[Build System: build-script] Moved SWIFT_SOURCE_ROOT, SWIFT_BUILD_ROOT and SWIFT_REPO_NAME along with other project path constants into a new build_swift.constants module.

Author: Ross Bayer

utils/build-parser-lib

@@ -30,14 +30,13 @@ import os
 import platform
 import sys
 
-from build_swift.build_swift import argparse, defaults
+from build_swift.build_swift import argparse
+from build_swift.build_swift import defaults
+from build_swift.build_swift.constants import SWIFT_BUILD_ROOT
+from build_swift.build_swift.constants import SWIFT_SOURCE_ROOT
 from build_swift.build_swift.wrappers import xcrun
 
 from swift_build_support.swift_build_support import shell
-from swift_build_support.swift_build_support.SwiftBuildSupport import (
-    SWIFT_BUILD_ROOT,
-    SWIFT_SOURCE_ROOT,
-)
 from swift_build_support.swift_build_support.toolchain import host_toolchain
 
 isDarwin = platform.system() == "Darwin"

utils/build-script

@@ -28,32 +28,29 @@ from build_swift.build_swift import defaults
 from build_swift.build_swift import driver_arguments
 from build_swift.build_swift import migration
 from build_swift.build_swift import presets
+from build_swift.build_swift.constants import BUILD_SCRIPT_IMPL_PATH
+from build_swift.build_swift.constants import SWIFT_BUILD_ROOT
+from build_swift.build_swift.constants import SWIFT_REPO_NAME
+from build_swift.build_swift.constants import SWIFT_SOURCE_ROOT
 
 import six
 
 from swift_build_support.swift_build_support import products
 from swift_build_support.swift_build_support import shell
 from swift_build_support.swift_build_support import targets
 from swift_build_support.swift_build_support import workspace
-from swift_build_support.swift_build_support.SwiftBuildSupport import (
-    HOME,
-    SWIFT_BUILD_ROOT,
-    SWIFT_REPO_NAME,
-    SWIFT_SOURCE_ROOT,
-)
 from swift_build_support.swift_build_support.cmake import CMake
 from swift_build_support.swift_build_support.host_specific_configuration \
     import HostSpecificConfiguration
-from swift_build_support.swift_build_support.targets import \
-    StdlibDeploymentTarget
+from swift_build_support.swift_build_support.targets import StdlibDeploymentTarget
 from swift_build_support.swift_build_support.toolchain import host_toolchain
 
 
 # -----------------------------------------------------------------------------
 # Constants
 
-BUILD_SCRIPT_IMPL = os.path.join(
-    SWIFT_SOURCE_ROOT, SWIFT_REPO_NAME, "utils", "build-script-impl")
+# TODO: Remove this constant, it's really not helpful.
+HOME = os.environ.get("HOME", "/")
 
 
 # -----------------------------------------------------------------------------
@@ -839,7 +836,7 @@ class BuildScriptInvocation(object):
         # `build-script-impl`.
         if self.args.legacy_impl:
             # Execute the underlying build script implementation.
-            shell.call_without_sleeping([BUILD_SCRIPT_IMPL] + self.impl_args,
+            shell.call_without_sleeping([BUILD_SCRIPT_IMPL_PATH] + self.impl_args,
                                         env=self.impl_env, echo=True)
             return
 
@@ -961,7 +958,7 @@ class BuildScriptInvocation(object):
 
     def _execute_action(self, action_name):
         shell.call_without_sleeping(
-            [BUILD_SCRIPT_IMPL] + self.impl_args +
+            [BUILD_SCRIPT_IMPL_PATH] + self.impl_args +
             ["--only-execute", action_name],
             env=self.impl_env, echo=self.args.verbose_build)
 
@@ -1142,7 +1139,7 @@ def main_normal():
         # If we received any impl args, check if `build-script-impl` would
         # accept them or not before any further processing.
         try:
-            migration.check_impl_args(BUILD_SCRIPT_IMPL,
+            migration.check_impl_args(BUILD_SCRIPT_IMPL_PATH,
                                       args.build_script_impl_args)
         except ValueError as e:
             exit_rejecting_arguments(e, parser)

