[libc++] Remove cmake glob for source files

[smeenai]

Summary

Globbing for source files is problematic because if a source file is
added or removed, the configuration won't be run again, and so the build
won't pick up on the added or removed file until the next configuration.
cmake's help explicitly recommends against the use of file(GLOB) to
collect a list of source files for the same reason. Switch to an
explicit list of files.

The glob for headers is left intact, partly because there are a ton of
them (courtesy of using GLOB_RECURSE), and partly because it shouldn't
affect building, since the header dependency tracking is handled
separately by cmake.

[EricWF]

Thanks for fixing this. Sucks that we have to manually enumerate source files but this is the correct solution according to CMake.

Would it be easy to still use glob to verify that none of the source files have accidentally been forgotten?

lib/CMakeLists.txt

321–323

These globs should be fixed as well.

[beanz]

LLVM has a CMake module "LLVMProcessSources.cmake" which verifies that all source files are referenced in the CMakeLists file. Since it is part of the LLVM distributed modules, you can re-use it in libcxx.

[smeenai]

I like the idea of verifying that all source files have been included. Will amend this accordingly. Thanks for the cmake pointer @beanz!

lib/CMakeLists.txt

321–323

Right, I missed this one.

[smeenai]

Address comments

[smeenai]

This depends on D37859 for the SOURCE_DIR parameter to llvm_check_source_file_list.

[smeenai]

@rjmccall, this adds a libc++ build dependency on LLVM's cmake modules. There were some issues when @zturner had added a similar dependency for his work on lit. To confirm, Apple still cares about the use case of building libc++ without having any LLVM cmake modules available (either from source or from an LLVM installation), right?

[rjmccall]

I'll let Duncan answer that question.

[beanz]

Building libcxx without LLVM's CMake modules is very important, not just to Apple. This is how several open source distributions work, and it would be a huge disservice to break this. Same is true for compiler-rt, libcxxabi, libunwind, etc.

Historically we've been drawing the line that building and running tests for runtime projects can require LLVM, but building the runtime libraries themselves must work without LLVM. I believe that is still the correct line to draw.

[dexonsmith]

In D31363#889044, @smeenai wrote:

@rjmccall, this adds a libc++ build dependency on LLVM's cmake modules. There were some issues when @zturner had added a similar dependency for his work on lit. To confirm, Apple still cares about the use case of building libc++ without having any LLVM cmake modules available (either from source or from an LLVM installation), right?

We resolved our need for building libcxx without llvm during the monorepo transition (2019).

[ldionne]

This patch isn't necessary anymore, as we don't use globing anymore. Let's abandon it to clean up the review queue.

[ldionne]

In D31363#2360132, @ldionne wrote:

This patch isn't necessary anymore, as we don't use globing anymore. Let's abandon it to clean up the review queue.

Actually, I misspoke. We still use it, but only in a few places. If you still feel that we should fix this, please rebase onto master and I will review. Otherwise, let's close this review.

benchmarks/CMakeLists.txt

set_target_properties(${native_target}
           LINK_FLAGS "${BENCHMARK_TEST_NATIVE_LINK_FLAGS}")
   endif()
 endmacro()
 
 
 #==============================================================================
 # Register Benchmark tests
 #==============================================================================
-file(GLOB BENCHMARK_TESTS "*.bench.cpp")
+include(LLVMProcessSources)
+set(BENCHMARK_TESTS
+      algorithms.bench.cpp
+      filesystem.bench.cpp
+      string.bench.cpp
+      stringstream.bench.cpp
+      unordered_set_operations.bench.cpp
+      util_smartptr.bench.cpp
+      vector_operations.bench.cpp)
+llvm_check_source_file_list(${BENCHMARK_TESTS})
 foreach(test_path ${BENCHMARK_TESTS})
   get_filename_component(test_file "${test_path}" NAME)
   string(REPLACE ".bench.cpp" "" test_name "${test_file}")
   if (NOT DEFINED ${test_name}_REPORTED)
     message(STATUS "Adding Benchmark: ${test_file}")
     # Only report the adding of the benchmark once.
     set(${test_name}_REPORTED ON CACHE INTERNAL "")
   endif()
   add_benchmark_test(${test_name} ${test_file})
 endforeach()

