[lldb] Support specifying a custom libcxx for the API tests

[JDevlieghere]

Summary

D129166 was an attempt to ensure that by default we use the libc++ from the build dir instead of potentially picking up the system libc++. While I was reviewing D132257, I realized that part of the patch (i.e. the change to Makefile.rules) got lost. As I was reviving the code, I realized that it would be relatively straightforward to merge my change with what Felipe was trying to achieve. Instead of telling dotest to use the libc++ form the build dir and computing the path to the current build's libc++ (as was the case in D129166), we can specify the libc++ include and library dir to dotest (as was the case in D132257) and have lit compute the path to the libc++ in the build dir, achieving both objectives.

[fdeazeve]

Thanks for merging the two patches! This LGTM!

lldb/packages/Python/lldbsuite/test/builders/builder.py

def getModuleCacheSpec(self):
         module cache used for the make system.
         """
         if configuration.clang_module_cache_dir:
             return ["CLANG_MODULE_CACHE_DIR={}".format(
                 configuration.clang_module_cache_dir)]
         return []
 
     def getLibCxxArgs(self):
-        if configuration.hermetic_libcxx:
-            return ["USE_HERMETIC_LIBCPP=1"]
+        if configuration.libcxx_include_dir and configuration.libcxx_library_dir:
+            return ["LIBCPP_INCLUDE_DIR={}".format(configuration.libcxx_include_dir),
+                    "LIBCPP_LIBRARY_DIR={}".format(configuration.libcxx_library_dir)]
         return []
 
     def _getDebugInfoArgs(self, debug_info):
         if debug_info is None:
             return []
         if debug_info == "dwarf":
             return ["MAKE_DSYM=NO"]
         if debug_info == "dwo":

lldb/packages/Python/lldbsuite/test/configuration.py

 
 # The names of all tests. Used to assert we don't have two tests with the
 # same base name.
 all_tests = set()
 
 # LLDB library directory.
 lldb_libs_dir = None
 
-# Force us to use the just-built libcxx
-hermetic_libcxx = False
+libcxx_include_dir = None
+libcxx_library_dir = None
 
 # A plugin whose tests will be enabled, like intel-pt.
 enabled_plugins = []
 
 
 def shouldSkipBecauseOfCategories(test_categories):
     if use_categories:
         if len(test_categories) == 0 or len(

lldb/packages/Python/lldbsuite/test/dotest.py

def parseOptionsAndInitTestdirs():
     if args.llvm_tools_dir:
         configuration.filecheck = shutil.which("FileCheck", path=args.llvm_tools_dir)
         configuration.yaml2obj = shutil.which("yaml2obj", path=args.llvm_tools_dir)
 
     if not configuration.get_filecheck_path():
         logging.warning('No valid FileCheck executable; some tests may fail...')
         logging.warning('(Double-check the --llvm-tools-dir argument to dotest.py)')
 
-    configuration.hermetic_libcxx = args.hermetic_libcxx
-    if configuration.hermetic_libcxx and args.lldb_platform_name:
-        configuration.hermetic_libcxx = False
-        logging.warning('Hermetic libc++ is not supported for remote runs: ignoring --hermetic-libcxx')
+    configuration.libcxx_include_dir = args.libcxx_include_dir
+    configuration.libcxx_library_dir = args.libcxx_library_dir
+    if args.libcxx_include_dir or args.libcxx_library_dir:
+        if args.lldb_platform_name:
+            logging.warning('Custom libc++ is not supported for remote runs: ignoring --libcxx arguments')
+        elif args.libcxx_include_dir and args.libcxx_library_dir:
+            configuration.libcxx_include_dir = args.libcxx_include_dir
+            configuration.libcxx_library_dir = args.libcxx_library_dir
+        else:
+            logging.error('Custom libc++ requires both --libcxx-include-dir and --libcxx-library-dir')
+            sys.exit(-1)
 
     if args.channels:
         lldbtest_config.channels = args.channels
 
     if args.log_success:
         lldbtest_config.log_success = args.log_success
 
     if args.out_of_tree_debugserver:

