[libcxx] Simplify the conditions for building libcxx

utils/build-presets.ini

@@ -717,6 +717,7 @@ llbuild
 swiftpm
 xctest
 libicu
+libcxx
 
 dash-dash
 
@@ -1034,6 +1035,7 @@ swiftsyntax
 skstresstester
 swiftevolve
 playgroundsupport
+libcxx
 
 # Build with debug info, this allows us to symbolicate crashes from
 # production builds.

utils/build-script

@@ -599,6 +599,8 @@ 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:
@@ -841,7 +843,8 @@ class BuildScriptInvocation(object):
         product_classes = []
         product_classes.append(products.CMark)
         product_classes.append(products.LLVM)
-        product_classes.append(products.LibCXX)
+        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

@@ -129,6 +129,7 @@ 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"
@@ -1203,6 +1204,7 @@ FOUNDATION_STATIC_SOURCE_DIR="${WORKSPACE}/swift-corelibs-foundation"
 LIBDISPATCH_SOURCE_DIR="${WORKSPACE}/swift-corelibs-libdispatch"
 LIBDISPATCH_STATIC_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 ${PLAYGROUNDSUPPORT_SOURCE_DIR} ]]; then
@@ -1237,12 +1239,6 @@ if [ -e "${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)

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

@@ -69,6 +69,7 @@
     'build_linux': True,
     'build_llbuild': False,
     'build_lldb': False,
+    'build_libcxx': False,
     'build_ninja': False,
     'build_osx': True,
     'build_playgroundsupport': False,
@@ -397,6 +398,7 @@ 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)