[runtimes] Default LIB*_HERMETIC_STATIC_LIBRARY to ON on Windows

[mstorsjo]

Summary

(In the case of libunwind, the cmake option is called
LIBUNWIND_HIDE_SYMBOLS, but it has the same effect as
LIBCXX_HERMETIC_STATIC_LIBRARY and
LIBCXXABI_HERMETIC_STATIC_LIBRARY.)

Previously, the same issue was dealt with by setting a project wide
define (_LIBUNWIND_HIDE_SYMBOLS,
_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS and
_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS) if only building a static
library. If building both static and shared at the same time, this
wasn't set, and the static library would contain dllexport directives.

The LIB*_HERMETIC_STATIC_LIBRARY and LIBUNWIND_HIDE_SYMBOLS cmake
options only apply the defines to the static library in the build,
even if building both static and shared at the same time.

(This could only be done use after the object libraries were
enabled, as a shared libcxx needs libcxxabi object files built
with dllexports included.)

This allows removing inelegant code for deciding how to build the
libcxxabi static library and a TODO comment that suggested that
users should need to start setting an option, which they shouldn't
need to. Finally, this gets rid of two XFAILs in tests.

[phosek]

LGTM

[phosek]

We may also want to consider renaming LIBCXXABI_HERMETIC_STATIC_LIBRARY and LIBCXX_HERMETIC_STATIC_LIBRARY to LIBCXXABI_HIDE_SYMBOLS and LIBCXX_HIDE_SYMBOLS respectively for consistency.

libcxx/CMakeLists.txt

 
 set(LIBCXX_CONFIGURE_IDE_DEFAULT OFF)
 if (XCODE OR MSVC_IDE)
   set(LIBCXX_CONFIGURE_IDE_DEFAULT ON)
 endif()
 option(LIBCXX_CONFIGURE_IDE "Configure libcxx for use within an IDE"
       ${LIBCXX_CONFIGURE_IDE_DEFAULT})
 
+set(LIBCXX_HERMETIC_STATIC_LIBRARY_DEFAULT OFF)
+if (WIN32)
+  set(LIBCXX_HERMETIC_STATIC_LIBRARY_DEFAULT ON)
+endif()
 option(LIBCXX_HERMETIC_STATIC_LIBRARY
-  "Do not export any symbols from the static library." OFF)
+  "Do not export any symbols from the static library." ${LIBCXX_HERMETIC_STATIC_LIBRARY_DEFAULT})
 
 #===============================================================================
 # Check option configurations
 #===============================================================================
 
 # Ensure LIBCXX_ENABLE_MONOTONIC_CLOCK is set to ON only when
 # LIBCXX_ENABLE_THREADS is on.
 if(LIBCXX_ENABLE_THREADS AND NOT LIBCXX_ENABLE_MONOTONIC_CLOCK)

libcxx/src/CMakeLists.txt

if (LIBCXX_ENABLE_STATIC)
   if (LIBCXX_HERMETIC_STATIC_LIBRARY)
     # If the hermetic library doesn't define the operator new/delete functions
     # then its code shouldn't declare them with hidden visibility.  They might
     # actually be provided by a shared library at link time.
     if (LIBCXX_ENABLE_NEW_DELETE_DEFINITIONS)
       append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility-global-new-delete-hidden)
     endif()
     target_compile_options(cxx_static PRIVATE ${CXX_STATIC_LIBRARY_FLAGS})
-    target_compile_definitions(cxx_static PRIVATE _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
+    # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in __config_site
+    # too. Define it in the same way here, to avoid redefinition conflicts.
+    target_compile_definitions(cxx_static PRIVATE _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS=)
   endif()
 
   list(APPEND LIBCXX_BUILD_TARGETS "cxx_static")
   # Attempt to merge the libc++.a archive and the ABI library archive into one.
   if (LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY)
     target_link_libraries(cxx_static PRIVATE libcxx-abi-static-objects)
   endif()
 endif()

libcxx/test/libcxx/vendor/clang-cl/static-lib-exports.sh.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: msvc
 
 // This file checks that the built static library doesn't contain dllexport
 // directives in clang-cl builds.
 