lldb/packages/Python/lldbsuite/test/dotest_args.py

group.add_argument(
         metavar='arch',
         dest='arch',
         help=textwrap.dedent('''Specify the architecture(s) to test. This option can be specified more than once'''))
     group.add_argument('-C', '--compiler', metavar='compiler', dest='compiler', help=textwrap.dedent(
         '''Specify the compiler(s) used to build the inferior executables. The compiler path can be an executable basename or a full path to a compiler executable. This option can be specified multiple times.'''))
     if sys.platform == 'darwin':
         group.add_argument('--apple-sdk', metavar='apple_sdk', dest='apple_sdk', default="", help=textwrap.dedent(
             '''Specify the name of the Apple SDK (macosx, macosx.internal, iphoneos, iphoneos.internal, or path to SDK) and use the appropriate tools from that SDK's toolchain.'''))
-    group.add_argument('--hermetic-libcxx', action='store_true', help=textwrap.dedent(
-        '''Force the just-built libcxx to be used for the libc++ formatter tests.'''))
+    group.add_argument('--libcxx-include-dir', help=textwrap.dedent('Specify the path to a custom libc++ include directory. Must be used in conjunction with --libcxx-library-dir.'))
+    group.add_argument('--libcxx-library-dir', help=textwrap.dedent('Specify the path to a custom libc++ library directory. Must be used in conjunction with --libcxx-include-dir.'))
     # FIXME? This won't work for different extra flags according to each arch.
     group.add_argument(
         '-E',
         metavar='extra-flags',
         help=textwrap.dedent('''Specify the extra flags to be passed to the toolchain when building the inferior programs to be debugged
                                                            suggestions: do not lump the "-A arch1 -A arch2" together such that the -E option applies to only one of the architectures'''))
 
     group.add_argument('--dsymutil', metavar='dsymutil', dest='dsymutil', help=textwrap.dedent('Specify which dsymutil to use.'))

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

ifeq (1,$(USE_LIBSTDCPP))
   ifneq (,$(findstring clang,$(CC)))
     CXXFLAGS += -stdlib=libstdc++ -DLLDB_USING_LIBSTDCPP
     LDFLAGS += -stdlib=libstdc++
   endif
 endif
 
 ifeq (1,$(USE_LIBCPP))
   CXXFLAGS += -DLLDB_USING_LIBCPP
+  ifneq ($(and $(LIBCPP_INCLUDE_DIR), $(LIBCPP_LIBRARY_DIR)),)
+    CXXFLAGS += -nostdlib++ -nostdinc++ -cxx-isystem $(LIBCPP_INCLUDE_DIR)
+    LDFLAGS += -L$(LLVM_LIBS_DIR) -Wl,-rpath,$(LIBCPP_LIBRARY_DIR) -lc++
+  else
     ifeq "$(OS)" "Android"
         # Nothing to do, this is already handled in
         # Android.rules.
     else
         CXXFLAGS += -stdlib=libc++
         LDFLAGS += -stdlib=libc++
     endif
     ifneq (,$(filter $(OS), FreeBSD Linux NetBSD))
         ifneq (,$(LLVM_LIBS_DIR))
         LDFLAGS += -Wl,-rpath,$(LLVM_LIBS_DIR)
         endif
     endif
   endif
+endif
 
 #----------------------------------------------------------------------
 # Additional system libraries
 #----------------------------------------------------------------------
 ifeq (1,$(USE_LIBDL))
   ifeq (,$(filter $(OS), NetBSD Windows_NT))
     LDFLAGS += -ldl
   endif

lldb/test/API/lit.cfg.py

if is_configured('llvm_include_dir'):
   dotest_cmd += ['--env', 'LLVM_INCLUDE_DIR=' + config.llvm_include_dir]
 
 # This path may be needed to locate required llvm tools
 if is_configured('llvm_tools_dir'):
   dotest_cmd += ['--env', 'LLVM_TOOLS_DIR=' + config.llvm_tools_dir]
 
 # If we have a just-built libcxx, prefer it over the system one.
 if is_configured('has_libcxx') and platform.system() != 'Windows':
-  dotest_cmd += ['--hermetic-libcxx']
+  if is_configured('llvm_include_dir') and is_configured('llvm_libs_dir'):
+    dotest_cmd += ['--libcxx-include-dir', os.path.join(config.llvm_include_dir, 'c++', 'v1')]
+    dotest_cmd += ['--libcxx-library-dir', config.llvm_libs_dir]
 
 # Forward ASan-specific environment variables to tests, as a test may load an
 # ASan-ified dylib.
 for env_var in ('ASAN_OPTIONS', 'DYLD_INSERT_LIBRARIES'):
   if env_var in config.environment:
     dotest_cmd += ['--inferior-env', env_var + '=' + config.environment[env_var]]
 
 if is_configured('test_arch'):