FindPython: Add support for python specific crosscompiling emulator

Fixes: #27996

Help/release/dev/FindPython-CROSSCOMPILING_EMULATOR.rst

@@ -0,0 +1,8 @@
+FindPython-CROSSCOMPILING_EMULATOR
+----------------------------------
+
+* The :module:`FindPython`, :module:`FindPython2`, and :module:`FindPython3`
+  modules gained the possibility to override the
+  :variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable by respectively, the
+  variables ``Python_CROSSCOMPILING_EMULATOR``,
+  ``Python2_CROSSCOMPILING_EMULATOR``, and ``Python3_CROSSCOMPILING_EMULATOR``.

Modules/FindPython.cmake

@@ -652,6 +652,19 @@ can be controlled with the following variable:
     ``_FOUND`` variables (i.e. without the custom prefix) are also defined by
     each call to the :command:`find_package` command.
 
+``Python_CROSSCOMPILING_EMULATOR``
+  .. versionadded:: 4.5
+
+  This variable is only used when the :variable:`CMAKE_CROSSCOMPILING` variable
+  is on and the policy :policy:`CMP0190` is ``NEW``. It should point to a
+  command on the host system that can run executable built for the target
+  system. This variable takes precedence over the
+  :variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable.
+
+  Moreover, to support some specific cases (like
+  `crossenv <https://github.com/robotpy/crossenv>`_), it is possible to set an
+  empty string to this variable.
+
 Commands
 ^^^^^^^^
 

Modules/FindPython/Support.cmake

@@ -1034,7 +1034,7 @@ function (_PYTHON_GET_LAUNCHER _PYTHON_PGL_NAME)
   endif()
 
   if (_${_PYTHON_PREFIX}_CROSSCOMPILING)
-    set (${_PYTHON_PGL_NAME} "${CMAKE_CROSSCOMPILING_EMULATOR}" PARENT_SCOPE)
+    set (${_PYTHON_PGL_NAME} "${_${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR}" PARENT_SCOPE)
     return()
   endif()
 
@@ -1642,16 +1642,23 @@ endif()
 
 ## handle cross-compiling constraints for components:
 ##  If Interpreter and/or Compiler are specified with Development components
-##  the CMAKE_CROSSCOMPILING_EMULATOR variable should be defined
+##  the Python_CROSSCOMPILING_EMULATOR or CMAKE_CROSSCOMPILING_EMULATOR variable
+##  should be defined
 cmake_policy (GET CMP0190 _${_PYTHON_PREFIX}_CROSSCOMPILING_POLICY)
 unset (_${_PYTHON_PREFIX}_CROSSCOMPILING)
+unset (_${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR)
 if (CMAKE_CROSSCOMPILING AND _${_PYTHON_PREFIX}_CROSSCOMPILING_POLICY STREQUAL "NEW")
   if (${_PYTHON_BASE}_FIND_COMPONENTS MATCHES "Interpreter|Compiler"
       AND ${_PYTHON_BASE}_FIND_COMPONENTS MATCHES "Development")
-    if (CMAKE_CROSSCOMPILING_EMULATOR)
+    if (DEFINED ${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR OR CMAKE_CROSSCOMPILING_EMULATOR)
       set (_${_PYTHON_PREFIX}_CROSSCOMPILING TRUE)
+      if (DEFINED ${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR)
+        set (_${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR "${${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR}")
+      else()
+        set (_${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR "${CMAKE_CROSSCOMPILING_EMULATOR}")
+      endif()
     else()
-      _python_display_failure ("${_PYTHON_PREFIX}: When cross-compiling, Interpreter and/or Compiler components cannot be searched when CMAKE_CROSSCOMPILING_EMULATOR variable is not specified (see policy CMP0190)." FATAL)
+      _python_display_failure ("${_PYTHON_PREFIX}: When cross-compiling, Interpreter and/or Compiler components cannot be searched when ${_PYTHON_PREFIX}_CROSSCOMPILING_EMULATOR or CMAKE_CROSSCOMPILING_EMULATOR variable is not specified (see policy CMP0190)." FATAL)
     endif()
   endif()
 endif()

Modules/FindPython2.cmake

@@ -497,6 +497,19 @@ can be controlled with the following variable:
     ``_FOUND`` variables (i.e. without the custom prefix) are also defined by
     each call to the :command:`find_package` command.
 
