Merge topic 'ios-rpath-linker-flag' into release-3.20

4aed96e2 Apple: Set CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG on non-macOS too

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5980

Help/prop_tgt/INSTALL_NAME_DIR.rst

 INSTALL_NAME_DIR
 ----------------
 
-macOS directory name for installed targets.
+Directory name for installed targets on Apple platforms.
 
 ``INSTALL_NAME_DIR`` is a string specifying the directory portion of the
-"install_name" field of shared libraries on macOS to use in the
-installed targets.
+"install_name" field of shared libraries on Apple platforms for
+installed targets.  When not set, the default directory used is determined
+by :prop_tgt:`MACOSX_RPATH`.  Policies :policy:`CMP0068` and :policy:`CMP0042`
+are also relevant.
 
 This property is initialized by the value of the variable
 :variable:`CMAKE_INSTALL_NAME_DIR` if it is set when a target is

Help/release/3.20.rst

@@ -341,3 +341,9 @@ Changes made since CMake 3.20.0 include the following.
   and ``Intl_IS_BUILTIN``, but they were not implemented correctly.
   These have been removed and replaced with a single ``Intl_IS_BUILT_IN``
   check, whose name is consistent with the :module:`FindIconv` module.
+
+* The ``-rpath`` linker flag is now specified as supported on all Apple
+  platforms, not just macOS.  The ``install_name_dir`` used for
+  iOS, tvOS and watchOS should now default to ``@rpath`` instead of using
+  a full absolute path and failing at runtime when the library or framework
+  is embedded in an application bundle (see :prop_tgt:`XCODE_EMBED_<type>`).

Help/variable/CMAKE_INSTALL_NAME_DIR.rst

 CMAKE_INSTALL_NAME_DIR
 ----------------------
 
-macOS directory name for installed targets.
+Directory name for installed targets on Apple platforms.
 
 ``CMAKE_INSTALL_NAME_DIR`` is used to initialize the
 :prop_tgt:`INSTALL_NAME_DIR` property on all targets.  See that target

Modules/Platform/Darwin.cmake

@@ -47,11 +47,7 @@ set(CMAKE_SHARED_MODULE_PREFIX "lib")
 set(CMAKE_SHARED_MODULE_SUFFIX ".so")
 set(CMAKE_MODULE_EXISTS 1)
 set(CMAKE_DL_LIBS "")
-
-# Enable rpath support for 10.5 and greater where it is known to work.
-if("${DARWIN_MAJOR_VERSION}" GREATER 8)
-  set(CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG "-Wl,-rpath,")
-endif()
+set(CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG "-Wl,-rpath,")
 
 foreach(lang C CXX OBJC OBJCXX)
   set(CMAKE_${lang}_OSX_COMPATIBILITY_VERSION_FLAG "-compatibility_version ")