[PATCH] Teach llvm_add_library() to search arbitrary directories for includes.

[Zachary Turner]

Hi chandlerc,

    Since header files are not compilation units, CMake does not require
    you to specify them in the CMakeLists.txt file.  As a result, unless
    a header file is explicitly added, CMake won't know about it, and
    when generating IDE-based projects, CMake won't put the header files
    into the IDE project.  LLVM currently tries to deal with this in two
    ways:

      1) It looks for all .h files that are in the project directory,
         and adds those.
      2) llvm_add_library() understands the ADDITIONAL_HEADERS argument,
         which allows one to list an arbitrary list of headers.

    This patch takes things one step further.  It adds the ability for
    llvm_add_library() to take an ADDITIONAL_HEADER_DIRS argument,
    which will specify a list of folders which CMake will glob for
    header files.  Furthermore, it will glob not only for .h files, but
    also for .inc files.

    Included in this CL is an update to one of the existing users of
    ADDITIONAL_HEADERS to use this new argument instead, to serve as an
    illustration of how this cleans up the CMake.

    The big advantage of this new approach is that until now, there was
    no way for the IDE projects to locate the header files that are in
    the include tree.  In other words, if you are in, for example,
    lib/DebugInfo/DWARF, the corresponding includes for this project
    will be located under include/DebugInfo/DWARF.  Now, in the
    CMakeLists.txt for lib/DebugInfo/DWARF, you can simply write:

      ADDITIONAL_HEADER_DIRS
      ../../include/DebugInfo/DWARF

    as an argument to llvm_add_library(), and all header files will get added to
    the IDE project.

http://reviews.llvm.org/D7460

Files:
  cmake/modules/LLVMProcessSources.cmake
  lib/Support/CMakeLists.txt

Index: cmake/modules/LLVMProcessSources.cmake
===================================================================
--- cmake/modules/LLVMProcessSources.cmake
+++ cmake/modules/LLVMProcessSources.cmake
@@ -28,26 +28,39 @@
   endif()
 endmacro(add_td_sources)
 
+function(add_header_files_for_glob hdrs_out glob)
+  file(GLOB hds ${glob})
+  set(${hdrs_out} ${hds} PARENT_SCOPE)
+endfunction(add_header_files_for_glob)
 
-macro(add_header_files srcs)
-  file(GLOB hds *.h)
-  if( hds )
-    set_source_files_properties(${hds} PROPERTIES HEADER_FILE_ONLY ON)
-    list(APPEND ${srcs} ${hds})
-  endif()
-endmacro(add_header_files)
+function(find_all_header_files hdrs_out additional_headerdirs)
+  add_header_files_for_glob(hds *.h)
+  list(APPEND all_headers ${hds})
+
+  foreach(additional_dir ${additional_headerdirs})
+    add_header_files_for_glob(hds "${additional_dir}/*.h")
+    list(APPEND all_headers ${hds})
+    add_header_files_for_glob(hds "${additional_dir}/*.inc")
+    list(APPEND all_headers ${hds})
+  endforeach(additional_dir)
+
+  set( ${hdrs_out} ${all_headers} PARENT_SCOPE )
+endfunction(find_all_header_files)
 
 
 function(llvm_process_sources OUT_VAR)
-  cmake_parse_arguments(ARG "" "" "ADDITIONAL_HEADERS" ${ARGN})
+  cmake_parse_arguments(ARG "" "" "ADDITIONAL_HEADERS;ADDITIONAL_HEADER_DIRS" ${ARGN})
   set(sources ${ARG_UNPARSED_ARGUMENTS})
   llvm_check_source_file_list( ${sources} )
   if( MSVC_IDE OR XCODE )
     # This adds .td and .h files to the Visual Studio solution:
     add_td_sources(sources)
-    add_header_files(sources)
+    find_all_header_files(hdrs "${ARG_ADDITIONAL_HEADER_DIRS}")
+    if (hdrs)
+      set_source_files_properties(${hdrs} PROPERTIES HEADER_FILE_ONLY ON)
+    endif()
     set_source_files_properties(${ARG_ADDITIONAL_HEADERS} PROPERTIES HEADER_FILE_ONLY ON)
-    list(APPEND sources ${ARG_ADDITIONAL_HEADERS})
+    list(APPEND sources ${ARG_ADDITIONAL_HEADERS} ${hdrs})
   endif()
 
   set( ${OUT_VAR} ${sources} PARENT_SCOPE )
Index: lib/Support/CMakeLists.txt
===================================================================
--- lib/Support/CMakeLists.txt
+++ lib/Support/CMakeLists.txt
@@ -121,30 +121,9 @@
   Valgrind.cpp
   Watchdog.cpp
 
-  ADDITIONAL_HEADERS
-  Unix/Host.inc
-  Unix/Memory.inc
-  Unix/Mutex.inc
-  Unix/Path.inc
-  Unix/Process.inc
-  Unix/Program.inc
-  Unix/RWMutex.inc
-  Unix/Signals.inc
-  Unix/ThreadLocal.inc
-  Unix/TimeValue.inc
-  Unix/Watchdog.inc
-  Windows/DynamicLibrary.inc
-  Windows/Host.inc
-  Windows/Memory.inc
-  Windows/Mutex.inc
-  Windows/Path.inc
-  Windows/Process.inc
-  Windows/Program.inc
-  Windows/RWMutex.inc
-  Windows/Signals.inc
-  Windows/ThreadLocal.inc
-  Windows/TimeValue.inc
-  Windows/Watchdog.inc
+  ADDITIONAL_HEADER_DIRS
+  Unix
+  Windows
 
   LINK_LIBS ${system_libs}
   )

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/
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