[libcxx] Simplify the conditions for building libcxx

Now we build libcxx if and only if --libcxx is passed, like with other
optional products.  This loses the intended "build if sources are
checked out" behaviour, but behaves more predictably.

(cherry picked from commit e180006)

Revert "Revert "[build-script] Add Product for libc++""

add libcxx-cmake-options

Author: benlangmuir

utils/build-presets.ini

@@ -717,6 +717,7 @@ llbuild
 swiftpm
 xctest
 libicu
+libcxx
 
 dash-dash
 
@@ -730,6 +731,7 @@ install-libicu
 install-prefix=/usr
 swift-install-components=autolink-driver;compiler;clang-resource-dir-symlink;stdlib;swift-remote-mirror;sdk-overlay;license;sourcekit-inproc
 llvm-install-components=llvm-cov;llvm-profdata;IndexStore;clang;clang-headers;compiler-rt
+install-libcxx
 build-swift-static-stdlib
 build-swift-static-sdk-overlay
 build-swift-stdlib-unittest-extra

utils/build-script

@@ -586,6 +586,8 @@ class BuildScriptInvocation(object):
             impl_args += ["--skip-build-lldb"]
         if not args.build_llbuild:
             impl_args += ["--skip-build-llbuild"]
+        if not args.build_libcxx:
+            impl_args += ["--skip-build-libcxx"]
         if not args.build_libdispatch:
             impl_args += ["--skip-build-libdispatch"]
         if not args.build_libicu:
@@ -823,6 +825,8 @@ class BuildScriptInvocation(object):
         product_classes = []
         product_classes.append(products.CMark)
         product_classes.append(products.LLVM)
+        if self.args.build_libcxx:
+            product_classes.append(products.LibCXX)
         if self.args.build_libicu:
             product_classes.append(products.LibICU)
         product_classes.append(products.Swift)

utils/build-script-impl

@@ -123,6 +123,7 @@ KNOWN_SETTINGS=(
     skip-build-android          ""               "set to skip building Swift stdlibs for Android"
     skip-build-lldb             ""               "set to skip building LLDB"
     skip-build-llbuild          ""               "set to skip building llbuild"
+    skip-build-libcxx           ""               "set to skip building libcxx"
     skip-build-swiftpm          ""               "set to skip building swiftpm"
     skip-build-swiftsyntax      ""               "set to skip building swiftSyntax"
     skip-build-skstresstester   ""               "set to skip building the SourceKit stress tester"
@@ -199,6 +200,7 @@ KNOWN_SETTINGS=(
     install-skstresstester      ""               "whether to install the SourceKit stress tester"
     install-xctest              ""               "whether to install xctest"
     install-foundation          ""               "whether to install foundation"
+    install-libcxx              ""               "whether to install libc++"
     install-libdispatch         ""               "whether to install libdispatch"
     install-libicu              ""               "whether to install libicu"
     install-playgroundsupport   ""               "whether to install PlaygroundSupport"
@@ -255,6 +257,7 @@ KNOWN_SETTINGS=(
     swiftpm-cmake-options              ""        "CMake options used for all swiftpm targets"
     xctest-cmake-options               ""        "CMake options used for all xctest targets"
     playgroundsupport-cmake-options    ""        "CMake options used for all playgroundsupport targets"
+    libcxx-cmake-options               ""        "CMake options used for all libcxx targets"
     # TODO: Remove this some time later.
     user-config-args            ""               "**Renamed to --extra-cmake-options**: User-supplied arguments to cmake when used to do configuration."
     only-execute                       "all"     "Only execute the named action (see implementation)"
@@ -1180,6 +1183,7 @@ XCTEST_SOURCE_DIR="${WORKSPACE}/swift-corelibs-xctest"
 FOUNDATION_SOURCE_DIR="${WORKSPACE}/swift-corelibs-foundation"
 LIBDISPATCH_SOURCE_DIR="${WORKSPACE}/swift-corelibs-libdispatch"
 LIBICU_SOURCE_DIR="${WORKSPACE}/icu"
+LIBCXX_SOURCE_DIR="${WORKSPACE}/libcxx"
 PLAYGROUNDSUPPORT_SOURCE_DIR="${WORKSPACE}/swift-xcode-playground-support"
 
 if [[ ! "${SKIP_BUILD_PLAYGROUNDSUPPORT}" && ! -d ${PLAYGROUNDSUPPORT_SOURCE_DIR} ]]; then
@@ -1214,12 +1218,6 @@ if [ -e "${WORKSPACE}/compiler-rt" ] ; then
     fi
 fi
 
