Add CMAKE_BUILD_INTERFACE_INCLUDES build-variable.

This makes

 set(CMAKE_BUILD_INTERFACE_INCLUDES ON)

add the equivalent of

 set_property(TARGET tgt APPEND PROPERTY
   INTERFACE_INCLUDE_DIRECTORIES
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR};${CMAKE_CURRENT_BINARY_DIR}>
 )

to every target.

If the headers are in CMAKE_CURRENT_SOURCE_DIR, and the generated headers
are in CMAKE_CURRENT_BINARY_DIR, this is a convenient way to build a target
bar, which depends on foo, just by using target_link_libraries() and adding
the INTERFACE_INCLUDE_DIRECTORIES to the INCLUDE_DIRECTORIES of the target
being linked. There will be more-convenient porcelain API to consume the
property in the future.

1 files changed, 11 insertions, 0 deletions

diff --git a/Source/cmDocumentVariables.cxx b/Source/cmDocumentVariables.cxx
index be45e2d..08b3ef1 100644
--- a/Source/cmDocumentVariables.cxx
+++ b/Source/cmDocumentVariables.cxx
@@ -1147,6 +1147,17 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      "Variables that Control the Build");
 
   cm->DefineProperty
+    ("CMAKE_BUILD_INTERFACE_INCLUDES", cmProperty::VARIABLE,
+     "Automatically add the current source- and build directories "
+     "to the INTERFACE_INCLUDE_DIRECTORIES.",
+     "If this variable is enabled, CMake automatically adds for each "
+     "target ${CMAKE_CURRENT_SOURCE_DIR} and ${CMAKE_CURRENT_BINARY_DIR} "
+     "to the INTERFACE_INCLUDE_DIRECTORIES."
+     "By default CMAKE_BUILD_INTERFACE_INCLUDES is OFF.",
+     false,
+     "Variables that Control the Build");
+
+  cm->DefineProperty
     ("CMAKE_INSTALL_RPATH", cmProperty::VARIABLE,
      "The rpath to use for installed targets.",
      "A semicolon-separated list specifying the rpath "