utils/build_swift/build_swift/constants.py

@@ -0,0 +1,205 @@
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
+# Licensed under Apache License v2.0 with Runtime Library Exception
+#
+# See https://swift.org/LICENSE.txt for license information
+# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
+
+from __future__ import absolute_import
+from __future__ import print_function
+from __future__ import unicode_literals
+
+import os.path
+
+
+__all__ = [
+    "BUILD_SCRIPT_IMPL_PATH",
+    "BUILD_SCRIPT_PATH",
+    "BUILD_SWIFT_PATH",
+    "MODULE_PATH",
+    "MULTIROOT_DATA_FILE_PATH",
+    "PROJECT_PATH",
+    "RESOURCES_PATH",
+    "SWIFT_BUILD_ROOT",
+    "SWIFT_REPO_NAME",
+    "SWIFT_SOURCE_ROOT",
+    "UTILS_PATH",
+]
+
+
+# --------------------------------------------------------------------------------------
+# Project Paths
+
+
+MODULE_PATH = os.path.abspath(os.path.dirname(__file__))
+
+BUILD_SWIFT_PATH = os.path.dirname(MODULE_PATH)
+
+UTILS_PATH = os.path.dirname(BUILD_SWIFT_PATH)
+
+PROJECT_PATH = os.path.dirname(UTILS_PATH)
+
+
+BUILD_SCRIPT_PATH = os.path.join(UTILS_PATH, "build-script")
+
+BUILD_SCRIPT_IMPL_PATH = os.path.join(UTILS_PATH, "build-script-impl")
+
+
+# --------------------------------------------------------------------------------------
+# Resources
+
+
+RESOURCES_PATH = os.path.join(BUILD_SWIFT_PATH, "resources")
+
+
+# The path to the Xcode workspace to use for a unified build of multiple SwiftPM
+# projects.
+MULTIROOT_DATA_FILE_PATH = os.path.join(
+    RESOURCES_PATH, "SwiftPM-Unified-Build.xcworkspace"
+)
+
+
+# --------------------------------------------------------------------------------------
+# Helpers
+
+
+def _is_llvm_checkout(llvm_path):
+    """Returns true if the given llvm_path is a valid LLVM checkout, false otherwise.
+
+    NOTE: This is a very naive validation, checking only for the existence of a few
+    known files.
+    """
+
+    if not os.path.exists(os.path.join(llvm_path, "tools")):
+        return False
+
+    if not os.path.exists(os.path.join(llvm_path, "CMakeLists.txt")):
+        return False
+
+    return True
+
+
+def _is_swift_checkout(swift_path):
+    """Returns true if the given swift_path is a valid Swift checkout, false otherwise.
+
+    NOTE: This is a very naive validation, checking only for the existence of a few
+    known files.
+    """
+
+    if not os.path.exists(os.path.join(swift_path, "utils")):
+        return False
+
+    if not os.path.exists(os.path.join(swift_path, "CMakeLists.txt")):
+        return False
+
+    return True
+
+
+def _get_swift_source_root(swift_path, env=None):
+    """Returns the Swift source root or None if one cannot be determined.
+
+    Users are able to manually override the source root by setting the SWIFT_SOURCE_ROOT
+    environment variable. If that cannot be found then this function will check the
+    directory structure to infer if we are building as a standalone Swift build or if we
+    are building in the unified LLVM.
+
+    Building standalone means Swift will be checked out as a peer of LLVM and the
+    enclosing directory is the source root.
+
+        source-root/
+        |- llvm/
+        |- swift/
+        | ...
+
+    However the unified case means Swift will be checked out in the llvm/tools
+    directory, which means the directory containing LLVM is the source root.
+
+        source-root/
+        |- llvm/
+        |   |- tools/
+        |   |   |- swift/
+        |   |   | ...
+        |   | ...
+        | ...
+
+    In the case that this function is called with an invalid Swift checkout it returns
+    None as well.
+
+    FIXME: What about the new llvm-project monorepo?
+    """
+
+    env = env or {}
+
+    # Check the environment first.
+    if "SWIFT_SOURCE_ROOT" in env:
+        return env["SWIFT_SOURCE_ROOT"]
+
+    # Assert we are in a valid Swift checkout.
+    if not _is_swift_checkout(swift_path):
+        return None
+
+    source_root = os.path.dirname(swift_path)
+
+    # Check if Swift is checked out as part of a unified build.
+    if os.path.basename(source_root) != "tools":
+        return source_root
+
+    llvm_path = os.path.dirname(source_root)
+    if not _is_llvm_checkout(llvm_path):
+        return source_root
+
+    # Return the directory containing LLVM.
+    return os.path.dirname(llvm_path)
+
+
+def _get_swift_build_root(source_root, env=None):
+    """Returns the Swift build root.
+
+    Users are able to manually override the build root by setting the SWIFT_BUILD_ROOT
+    environment variable. If that cannot be found then this function returns the path
+    to a directory named "build" in the given source root.
+    """
+
+    env = env or {}
+
+    if "SWIFT_BUILD_ROOT" in env:
+        return env["SWIFT_BUILD_ROOT"]
+
+    return os.path.join(source_root, "build")
+
+
+def _get_swift_repo_name(swift_path, env=None):
+    """Returns the Swift repo name or None if it cannot be determined.
+
+    Users are able to manually override the repo name by setting the SWIFT_REPO_NAME
+    environment variable. If that cannot be found then this function returns the name
+    of the given swift path or None if it is not a valid Swift checkout.
+    """
+
+    env = env or {}
+
+    if "SWIFT_REPO_NAME" in env:
+        return env["SWIFT_REPO_NAME"]
+
+    if not _is_swift_checkout(swift_path):
+        return None
+
+    return os.path.basename(swift_path)
+
+
+# --------------------------------------------------------------------------------------
+# Swift Source and Build Roots
+
+
+# Set SWIFT_SOURCE_ROOT in your environment to control where the sources are found.
+SWIFT_SOURCE_ROOT = _get_swift_source_root(PROJECT_PATH, env=os.environ)
+
+# Set SWIFT_BUILD_ROOT to a directory that will contain a subdirectory for each build
+# configuration
+SWIFT_BUILD_ROOT = _get_swift_build_root(SWIFT_SOURCE_ROOT, env=os.environ)
+
+# Set SWIFT_REPO_NAME in your environment to control the name of the swift directory
+# name that is used.
+SWIFT_REPO_NAME = _get_swift_repo_name(PROJECT_PATH, env=os.environ)