+``Python2_CROSSCOMPILING_EMULATOR``
+  .. versionadded:: 4.5
+
+  This variable is only used when the :variable:`CMAKE_CROSSCOMPILING` variable
+  is on and the policy :policy:`CMP0190` is ``NEW``. It should point to a
+  command on the host system that can run executable built for the target
+  system. This variable takes precedence over the
+  :variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable.
+
+  Moreover, to support some specific cases (like
+  `crossenv <https://github.com/robotpy/crossenv>`_), it is possible to set an
+  empty string to this variable.
+
 Commands
 ^^^^^^^^
 

Modules/FindPython3.cmake

@@ -651,6 +651,19 @@ can be controlled with the following variable:
     ``_FOUND`` variables (i.e. without the custom prefix) are also defined by
     each call to the :command:`find_package` command.
 
+``Python3_CROSSCOMPILING_EMULATOR``
+  .. versionadded:: 4.5
+
+  This variable is only used when the :variable:`CMAKE_CROSSCOMPILING` variable
+  is on and the policy :policy:`CMP0190` is ``NEW``. It should point to a
+  command on the host system that can run executable built for the target
+  system. This variable takes precedence over the
+  :variable:`CMAKE_CROSSCOMPILING_EMULATOR` variable.
+
+  Moreover, to support some specific cases (like
+  `crossenv <https://github.com/robotpy/crossenv>`_), it is possible to set an
+  empty string to this variable.
+
 Commands
 ^^^^^^^^
 

Tests/RunCMake/FindPython/CrossCompiling-BOTH.cmake

@@ -12,22 +12,25 @@ unset(${PYTHON}_ARTIFACTS_PREFIX)
 
 
 # Search cross-compilation artifacts
-## First, built an pseudo-emulator
-set(PSEUDO_EMULATOR_DIR "${CMAKE_CURRENT_BINARY_DIR}/pseudo_emulator")
 
-file(MAKE_DIRECTORY "${PSEUDO_EMULATOR_DIR}")
+if (NOT DEFINED ${PYTHON}_CROSSCOMPILING_EMULATOR)
+  ## First, built an pseudo-emulator
+  set(PSEUDO_EMULATOR_DIR "${CMAKE_CURRENT_BINARY_DIR}/pseudo_emulator")
 
-execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" -DCMAKE_BUILD_TYPE=Release
+  file(MAKE_DIRECTORY "${PSEUDO_EMULATOR_DIR}")
-                                           -S "${CMAKE_CURRENT_SOURCE_DIR}/pseudo_emulator"
-                                           -B "${PSEUDO_EMULATOR_DIR}"
-                COMMAND_ERROR_IS_FATAL ANY)
 
-execute_process(COMMAND "${CMAKE_COMMAND}" --build "${PSEUDO_EMULATOR_DIR}"
+  execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" -DCMAKE_BUILD_TYPE=Release
-                COMMAND_ERROR_IS_FATAL ANY)
+    -S "${CMAKE_CURRENT_SOURCE_DIR}/pseudo_emulator"
+    -B "${PSEUDO_EMULATOR_DIR}"
+    COMMAND_ERROR_IS_FATAL ANY)
+
+  execute_process(COMMAND "${CMAKE_COMMAND}" --build "${PSEUDO_EMULATOR_DIR}"
+    COMMAND_ERROR_IS_FATAL ANY)
+
+  ## Now, configure this pseudo-emulator
+  set(CMAKE_CROSSCOMPILING_EMULATOR "${PSEUDO_EMULATOR_DIR}/pseudo_emulator")
+endif()
 
-## Now, configure this pseudo-emulator
 set(CMAKE_CROSSCOMPILING TRUE)
-set(CMAKE_CROSSCOMPILING_EMULATOR "${PSEUDO_EMULATOR_DIR}/pseudo_emulator")
-
 
 find_package(${PYTHON} ${Python_REQUESTED_VERSION} REQUIRED COMPONENTS Interpreter Development)

