Allow disabling of filesystem library.

[EricWF]

Summary

Filesystem doesn't work on Windows, so we need a mechanism to turn it off for the time being.

[mstorsjo]

Looks sensible to me, modulo the option description.

CMakeLists.txt

80 ↗

(On Diff #191594)

This option text is a bit misleading (there's no separate libc++fs.a any longer if I understand it correctly) now.

[EricWF]

CMakeLists.txt

80 ↗

(On Diff #191594)

Woops. Thanks for catching that.

[EricWF]

• Correct a typo.

[EricWF]

Accepting for post-commit review.

We need to unbreak downsteam users.

[ldionne]

libcxx/trunk/utils/libcxx/test/config.py

438

Instead, I think this should be dependent on the platform. I don't see a reason why this would be different from` dylib-has-no-filesystem`.

[EricWF]

libcxx/trunk/utils/libcxx/test/config.py

438

That information is specified at configure time and the build system should respect that choice. I see no value auto-magically detecting it here. If they don't want it to run, they should disable it at configure time.

[ldionne]

libcxx/trunk/utils/libcxx/test/config.py

438

The way I see things, the lit test suite is disjoint from the CMake build configuration. When we run the lit test suite, we run it against a concrete release of the standard library (i.e. release by a vendor shipping the library). It just happens to be very convenient to pretend that libc++-as-shipped-with-LLVM is something that makes sense to test against because it gives us a sane workflow. This is why I'd rather not use switches to turn this-or-that on/off, but instead have the test suite know about various implementation characteristics and work with that.

In other words, instead of saying c++filesystem-disabled, just don't build filesystem into the dylib, and then have a way of telling the test suite that the library you're testing (libc++ trunk without filesystem support) has no support for filesystem.

[ldionne]

Eric and I spoke and we agreed on a way to handle disabling subparts of the test suite.

libcxx/trunk/CMakeLists.txt

 include(CMakeDependentOption)
 include(HandleCompilerRT)
 
 # Basic options ---------------------------------------------------------------
 option(LIBCXX_ENABLE_ASSERTIONS "Enable assertions independent of build mode." OFF)
 option(LIBCXX_ENABLE_SHARED "Build libc++ as a shared library." ON)
 option(LIBCXX_ENABLE_STATIC "Build libc++ as a static library." ON)
 option(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY "Build libc++experimental.a" ON)
+set(ENABLE_FILESYSTEM_DEFAULT ON)
+if (WIN32)
+  set(ENABLE_FILESYSTEM_DEFAULT OFF)
+endif()
+option(LIBCXX_ENABLE_FILESYSTEM "Build filesystem as part of the main libc++ library"
+    ${ENABLE_FILESYSTEM_DEFAULT})
 option(LIBCXX_INCLUDE_TESTS "Build the libc++ tests." ${LLVM_INCLUDE_TESTS})
 
 # Benchmark options -----------------------------------------------------------
 option(LIBCXX_INCLUDE_BENCHMARKS "Build the libc++ benchmarks and their dependencies" ON)
 
 set(LIBCXX_BENCHMARK_TEST_ARGS_DEFAULT --benchmark_min_time=0.01)
 set(LIBCXX_BENCHMARK_TEST_ARGS "${LIBCXX_BENCHMARK_TEST_ARGS_DEFAULT}" CACHE STRING
     "Arguments to pass when running the benchmarks using check-cxx-benchmarks")

libcxx/trunk/docs/BuildingLibcxx.rst

.. option:: LIBCXX_HERMETIC_STATIC_LIBRARY:BOOL
 
   **Default**: ``OFF``
 
   Do not export any symbols from the static libc++ library. This is useful when
   This is useful when the static libc++ library is being linked into shared
   libraries that may be used in with other shared libraries that use different
   C++ library. We want to avoid avoid exporting any libc++ symbols in that case.
 
+.. option:: LIBCXX_ENABLE_FILESYSTEM:BOOL
+
+   **Default**: ``ON`` except on Windows.
+
+   This option can be used to enable or disable the filesystem components on
+   platforms that may not support them. For example on Windows.
+
 .. _libc++experimental options:
 
 libc++experimental Specific Options
 ------------------------------------
 
 .. option:: LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY:BOOL
 
   **Default**: ``ON``

libcxx/trunk/lib/CMakeLists.txt

 set(LIBCXX_LIB_CMAKEFILES_DIR "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}"  PARENT_SCOPE)
 
 # Get sources
 # FIXME: Don't use glob here
 file(GLOB LIBCXX_SOURCES ../src/*.cpp)
-list(APPEND LIBCXX_SOURCES ../src/filesystem/operations.cpp
-                           ../src/filesystem/directory_iterator.cpp)
 if(WIN32)
   file(GLOB LIBCXX_WIN32_SOURCES ../src/support/win32/*.cpp)
   list(APPEND LIBCXX_SOURCES ${LIBCXX_WIN32_SOURCES})
 elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "SunOS")
   file(GLOB LIBCXX_SOLARIS_SOURCES ../src/support/solaris/*.cpp)
   list(APPEND LIBCXX_SOURCES ${LIBCXX_SOLARIS_SOURCES})
 endif()
 
