OS X: Detect implicit linker framework search paths

Previously we hard-coded a list of implicit framework directories but
did not account for CMAKE_OSX_SYSROOT or for changes to the list across
OS X versions.  Instead we should automatically detect the framework
directories for the active toolchain.

The parent commit added the "-Wl,-v" option to ask "ld" to print its
implicit directories.  It displays a block such as:

 Framework search paths:
	/...

Parse this block to extract the list of framework directories.

Detection may fail on toolchains that do not list their framework
directories, such as older OS X linkers.  Always treat the paths

 <sdk>/Library/Frameworks
 <sdk>/System/Library/Frameworks
 <sdk>/Network/Library/Frameworks # Older OS X only
 /System/Library/Frameworks

as implicit.  Note that /System/Library/Frameworks should always be
considered implicit so that frameworks CMake finds there will not
override the SDK copies.

1 files changed, 26 insertions, 14 deletions

diff --git a/Modules/CMakeParseImplicitLinkInfo.cmake b/Modules/CMakeParseImplicitLinkInfo.cmake
index 54e8127..234fb7f 100644
--- a/Modules/CMakeParseImplicitLinkInfo.cmake
+++ b/Modules/CMakeParseImplicitLinkInfo.cmake
@@ -16,9 +16,10 @@
 # This is used internally by CMake and should not be included by user
 # code.
 
-function(CMAKE_PARSE_IMPLICIT_LINK_INFO text lib_var dir_var log_var obj_regex)
+function(CMAKE_PARSE_IMPLICIT_LINK_INFO text lib_var dir_var fwk_var log_var obj_regex)
   set(implicit_libs_tmp "")
   set(implicit_dirs_tmp)
+  set(implicit_fwks_tmp)
   set(log "")
 
   # Parse implicit linker arguments.
@@ -113,6 +114,11 @@ function(CMAKE_PARSE_IMPLICIT_LINK_INFO text lib_var dir_var log_var obj_regex)
     set(log "${log}  Library search paths: [${implicit_dirs_match}]\n")
     list(APPEND implicit_dirs_tmp ${implicit_dirs_match})
   endif()
+  if("${output_lines}" MATCHES ";Framework search paths:((;\t[^;]+)+)")
+    string(REPLACE ";\t" ";" implicit_fwks_match "${CMAKE_MATCH_1}")
+    set(log "${log}  Framework search paths: [${implicit_fwks_match}]\n")
+    list(APPEND implicit_fwks_tmp ${implicit_fwks_match})
+  endif()
 
   # Cleanup list of libraries and flags.
   # We remove items that are not language-specific.
@@ -125,27 +131,33 @@ function(CMAKE_PARSE_IMPLICIT_LINK_INFO text lib_var dir_var log_var obj_regex)
     endif()
   endforeach()
 
-  # Cleanup list of library directories.
-  set(implicit_dirs "")
-  foreach(d IN LISTS implicit_dirs_tmp)
-    get_filename_component(dir "${d}" ABSOLUTE)
-    string(FIND "${dir}" "${CMAKE_FILES_DIRECTORY}/" pos)
-    if(NOT pos LESS 0)
-      set(msg ", skipping non-system directory")
-    else()
-      set(msg "")
-      list(APPEND implicit_dirs "${dir}")
-    endif()
-    set(log "${log}  collapse library dir [${d}] ==> [${dir}]${msg}\n")
+  # Cleanup list of library and framework directories.
+  set(desc_dirs "library")
+  set(desc_fwks "framework")
+  foreach(t dirs fwks)
+    set(implicit_${t} "")
+    foreach(d IN LISTS implicit_${t}_tmp)
+      get_filename_component(dir "${d}" ABSOLUTE)
+      string(FIND "${dir}" "${CMAKE_FILES_DIRECTORY}/" pos)
+      if(NOT pos LESS 0)
+        set(msg ", skipping non-system directory")
+      else()
+        set(msg "")
+        list(APPEND implicit_${t} "${dir}")
+      endif()
+      set(log "${log}  collapse ${desc_${t}} dir [${d}] ==> [${dir}]${msg}\n")
+    endforeach()
+    list(REMOVE_DUPLICATES implicit_${t})
   endforeach()
-  list(REMOVE_DUPLICATES implicit_dirs)
 
   # Log results.
   set(log "${log}  implicit libs: [${implicit_libs}]\n")
   set(log "${log}  implicit dirs: [${implicit_dirs}]\n")
+  set(log "${log}  implicit fwks: [${implicit_fwks}]\n")
 
   # Return results.
   set(${lib_var} "${implicit_libs}" PARENT_SCOPE)
   set(${dir_var} "${implicit_dirs}" PARENT_SCOPE)
+  set(${fwk_var} "${implicit_fwks}" PARENT_SCOPE)
   set(${log_var} "${log}" PARENT_SCOPE)
 endfunction()