Tests/RunCMake/FindPython/CrossCompiling-CMP0190-NEW.Python.V2-stderr.txt

@@ -1,4 +1,5 @@
 CMake Error at .+/Support\.cmake:[0-9]+ \(message\):
   Python: When cross-compiling, Interpreter and/or Compiler components cannot
-  be searched when CMAKE_CROSSCOMPILING_EMULATOR variable is not specified
+  be searched when Python_CROSSCOMPILING_EMULATOR or
-  \(see policy CMP0190\)\.
+  CMAKE_CROSSCOMPILING_EMULATOR variable is not specified \(see policy
+  CMP0190\)\.

Tests/RunCMake/FindPython/CrossCompiling-CMP0190-NEW.Python.V3-stderr.txt

@@ -1,4 +1,5 @@
 CMake Error at .+/Support\.cmake:[0-9]+ \(message\):
   Python: When cross-compiling, Interpreter and/or Compiler components cannot
-  be searched when CMAKE_CROSSCOMPILING_EMULATOR variable is not specified
+  be searched when Python_CROSSCOMPILING_EMULATOR or
-  \(see policy CMP0190\)\.
+  CMAKE_CROSSCOMPILING_EMULATOR variable is not specified \(see policy
+  CMP0190\)\.

Tests/RunCMake/FindPython/CrossCompiling-CMP0190-NEW.Python2-stderr.txt

@@ -1,4 +1,5 @@
 CMake Error at .+/Support\.cmake:[0-9]+ \(message\):
   Python2: When cross-compiling, Interpreter and/or Compiler components
-  cannot be searched when CMAKE_CROSSCOMPILING_EMULATOR variable is not
+  cannot be searched when Python2_CROSSCOMPILING_EMULATOR or
-  specified \(see policy CMP0190\)\.
+  CMAKE_CROSSCOMPILING_EMULATOR variable is not specified \(see policy
+  CMP0190\)\.

Tests/RunCMake/FindPython/CrossCompiling-CMP0190-NEW.Python3-stderr.txt

@@ -1,4 +1,5 @@
 CMake Error at .+/Support\.cmake:[0-9]+ \(message\):
   Python3: When cross-compiling, Interpreter and/or Compiler components
-  cannot be searched when CMAKE_CROSSCOMPILING_EMULATOR variable is not
+  cannot be searched when Python3_CROSSCOMPILING_EMULATOR or
-  specified \(see policy CMP0190\)\.
+  CMAKE_CROSSCOMPILING_EMULATOR variable is not specified \(see policy
+  CMP0190\)\.

Tests/RunCMake/FindPython/CrossCompiling-TARGET.cmake

@@ -2,22 +2,24 @@ cmake_policy(SET CMP0190 NEW)
 
 enable_language(C)
 
-## First, built an pseudo-emulator
+if (NOT DEFINED ${PYTHON}_CROSSCOMPILING_EMULATOR)
-set(PSEUDO_EMULATOR_DIR "${CMAKE_CURRENT_BINARY_DIR}/pseudo_emulator")
+  ## First, built an pseudo-emulator
+  set(PSEUDO_EMULATOR_DIR "${CMAKE_CURRENT_BINARY_DIR}/pseudo_emulator")
 
-file(MAKE_DIRECTORY "${PSEUDO_EMULATOR_DIR}")
+  file(MAKE_DIRECTORY "${PSEUDO_EMULATOR_DIR}")
 
-execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" -DCMAKE_BUILD_TYPE=Release
+  execute_process(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" -DCMAKE_BUILD_TYPE=Release
-                                           -S "${CMAKE_CURRENT_SOURCE_DIR}/pseudo_emulator"
+    -S "${CMAKE_CURRENT_SOURCE_DIR}/pseudo_emulator"
-                                           -B "${PSEUDO_EMULATOR_DIR}"
+    -B "${PSEUDO_EMULATOR_DIR}"
-                COMMAND_ERROR_IS_FATAL ANY)
+    COMMAND_ERROR_IS_FATAL ANY)
 
