Revert "Revert "CMake: Move sphinx detection into AddSphinxTarget.cmake""

This reverts commit r302054.

Re-commit now that I have fixes for clang/lld.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302499 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/config-ix.cmake

@@ -530,16 +530,6 @@ else()
   message(STATUS "Doxygen disabled.")
 endif()
 
-if (LLVM_ENABLE_SPHINX)
-  message(STATUS "Sphinx enabled.")
-  find_package(Sphinx REQUIRED)
-  if (LLVM_BUILD_DOCS)
-    add_custom_target(sphinx ALL)
-  endif()
-else()
-  message(STATUS "Sphinx disabled.")
-endif()
-
 set(LLVM_BINDINGS "")
 if(WIN32)
   message(STATUS "Go bindings disabled.")

cmake/modules/AddSphinxTarget.cmake

@@ -1,3 +1,16 @@
+
+# Create sphinx target
+if (LLVM_ENABLE_SPHINX AND NOT TARGET sphinx)
+  message(STATUS "Sphinx enabled.")
+  find_package(Sphinx REQUIRED)
+  if (LLVM_BUILD_DOCS)
+    add_custom_target(sphinx ALL)
+  endif()
+else()
+  message(STATUS "Sphinx disabled.")
+endif()
+
+
 # Handy function for creating the different Sphinx targets.
 #
 # ``builder`` should be one of the supported builders used by

docs/CMakeLists.txt

@@ -103,8 +103,8 @@ endif()
 endif()
 
 if (LLVM_ENABLE_SPHINX)
+  include(AddSphinxTarget)
   if (SPHINX_FOUND)
-    include(AddSphinxTarget)
     if (${SPHINX_OUTPUT_HTML})
       add_sphinx_target(html llvm)
     endif()