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)
+include(LLVMProcessSources)
+set(LIBCXX_SOURCES
+      ../src/algorithm.cpp
+      ../src/any.cpp
+      ../src/bind.cpp
+      ../src/chrono.cpp
+      ../src/condition_variable.cpp
+      ../src/debug.cpp
+      ../src/exception.cpp
+      ../src/functional.cpp
+      ../src/future.cpp
+      ../src/hash.cpp
+      ../src/ios.cpp
+      ../src/iostream.cpp
+      ../src/locale.cpp
+      ../src/memory.cpp
+      ../src/mutex.cpp
+      ../src/new.cpp
+      ../src/optional.cpp
+      ../src/random.cpp
+      ../src/regex.cpp
+      ../src/shared_mutex.cpp
+      ../src/stdexcept.cpp
+      ../src/string.cpp
+      ../src/strstream.cpp
+      ../src/system_error.cpp
+      ../src/thread.cpp
+      ../src/typeinfo.cpp
+      ../src/utility.cpp
+      ../src/valarray.cpp
+      ../src/variant.cpp
+      ../src/vector.cpp)
+llvm_check_source_file_list(${LIBCXX_SOURCES} SOURCE_DIR ../src)
 if(WIN32)
-  file(GLOB LIBCXX_WIN32_SOURCES ../src/support/win32/*.cpp)
+  set(LIBCXX_WIN32_SOURCES
+        ../src/support/win32/locale_win32.cpp
+        ../src/support/win32/support.cpp)
+  llvm_check_source_file_list(${LIBCXX_WIN32_SOURCES} SOURCE_DIR ../src/support/win32)
   list(APPEND LIBCXX_SOURCES ${LIBCXX_WIN32_SOURCES})
 elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "SunOS")
-  file(GLOB LIBCXX_SOLARIS_SOURCES ../src/support/solaris/*.cpp)
+  set(LIBCXX_SOLARIS_SOURCES
+        ../src/support/solaris/xlocale.cpp)
+  llvm_check_source_file_list(${LIBCXX_SOLARIS_SOURCES} SOURCE_DIR ../src/support/solaris)
   list(APPEND LIBCXX_SOURCES ${LIBCXX_SOLARIS_SOURCES})
 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)
if (LIBCXX_ENABLE_STATIC_ABI_LIBRARY)
     )
   endif()
 endif()
 
 # Add a meta-target for both libraries.
 add_custom_target(cxx DEPENDS ${LIBCXX_TARGETS})
 
 if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
-  file(GLOB LIBCXX_EXPERIMENTAL_SOURCES ../src/experimental/*.cpp)
+  set(LIBCXX_EXPERIMENTAL_SOURCES
+        ../src/experimental/memory_resource.cpp)
+  llvm_check_source_file_list(${LIBCXX_EXPERIMENTAL_SOURCES} SOURCE_DIR ../src/experimental)
   if (LIBCXX_ENABLE_FILESYSTEM)
-    file(GLOB LIBCXX_FILESYSTEM_SOURCES ../src/experimental/filesystem/*.cpp)
+    set(LIBCXX_FILESYSTEM_SOURCES
+          ../src/experimental/filesystem/directory_iterator.cpp
+          ../src/experimental/filesystem/operations.cpp
+          ../src/experimental/filesystem/path.cpp)
+    llvm_check_source_file_list(${LIBCXX_FILESYSTEM_SOURCES} SOURCE_DIR ../src/experimental/filesystem)
   endif()
   add_library(cxx_experimental STATIC ${LIBCXX_EXPERIMENTAL_SOURCES} ${LIBCXX_FILESYSTEM_SOURCES})
   if (LIBCXX_ENABLE_SHARED)
     target_link_libraries(cxx_experimental cxx_shared)
   else()
     target_link_libraries(cxx_experimental cxx_static)
   endif()