-execute_process(COMMAND "${CMAKE_COMMAND}" --build "${PSEUDO_EMULATOR_DIR}"
+  execute_process(COMMAND "${CMAKE_COMMAND}" --build "${PSEUDO_EMULATOR_DIR}"
-                COMMAND_ERROR_IS_FATAL ANY)
+    COMMAND_ERROR_IS_FATAL ANY)
+
+  ## Now, configure this pseudo-emulator
+  set(CMAKE_CROSSCOMPILING_EMULATOR "${PSEUDO_EMULATOR_DIR}/pseudo_emulator")
+endif()
 
-## Now, configure this pseudo-emulator
 set(CMAKE_CROSSCOMPILING TRUE)
-set(CMAKE_CROSSCOMPILING_EMULATOR "${PSEUDO_EMULATOR_DIR}/pseudo_emulator")
-
 
 find_package(${PYTHON} ${Python_REQUESTED_VERSION} REQUIRED COMPONENTS Interpreter Development)

Tests/RunCMake/FindPython/RunCMakeTest.cmake

@@ -167,11 +167,21 @@ if(CMake_TEST_FindPython2_CPython)
                                  OPTIONS -DPython_REQUESTED_VERSION=2)
   if(CMAKE_SYSTEM_NAME MATCHES "Linux|Darwin" AND NOT RunCMake_GENERATOR_IS_MULTI_CONFIG)
     run_python(CrossCompiling-TARGET TYPE Python2 VARIANT Python2)
+    run_python(CrossCompiling-TARGET TYPE Python2 VARIANT Python2.crossenv
+                                     OPTIONS "-DPython2_CROSSCOMPILING_EMULATOR=")
     run_python(CrossCompiling-TARGET TYPE Python VARIANT Python.V2
                                      OPTIONS -DPython_REQUESTED_VERSION=2)
+    run_python(CrossCompiling-TARGET TYPE Python VARIANT Python.V2.crossenv
+                                     OPTIONS -DPython_REQUESTED_VERSION=2
+                                             "-DPython_CROSSCOMPILING_EMULATOR=")
     run_python(CrossCompiling-BOTH TYPE Python2 VARIANT Python2)
+    run_python(CrossCompiling-BOTH TYPE Python2 VARIANT Python2.crossenv
+                                   OPTIONS "-DPython2_CROSSCOMPILING_EMULATOR=")
     run_python(CrossCompiling-BOTH TYPE Python VARIANT Python.V2
                                    OPTIONS -DPython_REQUESTED_VERSION=2)
+    run_python(CrossCompiling-BOTH TYPE Python VARIANT Python.V2.crossenv
+                                   OPTIONS -DPython_REQUESTED_VERSION=2
+                                           "-DPython_CROSSCOMPILING_EMULATOR=")
   endif()
 endif()
 
@@ -225,9 +235,19 @@ if(CMake_TEST_FindPython3_CPython)
     run_python(CrossCompiling-TARGET TYPE Python3 VARIANT Python3)
     run_python(CrossCompiling-TARGET TYPE Python VARIANT Python.V3
                                      OPTIONS -DPython_REQUESTED_VERSION=3)
+    run_python(CrossCompiling-TARGET TYPE Python3 VARIANT Python3.crossenv
+                                     OPTIONS "-DPython3_CROSSCOMPILING_EMULATOR=")
+    run_python(CrossCompiling-TARGET TYPE Python VARIANT Python.V3.crossenv
+                                     OPTIONS -DPython_REQUESTED_VERSION=3
+                                             "-DPython_CROSSCOMPILING_EMULATOR=")
     run_python(CrossCompiling-BOTH TYPE Python3 VARIANT Python3)
+    run_python(CrossCompiling-BOTH TYPE Python3 VARIANT Python3.crossenv
+                                   OPTIONS "-DPython3_CROSSCOMPILING_EMULATOR=")
     run_python(CrossCompiling-BOTH TYPE Python VARIANT Python.V3
                                         OPTIONS -DPython_REQUESTED_VERSION=3)
+    run_python(CrossCompiling-BOTH TYPE Python VARIANT Python.V3.crossenv
+                                        OPTIONS -DPython_REQUESTED_VERSION=3
+                                                "-DPython_CROSSCOMPILING_EMULATOR=")
   endif()
 endif()