Merge topic 'FindSWIG-components'

e131d9f974 FindSWIG: Add COMPONENTS support for SWIG target languages

Acked-by: Kitware Robot <[email protected]>
Merge-request: !4384

Help/release/dev/findswig-components.rst

@@ -0,0 +1,5 @@
+findswig-components
+-------------------
+
+* The :module:`FindSWIG` module now accepts target languages as  ``COMPONENTS``
+  and ``OPTIONAL_COMPONENTS`` arguments to ``find_package``.

Modules/FindSWIG.cmake

@@ -5,25 +5,49 @@
 FindSWIG
 --------
 
-Find Simplified Wrapper and Interface Generator (SWIG)
+Find the Simplified Wrapper and Interface Generator (SWIG_) executable.
 
-This module finds an installed SWIG.  It sets the following variables:
-
-::
-
-  SWIG_FOUND - set to "True" if SWIG is found
-  SWIG_DIR - the directory where swig is installed
-  SWIG_EXECUTABLE - the path to the swig executable
-  SWIG_VERSION   - the version number of the swig executable
 
+This module finds an installed SWIG and determines its version. If a
+``COMPONENTS`` or ``OPTIONAL_COMPONENTS`` argument is given to ``find_package``,
+it will also determine supported target languages.  The module sents the
+following variables:
 
+``SWIG_FOUND``
+  Whether SWIG and any required components were found on the system.
+``SWIG_EXECUTABLE``
+  Path to the SWIG executable.
+``SWIG_DIR``
+  Path to the installed SWIG ``Lib`` directory (result of ``swig -swiglib``).
+``SWIG_VERSION``
+  SWIG executable version (result of ``swig -version``).
+``SWIG_<lang>_FOUND``
+  If ``COMPONENTS`` or ``OPTIONAL_COMPONENTS`` are requested, each available
+  target language ``<lang>`` (lowercase) will be set to TRUE.
 
-The minimum required version of SWIG can be specified using the
-standard syntax, e.g.   :command:`find_package(SWIG 1.1)`
+Any ``COMPONENTS`` given to ``find_package`` should be the names of supported
+target languages as provided to the LANGUAGE argument of ``swig_add_library``,
+such as ``python`` or ``perl5``. Language names *must* be lowercase.
 
 All information is collected from the ``SWIG_EXECUTABLE``, so the version
 to be found can be changed from the command line by means of setting
-``SWIG_EXECUTABLE``
+``SWIG_EXECUTABLE``.
+
+Example usage requiring SWIG 4.0 or higher and Python language support, with
+optional Fortran support:
+
+.. code-block:: cmake
+
+   find_package(SWIG 4.0 COMPONENTS python OPTIONAL_COMPONENTS fortran)
+   if(SWIG_FOUND)
+     message("SWIG found: ${SWIG_EXECUTABLE}")
+     if(NOT SWIG_fortran_FOUND)
+       message(WARNING "SWIG Fortran bindings cannot be generated")
+     endif()
+   endif()
+
+.. _`SWIG`: http://swig.org
+
 #]=======================================================================]
 
 find_program(SWIG_EXECUTABLE NAMES swig4.0 swig3.0 swig2.0 swig)
@@ -58,10 +82,29 @@ if(SWIG_EXECUTABLE)
       endif()
     endif()
   endif()
+
+  if(SWIG_FIND_COMPONENTS)
+    execute_process(COMMAND ${SWIG_EXECUTABLE} -help
+      OUTPUT_VARIABLE SWIG_swighelp_output
+      ERROR_VARIABLE SWIG_swighelp_error
+      RESULT_VARIABLE SWIG_swighelp_result)
+    if(SWIG_swighelp_result)
+      message(SEND_ERROR "Command \"${SWIG_EXECUTABLE} -help\" failed with output:\n${SWIG_swiglib_error}")
+    else()
+      string(REPLACE "\n" ";" SWIG_swighelp_output "${SWIG_swighelp_output}")
+      foreach(SWIG_line IN LISTS SWIG_swighelp_output)
+        if(SWIG_line MATCHES "-([A-Za-z0-9_]+) +- *Generate.*wrappers")
+          set(SWIG_${CMAKE_MATCH_1}_FOUND TRUE)
+        endif()
+      endforeach()
+    endif()
+  endif()
 endif()
 
 include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(SWIG  REQUIRED_VARS SWIG_EXECUTABLE SWIG_DIR
-                                        VERSION_VAR SWIG_VERSION )
+find_package_handle_standard_args(
+  SWIG HANDLE_COMPONENTS
+  REQUIRED_VARS SWIG_EXECUTABLE SWIG_DIR
+  VERSION_VAR SWIG_VERSION)
 
 mark_as_advanced(SWIG_DIR SWIG_VERSION SWIG_EXECUTABLE)

Tests/RunCMake/CMakeLists.txt

@@ -188,6 +188,7 @@ add_RunCMake_test(FindBoost)
 add_RunCMake_test(FindLua)
 add_RunCMake_test(FindOpenGL)
 if(CMake_TEST_UseSWIG)
+  add_RunCMake_test(FindSWIG)
   add_RunCMake_test(UseSWIG -DCMake_TEST_FindPython=${CMake_TEST_FindPython})
 endif()
 if(NOT CMAKE_C_COMPILER_ID MATCHES "Watcom")

Tests/RunCMake/FindSWIG/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.10)
+project(${RunCMake_TEST} C)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/FindSWIG/RunCMakeTest.cmake

@@ -0,0 +1,4 @@
+include(RunCMake)
+
+run_cmake(components)
+run_cmake(missing-components)

Tests/RunCMake/FindSWIG/components-stdout.txt

@@ -0,0 +1,6 @@
+-- Found SWIG: [^ ]+ \(found version "[0-9.]+"\) found components: java python missing components: PERL
+-- SWIG_VERSION='[0-9.]+'
+-- SWIG_java_FOUND=TRUE
+-- SWIG_python_FOUND=TRUE
+-- SWIG_PERL_FOUND=
+-- Configuring done

Tests/RunCMake/FindSWIG/components.cmake

@@ -0,0 +1,9 @@
+# Note that 'perl' will not be found because it is not lowercase.
+find_package(SWIG REQUIRED
+  COMPONENTS java
+  OPTIONAL_COMPONENTS python PERL)
+
+message(STATUS "SWIG_VERSION='${SWIG_VERSION}'")
+foreach(_lang java python PERL)
+  message(STATUS "SWIG_${_lang}_FOUND=${SWIG_${_lang}_FOUND}")
+endforeach()

Tests/RunCMake/FindSWIG/missing-components-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/FindSWIG/missing-components-stderr.txt

@@ -0,0 +1 @@
+Could NOT find SWIG \(missing: invalid\)

Tests/RunCMake/FindSWIG/missing-components.cmake

@@ -0,0 +1,3 @@
+find_package(SWIG REQUIRED
+  COMPONENTS invalid
+  OPTIONAL_COMPONENTS alsoinvalid)