[build-script] Add installation support for sourcekit-lsp

When invoked with the `install` action, build-script-helper.py will
rsync the produced sourcekit-lsp to the toolchain's bin directory. On
Linux, we add an extra relative rpath to find the swift corelibs
(unfotunately we currently have no way to remove the absolute rpath; the
same is true for all other swift-built binaries in the toolchain). On
macOS, we replace the rpath.

Author: benlangmuir

Utilities/build-script-helper.py

@@ -29,18 +29,46 @@ def get_swiftpm_options(args):
   if args.verbose:
     swiftpm_args += ['--verbose']
 
-  if platform.system() != 'Darwin':
+  if platform.system() == 'Darwin':
+    swiftpm_args += [
+      # Relative library rpath for swift; will only be used when /usr/lib/swift
+      # is not available.
+      '-Xlinker', '-rpath', '-Xlinker', '@executable_path/../lib/swift/macosx',
+    ]
+  else:
     swiftpm_args += [
       # Dispatch headers
       '-Xcxx', '-I', '-Xcxx',
       os.path.join(args.toolchain, 'usr', 'lib', 'swift'),
       # For <Block.h>
       '-Xcxx', '-I', '-Xcxx',
       os.path.join(args.toolchain, 'usr', 'lib', 'swift', 'Block'),
+      # Library rpath for swift, dispatch, Foundation, etc. when installing
+      '-Xlinker', '-rpath', '-Xlinker', '$ORIGIN/../lib/swift/linux',
     ]
 
   return swiftpm_args
 
+def install(swiftpm_bin_path, toolchain):
+  toolchain_bin = os.path.join(toolchain, 'usr', 'bin')
+  for exe in ['sourcekit-lsp']:
+    install_binary(exe, swiftpm_bin_path, toolchain_bin, toolchain)
+
+def install_binary(exe, source_dir, install_dir, toolchain):
+  cmd = ['rsync', '-a', os.path.join(source_dir, exe), install_dir]
+  print(' '.join(cmd))
+  subprocess.check_call(cmd)
+
+  if platform.system() == 'Darwin':
+    result_path = os.path.join(install_dir, exe)
+    stdlib_rpath = os.path.join(toolchain, 'usr', 'lib', 'swift', 'macosx')
+    delete_rpath(stdlib_rpath, result_path)
+
+def delete_rpath(rpath, binary):
+  cmd = ["install_name_tool", "-delete_rpath", rpath, binary]
+  print(' '.join(cmd))
+  subprocess.check_call(cmd)
+
 def main():
   parser = argparse.ArgumentParser(description='Build along with the Swift build-script.')
   def add_common_args(parser):
@@ -58,6 +86,9 @@ def add_common_args(parser):
   test_parser = subparsers.add_parser('test', help='test the package')
   add_common_args(test_parser)
 
+  install_parser = subparsers.add_parser('install', help='build the package')
+  add_common_args(install_parser)
+
   args = parser.parse_args(sys.argv[1:])
 
   # Canonicalize paths
@@ -89,6 +120,10 @@ def add_common_args(parser):
     print('Cleaning ' + tests)
     shutil.rmtree(tests, ignore_errors=True)
     swiftpm('test', swift_exec, swiftpm_args, env)
+  elif args.action == 'install':
+    bin_path = swiftpm_bin_path(swift_exec, swiftpm_args, env)
+    swiftpm('build', swift_exec, swiftpm_args, env)
+    install(bin_path, args.toolchain)
   else:
     assert False, 'unknown action \'{}\''.format(args.action)