 // RUN: llvm-readobj --coff-directives "%{lib}/libc++.lib" | not grep -i "export:" > /dev/null
-
-// It's a known issue, that when building a shared library at the same time
-// as the static library, the generated static library does contain dllexport
-// directives.
-// XFAIL: windows-dll

libcxx/test/libcxx/vendor/mingw/static-lib-exports.sh.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // REQUIRES: target={{.+}}-windows-gnu
 
 // This file checks that the built static library doesn't contain dllexport
 // directives in MinGW builds.
 
 // RUN: llvm-readobj --coff-directives "%{lib}/libc++.a" | not grep -i "export:" > /dev/null
-
-// It's a known issue, that when building a shared library at the same time
-// as the static library, the generated static library does contain dllexport
-// directives.
-// XFAIL: windows-dll

libcxxabi/CMakeLists.txt

if (NOT LIBCXXABI_ENABLE_SHARED AND NOT LIBCXXABI_ENABLE_STATIC)
   message(FATAL_ERROR "libc++abi must be built as either a shared or static library.")
 endif()
 
 # TODO: Remove this, which shouldn't be necessary since we know we're being built
 #       side-by-side with libc++.
 set(LIBCXXABI_LIBCXX_INCLUDES "" CACHE PATH
     "Specify path to libc++ includes.")
 
+set(LIBCXXABI_HERMETIC_STATIC_LIBRARY_DEFAULT OFF)
+if (WIN32)
+  set(LIBCXXABI_HERMETIC_STATIC_LIBRARY_DEFAULT ON)
+endif()
 option(LIBCXXABI_HERMETIC_STATIC_LIBRARY
-  "Do not export any symbols from the static library." OFF)
+  "Do not export any symbols from the static library." ${LIBCXXABI_HERMETIC_STATIC_LIBRARY_DEFAULT})
 
 set(LIBCXXABI_TEST_CONFIG "${CMAKE_CURRENT_SOURCE_DIR}/test/lit.site.cfg.in" CACHE STRING
   "The path to the Lit testing configuration to use when running the tests.
    If a relative path is provided, it is assumed to be relative to '<monorepo>/libcxxabi/test/configs'.")
 if (NOT IS_ABSOLUTE "${LIBCXXABI_TEST_CONFIG}")
   set(LIBCXXABI_TEST_CONFIG "${CMAKE_CURRENT_SOURCE_DIR}/test/configs/${LIBCXXABI_TEST_CONFIG}")
 endif()
 message(STATUS "Using libc++abi testing configuration: ${LIBCXXABI_TEST_CONFIG}")

 # Let the library headers know they are currently being used to build the
 # library.
 add_definitions(-D_LIBCXXABI_BUILDING_LIBRARY)
 
 # libcxxabi needs to, for various reasons, include the libcpp headers as if
 # it is being built as part of libcxx.
 add_definitions(-D_LIBCPP_BUILDING_LIBRARY)
 
-# Disable DLL annotations on Windows for static builds.
-if (WIN32 AND LIBCXXABI_ENABLE_STATIC AND NOT LIBCXXABI_ENABLE_SHARED)
-  # If LIBCXX_ENABLE_SHARED isn't set (by the user on the cmake command
-  # line or via a cache file), use its expected default value (enabled).
-  if ((LIBCXX_ENABLE_SHARED OR NOT DEFINED LIBCXX_ENABLE_SHARED) AND LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
-    # Building libcxxabi statically, but intending for it to be statically
-    # linked into a shared libcxx; keep dllexport enabled within libcxxabi,
-    # as the symbols will need to be exported from libcxx.
-  else()
-    # Regular static build; disable dllexports.
-    add_definitions(-D_LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS)
-    if (NOT LIBCXXABI_HERMETIC_STATIC_LIBRARY)
-      # TODO: Enable this warning message as soon as we're sure this is the solution.
-      # message(WARNING "Implicitly disabling dllexport on Win32 is not supported anymore. Please build with "
-      #                 "LIBCXXABI_HERMETIC_STATIC_LIBRARY=ON instead. This will become an error in LLVM 16.")
-    endif()
-  endif()
-endif()
-
 add_compile_flags_if_supported(-Werror=return-type)
 
