Merge topic 'build-interface-targets'

bafa9fe887 fileapi: Add INTERFACE libraries with SOURCES to codemodel-v2
4391913133 Add INTERFACE libraries to generated buildsystem if they have SOURCES
afb998704e Remove filtering of allowed INTERFACE library properties
e7edba2baf Makefiles: Use IsInBuildSystem in global generator target type checks

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5078

2 files changed, 23 insertions, 22 deletions

diff --git a/Help/manual/cmake-buildsystem.7.rst b/Help/manual/cmake-buildsystem.7.rst
index d8142a2..cd27316 100644
--- a/Help/manual/cmake-buildsystem.7.rst
+++ b/Help/manual/cmake-buildsystem.7.rst
@@ -922,8 +922,8 @@ property from it:
 Interface Libraries
 -------------------
 
-An ``INTERFACE`` target has no :prop_tgt:`LOCATION` and is mutable, but is
-otherwise similar to an :prop_tgt:`IMPORTED` target.
+An ``INTERFACE`` library target does not compile sources and does not
+produce a library artifact on disk, so it has no :prop_tgt:`LOCATION`.
 
 It may specify usage requirements such as
 :prop_tgt:`INTERFACE_INCLUDE_DIRECTORIES`,
@@ -937,11 +937,22 @@ Only the ``INTERFACE`` modes of the :command:`target_include_directories`,
 :command:`target_sources`, and :command:`target_link_libraries` commands
 may be used with ``INTERFACE`` libraries.
 
+Since CMake 3.19, an ``INTERFACE`` library target may optionally contain
+source files.  An interface library that contains source files will be
+included as a build target in the generated buildsystem.  It does not
+compile sources, but may contain custom commands to generate other sources.
+Additionally, IDEs will show the source files as part of the target for
+interactive reading and editing.
+
 A primary use-case for ``INTERFACE`` libraries is header-only libraries.
 
 .. code-block:: cmake
 
-  add_library(Eigen INTERFACE)
+  add_library(Eigen INTERFACE
+    src/eigen.h
+    src/vector.h
+    src/matrix.h
+    )
   target_include_directories(Eigen INTERFACE
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
     $<INSTALL_INTERFACE:include/Eigen>
@@ -975,25 +986,17 @@ This way, the build specification of ``exe1`` is expressed entirely as linked
 targets, and the complexity of compiler-specific flags is encapsulated in an
 ``INTERFACE`` library target.
 
-The properties permitted to be set on or read from an ``INTERFACE`` library
-are:
-
-* Properties matching ``INTERFACE_*``
-* Built-in properties matching ``COMPATIBLE_INTERFACE_*``
-* ``EXPORT_NAME``
-* ``EXPORT_PROPERTIES``
-* ``IMPORTED``
-* ``MANUALLY_ADDED_DEPENDENCIES``
-* ``NAME``
-* Properties matching ``IMPORTED_LIBNAME_*``
-* Properties matching ``MAP_IMPORTED_CONFIG_*``
-
 ``INTERFACE`` libraries may be installed and exported.  Any content they refer
 to must be installed separately:
 
 .. code-block:: cmake
 
-  add_library(Eigen INTERFACE)
+  set(Eigen_headers
+    src/eigen.h
+    src/vector.h
+    src/matrix.h
+    )
+  add_library(Eigen INTERFACE ${Eigen_headers})
   target_include_directories(Eigen INTERFACE
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
     $<INSTALL_INTERFACE:include/Eigen>
@@ -1003,9 +1006,6 @@ to must be installed separately:
   install(EXPORT eigenExport NAMESPACE Upstream::
     DESTINATION lib/cmake/Eigen
   )
-  install(FILES
-      ${CMAKE_CURRENT_SOURCE_DIR}/src/eigen.h
-      ${CMAKE_CURRENT_SOURCE_DIR}/src/vector.h
-      ${CMAKE_CURRENT_SOURCE_DIR}/src/matrix.h
+  install(FILES ${Eigen_headers}
     DESTINATION include/Eigen
   )
diff --git a/Help/manual/cmake-file-api.7.rst b/Help/manual/cmake-file-api.7.rst
index 34edc56..6876e1c 100644
--- a/Help/manual/cmake-file-api.7.rst
+++ b/Help/manual/cmake-file-api.7.rst
@@ -650,7 +650,8 @@ with members:
 ``type``
   A string specifying the type of the target.  The value is one of
   ``EXECUTABLE``, ``STATIC_LIBRARY``, ``SHARED_LIBRARY``,
-  ``MODULE_LIBRARY``, ``OBJECT_LIBRARY``, or ``UTILITY``.
+  ``MODULE_LIBRARY``, ``OBJECT_LIBRARY``, ``INTERFACE_LIBRARY``,
+  or ``UTILITY``.
 
 ``backtrace``
   Optional member that is present when a CMake language backtrace to