bootstrap: Granular system library selection (#11431)

This adds the ability for packagers to specify that some libraries
should use system versions and others should use the CMake versions.

This allows a bit of flexibility and means Homebrew (an OSX package
manager) no longer has to continue to patch the CMake build process.

Inspired-by: Mike McQuaid <mike@mikemcquaid.com>

1 files changed, 39 insertions, 28 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4508e33e11..37e0edc4f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,12 @@ IF(COMMAND CMAKE_POLICY)
   CMAKE_POLICY(SET CMP0003 NEW)
 ENDIF(COMMAND CMAKE_POLICY)
 
+IF(CMAKE_BOOTSTRAP)
+  # Running from bootstrap script.  Set local variable and remove from cache.
+  SET(CMAKE_BOOTSTRAP 1)
+  UNSET(CMAKE_BOOTSTRAP CACHE)
+ENDIF()
+
 MARK_AS_ADVANCED(CMAKE_BACKWARDS_COMPATIBILITY)
 
 # Allow empty endif() and such with CMake 2.4.
@@ -53,42 +59,47 @@ MACRO(CMAKE_HANDLE_SYSTEM_LIBRARIES)
   OPTION(CTEST_USE_XMLRPC "Enable xmlrpc submission method in CTest." OFF)
   MARK_AS_ADVANCED(CTEST_USE_XMLRPC)
 
-  # Allow the user to enable/disable all system utility library options
-  # by setting CMAKE_USE_SYSTEM_LIBRARIES on the command line.
-  IF(DEFINED CMAKE_USE_SYSTEM_LIBRARIES)
-    SET(CMAKE_USE_SYSTEM_LIBRARIES_USER 1)
-  ENDIF(DEFINED CMAKE_USE_SYSTEM_LIBRARIES)
-  IF(CMAKE_USE_SYSTEM_LIBRARIES)
-    SET(CMAKE_USE_SYSTEM_LIBRARIES ON)
-  ELSE(CMAKE_USE_SYSTEM_LIBRARIES)
-    SET(CMAKE_USE_SYSTEM_LIBRARIES OFF)
-  ENDIF(CMAKE_USE_SYSTEM_LIBRARIES)
-  IF(CMAKE_USE_SYSTEM_LIBRARIES_USER)
-    SET(CMAKE_USE_SYSTEM_CURL "${CMAKE_USE_SYSTEM_LIBRARIES}"
-      CACHE BOOL "Use system-installed curl" FORCE)
-    SET(CMAKE_USE_SYSTEM_EXPAT "${CMAKE_USE_SYSTEM_LIBRARIES}"
-      CACHE BOOL "Use system-installed expat" FORCE)
-    SET(CMAKE_USE_SYSTEM_ZLIB "${CMAKE_USE_SYSTEM_LIBRARIES}"
-      CACHE BOOL "Use system-installed zlib" FORCE)
-    SET(CMAKE_USE_SYSTEM_BZIP2 "${CMAKE_USE_SYSTEM_LIBRARIES}"
-      CACHE BOOL "Use system-installed bzip2" FORCE)
-    SET(CMAKE_USE_SYSTEM_LIBARCHIVE "${CMAKE_USE_SYSTEM_LIBRARIES}"
-      CACHE BOOL "Use system-installed libarchive" FORCE)
-  ENDIF(CMAKE_USE_SYSTEM_LIBRARIES_USER)
+  # Allow the user to enable/disable all system utility library options by
+  # defining CMAKE_USE_SYSTEM_LIBRARIES or CMAKE_USE_SYSTEM_LIBRARY_${util}.
+  SET(UTILITIES BZIP2 CURL EXPAT LIBARCHIVE ZLIB)
+  FOREACH(util ${UTILITIES})
+    IF(NOT DEFINED CMAKE_USE_SYSTEM_LIBRARY_${util}
+        AND DEFINED CMAKE_USE_SYSTEM_LIBRARIES)
+      SET(CMAKE_USE_SYSTEM_LIBRARY_${util} "${CMAKE_USE_SYSTEM_LIBRARIES}")
+    ENDIF()
+    IF(DEFINED CMAKE_USE_SYSTEM_LIBRARY_${util})
+      IF(CMAKE_USE_SYSTEM_LIBRARY_${util})
+        SET(CMAKE_USE_SYSTEM_LIBRARY_${util} ON)
+      ELSE()
+        SET(CMAKE_USE_SYSTEM_LIBRARY_${util} OFF)
+      ENDIF()
+      IF(CMAKE_BOOTSTRAP)
+        UNSET(CMAKE_USE_SYSTEM_LIBRARY_${util} CACHE)
+      ENDIF()
+      STRING(TOLOWER "${util}" lutil)
+      SET(CMAKE_USE_SYSTEM_${util} "${CMAKE_USE_SYSTEM_LIBRARY_${util}}"
+        CACHE BOOL "Use system-installed ${lutil}" FORCE)
+    ELSE()
+      SET(CMAKE_USE_SYSTEM_LIBRARY_${util} OFF)
+    ENDIF()
+  ENDFOREACH(util)
+  IF(CMAKE_BOOTSTRAP)
+    UNSET(CMAKE_USE_SYSTEM_LIBRARIES CACHE)
+  ENDIF()
 
