UseSWIG: add policy to manage target naming strategy.

1 files changed, 26 insertions, 15 deletions

diff --git a/Modules/UseSWIG.cmake b/Modules/UseSWIG.cmake
index 7460932885..e7aaf32eef 100644
--- a/Modules/UseSWIG.cmake
+++ b/Modules/UseSWIG.cmake
@@ -30,9 +30,10 @@ Defines the following command for use with ``SWIG``:
 
   .. note::
 
-    The variable ``SWIG_MODULE_<name>_REAL_NAME`` will be set to the name
-    of the swig module target library. This variable is useless if variable
-    ``UseSWIG_TARGET_NAME_PREFERENCE`` is set to ``STANDARD``.
+    This command creates a target with the specified ``<name>`` when
+    policy :policy:`CMP0078` is set to ``NEW``.  Otherwise, the legacy
+    behavior will choose a different target name and store it in the
+    ``SWIG_MODULE_<name>_REAL_NAME`` variable.
 
   .. note::
 
@@ -197,13 +198,6 @@ information about support files generated by ``SWIG`` interface compilation.
 Some variables can be set to customize the behavior of ``swig_add_library``
 as well as ``SWIG``:
 
-``UseSWIG_TARGET_NAME_PREFERENCE``
-  Specify target name strategy.
-
-  * Set to ``LEGACY`` or undefined: legacy strategy is applied. Variable
-    ``SWIG_MODULE_<name>_REAL_NAME`` must be used to get real target name.
-  * Set to ``STANDARD``: target name matches specified name.
-
 ``UseSWIG_MODULE_VERSION``
   Specify different behaviors for ``UseSWIG`` module.
 
@@ -225,8 +219,13 @@ as well as ``SWIG``:
   Specify extra dependencies for the generated module for ``<name>``.
 #]=======================================================================]
 
-
+cmake_policy(GET CMP0078 target_name_policy)
 cmake_policy (VERSION 3.12)
+if (target_name_policy)
+  # respect user choice regarding CMP0078 policy
+  cmake_policy(SET CMP0078 ${target_name_policy})
+endif()
+unset(target_name_policy)
 
 set(SWIG_CXX_EXTENSION "cxx")
 set(SWIG_EXTRA_LIBRARIES "")
@@ -545,10 +544,22 @@ function(SWIG_ADD_LIBRARY name)
     unset(_SAM_TYPE)
   endif()
 
-  if (NOT DEFINED UseSWIG_TARGET_NAME_PREFERENCE)
-    set (UseSWIG_TARGET_NAME_PREFERENCE LEGACY)
-  elseif (NOT UseSWIG_TARGET_NAME_PREFERENCE MATCHES "^(LEGACY|STANDARD)$")
-    message (FATAL_ERROR "UseSWIG_TARGET_NAME_PREFERENCE: ${UseSWIG_TARGET_NAME_PREFERENCE}: invalid value. 'LEGACY' or 'STANDARD' is expected.")
+  cmake_policy(GET CMP0078 target_name_policy)
+  if (target_name_policy STREQUAL "NEW")
+    set (UseSWIG_TARGET_NAME_PREFERENCE STANDARD)
+  else()
+    if (NOT target_name_policy)
+      message(AUTHOR_WARNING
+        "Policy CMP0078 is not set.  "
+        "Run \"cmake --help-policy CMP0078\" for policy details.  "
+        "Use the cmake_policy command to set the policy and suppress this warning."
+        )
+    endif()
+    if (NOT DEFINED UseSWIG_TARGET_NAME_PREFERENCE)
+      set (UseSWIG_TARGET_NAME_PREFERENCE LEGACY)
+    elseif (NOT UseSWIG_TARGET_NAME_PREFERENCE MATCHES "^(LEGACY|STANDARD)$")
+      message (FATAL_ERROR "UseSWIG_TARGET_NAME_PREFERENCE: ${UseSWIG_TARGET_NAME_PREFERENCE}: invalid value. 'LEGACY' or 'STANDARD' is expected.")
+    endif()
   endif()
 
   if (NOT DEFINED UseSWIG_MODULE_VERSION)