 # Get warning flags
 add_compile_flags_if_supported(-W)
 add_compile_flags_if_supported(-Wall)
 add_compile_flags_if_supported(-Wchar-subscripts)
 add_compile_flags_if_supported(-Wconversion)
 add_compile_flags_if_supported(-Wmismatched-tags)

libcxxabi/src/CMakeLists.txt

 if(LIBCXXABI_HERMETIC_STATIC_LIBRARY)
   target_add_compile_flags_if_supported(cxxabi_static_objects PRIVATE -fvisibility=hidden)
   # If the hermetic library doesn't define the operator new/delete functions
   # then its code shouldn't declare them with hidden visibility.  They might
   # actually be provided by a shared library at link time.
   if (LIBCXXABI_ENABLE_NEW_DELETE_DEFINITIONS)
     target_add_compile_flags_if_supported(cxxabi_static_objects PRIVATE -fvisibility-global-new-delete-hidden)
   endif()
+  # _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS can be defined in libcxx's
+  # __config_site too. Define it in the same way here, to avoid redefinition
+  # conflicts.
   target_compile_definitions(cxxabi_static_objects
     PRIVATE
       _LIBCXXABI_DISABLE_VISIBILITY_ANNOTATIONS
-      _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS)
+      _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS=)
 endif()
 
 if (LIBCXXABI_ENABLE_STATIC)
   add_library(cxxabi_static STATIC)
   if (LIBCXXABI_USE_LLVM_UNWINDER AND NOT LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY)
     target_link_libraries(cxxabi_static PUBLIC unwind_static)
   endif()
   set_target_properties(cxxabi_static

libunwind/CMakeLists.txt

 if (NOT LIBUNWIND_ENABLE_SHARED AND NOT LIBUNWIND_ENABLE_STATIC)
   message(FATAL_ERROR "libunwind must be built as either a shared or static library.")
 endif()
 
 if (LIBUNWIND_ENABLE_CET AND MSVC)
   message(FATAL_ERROR "libunwind CET support is not available for MSVC!")
 endif()
 
+if (WIN32)
+  set(LIBUNWIND_DEFAULT_HIDE_SYMBOLS TRUE)
+else()
+  set(LIBUNWIND_DEFAULT_HIDE_SYMBOLS FALSE)
+endif()
 option(LIBUNWIND_HIDE_SYMBOLS
-  "Do not export any symbols from the static library." OFF)
+  "Do not export any symbols from the static library." ${LIBUNWIND_DEFAULT_HIDE_SYMBOLS})
 
 #===============================================================================
 # Configure System
 #===============================================================================
 
 # Add path for custom modules
 set(CMAKE_MODULE_PATH
     "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
if(LIBUNWIND_REMEMBER_HEAP_ALLOC)
   add_compile_definitions(_LIBUNWIND_REMEMBER_HEAP_ALLOC)
 endif()
 
 # This is the _ONLY_ place where add_definitions is called.
 if (MSVC)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
 endif()
 
-# Disable DLL annotations on Windows for static builds.
-if (WIN32 AND LIBUNWIND_ENABLE_STATIC AND NOT LIBUNWIND_ENABLE_SHARED)
-  add_definitions(-D_LIBUNWIND_HIDE_SYMBOLS)
-endif()
-
 if (C_SUPPORTS_COMMENT_LIB_PRAGMA)
   if (LIBUNWIND_HAS_DL_LIB)
     add_definitions(-D_LIBUNWIND_LINK_DL_LIB)
   endif()
   if (LIBUNWIND_HAS_PTHREAD_LIB)
     add_definitions(-D_LIBUNWIND_LINK_PTHREAD_LIB)
   endif()
 endif()