Create make rules for INTERFACE_LIBRARY targets.

The result is that the depends of the target are created.

So,

 add_library(somelib foo.cpp)
 add_library(anotherlib EXCLUDE_FROM_ALL foo.cpp)
 add_library(extra EXCLUDE_FROM_ALL foo.cpp)
 target_link_libraries(anotherlib extra)

 add_library(iface INTERFACE)
 target_link_libraries(iface INTERFACE anotherlib)

Executing 'make iface' will result in the anotherlib and extra targets
being made.

Adding a regular executable to the INTERFACE of an INTERFACE_LIBRARY
will not result in the executable being built with 'make iface' because
of the logic in cmComputeTargetDepends::AddTargetDepend.

So far, this is implemented only for the Makefile generator. Other
generators will follow if this feature is possible for them.

Make INTERFACE_LIBRARY targets part of the all target by default.
Test this by building the all target and making the expected library
EXCLUDE_FROM_ALL.

3 files changed, 23 insertions, 0 deletions

diff --git a/Tests/InterfaceBuildTargets/CMakeLists.txt b/Tests/InterfaceBuildTargets/CMakeLists.txt
new file mode 100644
index 0000000..a00e5d5
--- /dev/null
+++ b/Tests/InterfaceBuildTargets/CMakeLists.txt
@@ -0,0 +1,13 @@
+project(InterfaceBuildTargets)
+
+add_library(testlib EXCLUDE_FROM_ALL testlib.cxx)
+set_property(TARGET testlib PROPERTY PREFIX "")
+if(CMAKE_GENERATOR MATCHES "Borland|Watcom")
+  # These librarians add the .lib suffix anyway.
+  set_property(TARGET testlib PROPERTY SUFFIX ".lib")
+else()
+  set_property(TARGET testlib PROPERTY SUFFIX "")
+endif()
+
+add_library(iface INTERFACE)
+target_link_libraries(iface INTERFACE testlib)
diff --git a/Tests/InterfaceBuildTargets/main.cxx b/Tests/InterfaceBuildTargets/main.cxx
new file mode 100644
index 0000000..e9ad257
--- /dev/null
+++ b/Tests/InterfaceBuildTargets/main.cxx
@@ -0,0 +1,5 @@
+
+int main(int, char**)
+{
+  return 0;
+}
diff --git a/Tests/InterfaceBuildTargets/testlib.cxx b/Tests/InterfaceBuildTargets/testlib.cxx
new file mode 100644
index 0000000..02bd6b0
--- /dev/null
+++ b/Tests/InterfaceBuildTargets/testlib.cxx
@@ -0,0 +1,5 @@
+
+void testlib(void)
+{
+
+}