   # Optionally use system utility libraries.
-  OPTION(CMAKE_USE_SYSTEM_LIBARCHIVE "Use system-installed libarchive" ${CMAKE_USE_SYSTEM_LIBRARIES})
+  OPTION(CMAKE_USE_SYSTEM_LIBARCHIVE "Use system-installed libarchive" "${CMAKE_USE_SYSTEM_LIBRARY_LIBARCHIVE}")
   CMAKE_DEPENDENT_OPTION(CMAKE_USE_SYSTEM_CURL "Use system-installed curl"
-    ${CMAKE_USE_SYSTEM_LIBRARIES} "NOT CTEST_USE_XMLRPC" ON)
+    "${CMAKE_USE_SYSTEM_LIBRARY_CURL}" "NOT CTEST_USE_XMLRPC" ON)
   CMAKE_DEPENDENT_OPTION(CMAKE_USE_SYSTEM_EXPAT "Use system-installed expat"
-    ${CMAKE_USE_SYSTEM_LIBRARIES} "NOT CTEST_USE_XMLRPC" ON)
+    "${CMAKE_USE_SYSTEM_LIBRARY_EXPAT}" "NOT CTEST_USE_XMLRPC" ON)
   CMAKE_DEPENDENT_OPTION(CMAKE_USE_SYSTEM_ZLIB "Use system-installed zlib"
-    ${CMAKE_USE_SYSTEM_LIBRARIES} "NOT CMAKE_USE_SYSTEM_LIBARCHIVE;NOT CMAKE_USE_SYSTEM_CURL" ON)
+    "${CMAKE_USE_SYSTEM_LIBRARY_ZLIB}" "NOT CMAKE_USE_SYSTEM_LIBARCHIVE;NOT CMAKE_USE_SYSTEM_CURL" ON)
   CMAKE_DEPENDENT_OPTION(CMAKE_USE_SYSTEM_BZIP2 "Use system-installed bzip2"
-    ${CMAKE_USE_SYSTEM_LIBRARIES} "NOT CMAKE_USE_SYSTEM_LIBARCHIVE" ON)
+    "${CMAKE_USE_SYSTEM_LIBRARY_BZIP2}" "NOT CMAKE_USE_SYSTEM_LIBARCHIVE" ON)
 
   # Mention to the user what system libraries are being used.
-  FOREACH(util BZIP2 CURL EXPAT LIBARCHIVE ZLIB)
+  FOREACH(util ${UTILITIES})
     IF(CMAKE_USE_SYSTEM_${util})
       MESSAGE(STATUS "Using system-installed ${util}")
     ENDIF(CMAKE_USE_SYSTEM_${util})