and ignore the rest).
 107             modules = data["modules"]
 108             for i in range(0, len(modules), 2):
 109                 ident, meta = modules[i : i + 2]
 110
 111                 # NOTE: We may match twice, for a Swift module _and_ for a
 112                 # Clang module. So matching here doesn't break from the loop,
 113                 # and deps is appended to.
 114                 if name_from_ident(ident) == framework:
 115                     dep_idents = meta["directDependencies"]
 116                     deps += [name_from_ident(ident) for ident in dep_idents]
 117                     # List unfiltered deps in progress output.
 118                     eprint(ident, "->", dep_idents)
 119
 120         # Filter out modules that are not separate derivations.
 121         # Also filter out duplicates (when a Swift overlay imports the Clang module)
 122         allowed = frameworks + ALLOWED_LIBS
 123         deps = set([dep for dep in deps if dep in allowed])
 124
 125         # Filter out self-references. (Swift overlay importing Clang module.)
 126         if framework in deps:
 127             deps.remove(framework)
 128
 129         # Generate a Nix attribute line.
 130         if len(deps) != 0:
 131             deps = list(deps)
 132             deps.sort()
 133             deps = " ".join(deps)
 134             output += f"  {framework.ljust(width)} = {{ inherit {deps}; }};\n"
 135         else:
 136             output += f"  {framework.ljust(width)} = {{}};\n"
 137
 138     output += FOOTER
 139     sys.stdout.write(output)
 140
 141
 142 if __name__ == "__main__":
 143     if len(sys.argv) != 2:
 144         eprint(f"Usage: {sys.argv[0]} <path to MacOSX.sdk>")
 145         sys.exit(64)
 146
 147     scan_sdk(sys.argv[1])