-# Build libcxx, unless it doesn't exist.
-LIBCXX_SOURCE_DIR="${WORKSPACE}/libcxx"
-if [[ ! -e "${LIBCXX_SOURCE_DIR}" ]] ; then
-  SKIP_BUILD_LIBCXX=1
-fi
-
 PRODUCTS=(cmark llvm)
 if [[ ! "${SKIP_BUILD_LIBCXX}" ]] ; then
      PRODUCTS=("${PRODUCTS[@]}" libcxx)
@@ -3446,6 +3444,9 @@ for host in "${ALL_HOSTS[@]}"; do
                 INSTALL_TARGETS=install-$(echo ${LLVM_INSTALL_COMPONENTS} | sed -E 's/;/ install-/g')
                 ;;
             libcxx)
+                if [[ -z "${INSTALL_LIBCXX}" ]] ; then
+                    continue
+                fi
                 INSTALL_TARGETS=install-cxx-headers
                 ;;
             swift)

utils/build_swift/driver_arguments.py

@@ -142,6 +142,7 @@ def _apply_default_arguments(args):
         args.build_external_benchmarks = False
         args.build_lldb = False
         args.build_llbuild = False
+        args.build_libcxx = False
         args.build_swiftpm = False
         args.build_xctest = False
         args.build_foundation = False
@@ -512,6 +513,9 @@ def create_argument_parser():
     option(['-b', '--llbuild'], store_true('build_llbuild'),
            help='build llbuild')
 
+    option(['--libcxx'], store_true('build_libcxx'),
+           help='build libcxx')
+
     option(['-p', '--swiftpm'], store_true('build_swiftpm'),
            help='build swiftpm')
 

utils/build_swift/tests/expected_options.py

@@ -67,6 +67,7 @@
     'build_linux': True,
     'build_llbuild': False,
     'build_lldb': False,
+    'build_libcxx': False,
     'build_ninja': False,
     'build_osx': True,
     'build_playgroundsupport': False,
@@ -393,6 +394,7 @@ class IgnoreOption(_BaseOption):
     SetTrueOption('--ios'),
     SetTrueOption('--llbuild', dest='build_llbuild'),
     SetTrueOption('--lldb', dest='build_lldb'),
+    SetTrueOption('--libcxx', dest='build_libcxx'),
     SetTrueOption('--playgroundsupport', dest='build_playgroundsupport'),
     SetTrueOption('--skip-build'),
     SetTrueOption('--swiftpm', dest='build_swiftpm'),

utils/build_swift/tests/test_driver_arguments.py

@@ -590,6 +590,7 @@ def test_implied_defaults_skip_build(self):
             self.assertFalse(namespace.build_libicu)
             self.assertFalse(namespace.build_lldb)
             self.assertFalse(namespace.build_llbuild)
+            self.assertFalse(namespace.build_libcxx)
             self.assertFalse(namespace.build_playgroundsupport)
             self.assertFalse(namespace.build_swiftpm)
             self.assertFalse(namespace.build_xctest)

utils/swift_build_support/swift_build_support/products/__init__.py

@@ -12,6 +12,7 @@
 
 from .cmark import CMark
 from .foundation import Foundation
+from .libcxx import LibCXX
 from .libdispatch import LibDispatch
 from .libicu import LibICU
 from .llbuild import LLBuild
@@ -26,6 +27,7 @@
     'CMark',
     'Ninja',
     'Foundation',
+    'LibCXX',
     'LibDispatch',
     'LibICU',
     'LLBuild',

utils/swift_build_support/swift_build_support/products/libcxx.py

@@ -0,0 +1,17 @@
+# swift_build_support/products/libcxx.py -------------------------*- python -*-
+#
+# This source file is part of the Swift.org open source project
+#
+# Copyright (c) 2014 - 2017 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 . import product
+
+
+class LibCXX(product.Product):
+    pass