+if (LIBCXX_ENABLE_FILESYSTEM)
+  list(APPEND LIBCXX_SOURCES ../src/filesystem/operations.cpp
+                             ../src/filesystem/directory_iterator.cpp)
   # Filesystem uses __int128_t, which requires a definition of __muloi4 when
   # compiled with UBSAN. This definition is not provided by libgcc_s, but is
   # provided by compiler-rt. So we need to disable it to avoid having multiple
   # definitions. See filesystem/int128_builtins.cpp.
   if (NOT LIBCXX_USE_COMPILER_RT)
     list(APPEND LIBCXX_SOURCES ../src/filesystem/int128_builtins.cpp)
   endif()
+endif()
 
 # Add all the headers to the project for IDEs.
 if (LIBCXX_CONFIGURE_IDE)
   file(GLOB_RECURSE LIBCXX_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/../include/*)
   if(WIN32)
     file( GLOB LIBCXX_WIN32_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/../include/support/win32/*.h)
     list(APPEND LIBCXX_HEADERS ${LIBCXX_WIN32_HEADERS})
   endif()

libcxx/trunk/test/CMakeLists.txt

 if (LIBCXX_ENABLE_ABI_LINKER_SCRIPT)
   set(LIBCXXABI_USE_LLVM_UNWINDER OFF)
 endif()
 
 pythonize_bool(LIBCXX_ENABLE_EXCEPTIONS)
 pythonize_bool(LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
 pythonize_bool(LIBCXX_ENABLE_RTTI)
 pythonize_bool(LIBCXX_ENABLE_SHARED)
+pythonize_bool(LIBCXX_ENABLE_FILESYSTEM)
 pythonize_bool(LIBCXX_BUILD_32_BITS)
 pythonize_bool(LIBCXX_GENERATE_COVERAGE)
 pythonize_bool(LIBCXXABI_ENABLE_SHARED)
 pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
 pythonize_bool(LIBCXX_USE_COMPILER_RT)
 pythonize_bool(LIBCXX_HAS_ATOMIC_LIB)
 pythonize_bool(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB)
 pythonize_bool(LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)

libcxx/trunk/test/libcxx/input.output/filesystems/lit.local.cfg

 # Disable all of the filesystem tests if the dylib under test doesn't support them.
 if 'dylib-has-no-filesystem' in config.available_features:
   config.unsupported = True
+if 'c++filesystem-disabled' in config.available_features:
+  config.unsupported = True

libcxx/trunk/test/lit.site.cfg.in

 @AUTO_GEN_COMMENT@
 config.cxx_under_test           = "@LIBCXX_COMPILER@"
 config.project_obj_root         = "@CMAKE_BINARY_DIR@"
 config.libcxx_src_root          = "@LIBCXX_SOURCE_DIR@"
 config.libcxx_obj_root          = "@LIBCXX_BINARY_DIR@"
 config.cxx_library_root         = "@LIBCXX_LIBRARY_DIR@"
 config.enable_exceptions        = @LIBCXX_ENABLE_EXCEPTIONS@
 config.enable_experimental      = @LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY@
+config.enable_filesystem        = @LIBCXX_ENABLE_FILESYSTEM@
 config.enable_rtti              = @LIBCXX_ENABLE_RTTI@
 config.enable_shared            = @LIBCXX_ENABLE_SHARED@
 config.enable_32bit             = @LIBCXX_BUILD_32_BITS@
 config.cxx_abi                  = "@LIBCXX_CXX_ABI_LIBNAME@"
 config.use_sanitizer            = "@LLVM_USE_SANITIZER@"
 config.sanitizer_library        = "@LIBCXX_SANITIZER_LIBRARY@"
 config.abi_library_path         = "@LIBCXX_CXX_ABI_LIBRARY_PATH@"
 config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"

libcxx/trunk/test/std/input.output/filesystems/lit.local.cfg

 # Disable all of the filesystem tests if the dylib under test doesn't support them.
 if 'dylib-has-no-filesystem' in config.available_features:
   config.unsupported = True
+if 'c++filesystem-disabled' in config.available_features:
+  config.unsupported = True
+

libcxx/trunk/utils/libcxx/test/config.py

def configure_features(self):
             # Default to running long tests.
             self.long_tests = True
             self.lit_config.note(
                 "inferred long_tests as: %r" % self.long_tests)
 
         if self.long_tests:
             self.config.available_features.add('long_tests')
 
+        if not self.get_lit_bool('enable_filesystem', default=True):
+            self.config.available_features.add('c++filesystem-disabled')
+
         # Run a compile test for the -fsized-deallocation flag. This is needed
         # in test/std/language.support/support.dynamic/new.delete
         if self.cxx.hasCompileFlag('-fsized-deallocation'):
             self.config.available_features.add('-fsized-deallocation')
 
         if self.cxx.hasCompileFlag('-faligned-allocation'):
             self.config.available_features.add('-faligned-allocation')
         else: