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.

5 files changed, 36 insertions, 1 deletions

diff --git a/Tests/CMakeCommands/target_link_libraries/CMakeLists.txt b/Tests/CMakeCommands/target_link_libraries/CMakeLists.txt
index 60b36fc..29b69d9 100644
--- a/Tests/CMakeCommands/target_link_libraries/CMakeLists.txt
+++ b/Tests/CMakeCommands/target_link_libraries/CMakeLists.txt
@@ -53,6 +53,13 @@ set_target_properties(targetA PROPERTIES LINK_INTERFACE_LIBRARIES "")
 
 assert_property(targetA LINK_INTERFACE_LIBRARIES "")
 
+add_subdirectory(subdir)
+target_link_libraries(targetA subdirlib)
+set_property(TARGET targetA APPEND PROPERTY
+  INCLUDE_DIRECTORIES
+    $<TARGET_PROPERTY:subdirlib,INTERFACE_INCLUDE_DIRECTORIES>
+)
+
 target_link_libraries(targetA depB depC)
 
 assert_property(targetA LINK_INTERFACE_LIBRARIES "")
diff --git a/Tests/CMakeCommands/target_link_libraries/subdir/CMakeLists.txt b/Tests/CMakeCommands/target_link_libraries/subdir/CMakeLists.txt
new file mode 100644
index 0000000..61a1a59
--- /dev/null
+++ b/Tests/CMakeCommands/target_link_libraries/subdir/CMakeLists.txt
@@ -0,0 +1,5 @@
+
+set(CMAKE_BUILD_INTERFACE_INCLUDES ON)
+
+add_library(subdirlib SHARED subdirlib.cpp)
+generate_export_header(subdirlib)
diff --git a/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.cpp b/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.cpp
new file mode 100644
index 0000000..cd2f1a2
--- /dev/null
+++ b/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.cpp
@@ -0,0 +1,7 @@
+
+#include "subdirlib.h"
+
+int SubDirLibObject::foo() const
+{
+  return 0;
+}
diff --git a/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.h b/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.h
new file mode 100644
index 0000000..e386f87
--- /dev/null
+++ b/Tests/CMakeCommands/target_link_libraries/subdir/subdirlib.h
@@ -0,0 +1,12 @@
+
+#ifndef SUBDIRLIB_H
+#define SUBDIRLIB_H
+
+#include "subdirlib_export.h"
+
+struct SUBDIRLIB_EXPORT SubDirLibObject
+{
+  int foo() const;
+};
+
+#endif
diff --git a/Tests/CMakeCommands/target_link_libraries/targetA.cpp b/Tests/CMakeCommands/target_link_libraries/targetA.cpp
index 6ff65b1..559aef7 100644
--- a/Tests/CMakeCommands/target_link_libraries/targetA.cpp
+++ b/Tests/CMakeCommands/target_link_libraries/targetA.cpp
@@ -3,6 +3,8 @@
 #include "depC.h"
 #include "depIfaceOnly.h"
 
+#include "subdirlib.h"
+
 int main(int argc, char **argv)
 {
   DepA a;
@@ -11,5 +13,7 @@ int main(int argc, char **argv)
 
   DepIfaceOnly iface_only;
 
-  return a.foo() + b.foo() + c.foo() + iface_only.foo();
+  SubDirLibObject sd;
+
+  return a.foo() + b.foo() + c.foo() + iface_only.foo() + sd.foo();
 }