UseSWIG: Use standard library name conventions for csharp language

Fixes: #21542

Help/manual/cmake-policies.7.rst

@@ -57,7 +57,8 @@ Policies Introduced by CMake 3.21
 .. toctree::
    :maxdepth: 1
 
-   CMP0121: The list command detects invalid indicies </policy/CMP0121>
+   CMP0122: UseSWIG use standard library name conventions for csharp language. </policy/CMP0122>
+   CMP0121: The list command detects invalid indicies. </policy/CMP0121>
 
 Policies Introduced by CMake 3.20
 =================================

Help/policy/CMP0122.rst

@@ -0,0 +1,17 @@
+CMP0122
+-------
+
+.. versionadded:: 3.21
+
+:module:`UseSWIG` use library name conventions for ``CSharp`` language.
+
+Starting with CMake 3.21, :module:`UseSWIG` generates now a library using
+default naming conventions. This policy provides compatibility with projects
+that expect the legacy behavior.
+
+This policy was introduced in CMake version 3.21.  CMake version
+|release| warns when the policy is not set and uses ``OLD`` behavior.
+Use the :command:`cmake_policy` command to set it to ``OLD`` or ``NEW``
+explicitly.
+
+.. include:: DEPRECATED.txt

Help/release/dev/UseSWIG-csharp.rst

@@ -0,0 +1,5 @@
+UseSWIG-csharp
+--------------
+
+* The :module:`UseSWIG` module use now standard library name conventions for
+  ``CSharp`` language. See policy :policy:`CMP0122`.

Modules/UseSWIG.cmake

@@ -38,7 +38,13 @@ Defines the following command for use with ``SWIG``:
 
   .. versionchanged:: 3.15
     Alternate library name (set with the :prop_tgt:`OUTPUT_NAME` property,
-    for example) will be passed on to Python and CSharp wrapper libraries.
+    for example) will be passed on to ``Python`` and ``CSharp`` wrapper
+    libraries.
+
+  .. versionchanged:: 3.21
+    Generated library use standard naming conventions for ``CSharp`` language
+    when policy :policy:`CMP0122` is set to ``NEW``. Otherwise, the legacy
+    behavior is applied.
 
   .. note::
 
@@ -950,6 +956,17 @@ function(SWIG_ADD_LIBRARY name)
     endif ()
   elseif (swig_lowercase_language STREQUAL "fortran")
     # Do *not* override the target's library prefix
+  elseif (swig_lowercase_language STREQUAL "csharp")
+    cmake_policy(GET CMP0122 csharp_naming_policy)
+    if (csharp_naming_policy STREQUAL "NEW")
+      # Do *not* override the target's library prefix
+    else()
+      if (NOT csharp_naming_policy)
+        cmake_policy(GET_WARNING CMP0122 _cmp0122_warning)
+        message(AUTHOR_WARNING "${_cmp0122_warning}\n")
+      endif()
+      set_target_properties (${target_name} PROPERTIES PREFIX "")
+    endif()
   else()
     # assume empty prefix because we expect the module to be dynamically loaded
     set_target_properties (${target_name} PROPERTIES PREFIX "")

Source/cmPolicies.h

@@ -362,7 +362,11 @@ class cmMakefile;
          cmPolicies::WARN)                                                    \
   SELECT(POLICY, CMP0121,                                                     \
          "The list() command now validates parsing of index arguments.", 3,   \
-         21, 0, cmPolicies::WARN)
+         21, 0, cmPolicies::WARN)                                             \
+  SELECT(                                                                     \
+    POLICY, CMP0122,                                                          \
+    "UseSWIG use standard library name conventions for csharp language.", 3,  \
+    21, 0, cmPolicies::WARN)
 
 #define CM_SELECT_ID(F, A1, A2, A3, A4, A5, A6) F(A1)
 #define CM_FOR_EACH_POLICY_ID(POLICY)                                         \

Tests/RunCMake/UseSWIG/CMP0122-NEW-check.cmake

@@ -0,0 +1,10 @@
+
+cmake_policy(VERSION 3.1)
+
+file(STRINGS "${RunCMake_TEST_BINARY_DIR}/CMP0122-library-name.txt" prefixes)
+
+list(GET prefixes 0 std_prefix)
+list(GET prefixes 1 lib_prefix)
+if (NOT std_prefix STREQUAL lib_prefix)
+  string (APPEND RunCMake_TEST_FAILED "\nFound prefix: '${lib_prefix}', expected: '${std_prefix}'.")
+endif()

Tests/RunCMake/UseSWIG/CMP0122-NEW.cmake

@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0122 NEW)
+include(CMP0122-common.cmake)

Tests/RunCMake/UseSWIG/CMP0122-OLD-check.cmake

@@ -0,0 +1,10 @@
+
+cmake_policy(VERSION 3.1)
+
+file(STRINGS "${RunCMake_TEST_BINARY_DIR}/CMP0122-library-name.txt" prefixes)
+
+list(GET prefixes 1 lib_prefix)
+if (lib_prefix)
+  # prefix must be empty
+  string (APPEND RunCMake_TEST_FAILED "\nFound unexpected prefix: '${lib_prefix}'.")
+endif()

Tests/RunCMake/UseSWIG/CMP0122-OLD.cmake

@@ -0,0 +1,2 @@
+cmake_policy(SET CMP0122 OLD)
+include(CMP0122-common.cmake)

Tests/RunCMake/UseSWIG/CMP0122-WARN-stderr.txt

@@ -0,0 +1,10 @@
+CMake Warning \(dev\) at .*/Modules/UseSWIG.cmake:[0-9]+ \(message\):
+  Policy CMP0122 is not set: UseSWIG use standard library name conventions
+  for csharp language\.  Run "cmake --help-policy CMP0122" for policy details\.
+  Use the cmake_policy command to set the policy and suppress this warning\.
+
+Call Stack \(most recent call first\):
+  CMP0122-common.cmake:9 \(swig_add_library\)
+  CMP0122-WARN.cmake:1 \(include\)
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers\.  Use -Wno-dev to suppress it\.$

Tests/RunCMake/UseSWIG/CMP0122-WARN.cmake

@@ -0,0 +1 @@
+include(CMP0122-common.cmake)

Tests/RunCMake/UseSWIG/CMP0122-common.cmake

@@ -0,0 +1,12 @@
+
+cmake_policy(SET CMP0078 NEW)
+cmake_policy(SET CMP0086 NEW)
+
+set(SWIG_EXECUTABLE "swig")
+set(SWIG_DIR "/swig")
+include(UseSWIG)
+
+swig_add_library(example LANGUAGE csharp TYPE SHARED SOURCES example.i)
+
+file(GENERATE OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/CMP0122-library-name.txt"
+     CONTENT "${CMAKE_SHARED_LIBRARY_PREFIX}\n$<TARGET_FILE_PREFIX:example>\n")

Tests/RunCMake/UseSWIG/RunCMakeTest.cmake

@@ -23,3 +23,7 @@ if (CMake_TEST_FindPython)
   run_cmake_target(CMP0086-NEW build example)
 
 endif()
+
+run_cmake(CMP0122-WARN)
+run_cmake(CMP0122-OLD)
+run_cmake(CMP0122-NEW)