[vcpkg-get-python] Add INTERPRETER keyword (#43732)

ports/vcpkg-get-python/vcpkg-port-config.cmake

@@ -1,6 +1,10 @@
 include_guard(GLOBAL)
 
 function(vcpkg_get_vcpkg_installed_python out_python)
+  cmake_parse_arguments(PARSE_ARGV 1 "arg" "INTERPRETER" "" "")
+  if(DEFINED arg_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR "${CMAKE_CURRENT_FUNCTION} was passed extra arguments: ${arg_UNPARSED_ARGUMENTS}")
+  endif()
   if(NOT VCPKG_TARGET_IS_WINDOWS)
     # vcpkg installed python on !windows works as normal python would work.
     set(${out_python} "${CURRENT_HOST_INSTALLED_DIR}/tools/python3/python3" PARENT_SCOPE)
@@ -9,6 +13,9 @@ function(vcpkg_get_vcpkg_installed_python out_python)
   if(DEFINED CACHE{z_vcpkg_get_vcpkg_installed_python})
     set(${out_python} "${z_vcpkg_get_vcpkg_installed_python}" PARENT_SCOPE)
     return()
+  elseif(arg_INTERPRETER AND DEFINED CACHE{z_vcpkg_get_vcpkg_installed_python_interpreter})
+    set(${out_python} "${z_vcpkg_get_vcpkg_installed_python_interpreter}" PARENT_SCOPE)
+    return()
   endif()
 
   # On windows python is unable to lookup DLLs, so a manual venv is created
@@ -48,10 +55,26 @@ if vcpkg_bin_path.is_dir():
 "
 )
 
- file(COPY "${CURRENT_INSTALLED_DIR}/${PYTHON3_INCLUDE}/" DESTINATION "${python_base}/include")
- set(suffix "PCBuild/AMD64") # TODO: ask python for the correct suffix.
- file(COPY "${CURRENT_INSTALLED_DIR}/lib/python${PYTHON3_VERSION_MAJOR}${PYTHON3_VERSION_MINOR}.lib" DESTINATION "${python_base}/${suffix}")
+  # This part is intentionally copies headers and link libraries from the target
+  # installation (CURRENT_INSTALLED_DIR): The function provides infrastructure for
+  # building extensions for the target python while running the host python interpreter.
+  # The calling port is responsible to provided the target python3 dependency.
+  # However, it is possible to use just the interpreter,
+  # e.g. for running extensions already installed in the host triplet.
+  if(EXISTS "${CURRENT_INSTALLED_DIR}/lib/python${PYTHON3_VERSION_MAJOR}${PYTHON3_VERSION_MINOR}.lib")
+    file(COPY "${CURRENT_INSTALLED_DIR}/${PYTHON3_INCLUDE}/" DESTINATION "${python_base}/include")
+    set(suffix "PCBuild/AMD64") # TODO: ask python for the correct suffix.
+    file(COPY "${CURRENT_INSTALLED_DIR}/lib/python${PYTHON3_VERSION_MAJOR}${PYTHON3_VERSION_MINOR}.lib" DESTINATION "${python_base}/${suffix}")
+    set(z_vcpkg_get_vcpkg_installed_python "${python_base}/Scripts/python.exe" CACHE INTERNAL "")
+  elseif(arg_INTERPRETER)
+    set(z_vcpkg_get_vcpkg_installed_python_interpreter "${python_base}/Scripts/python.exe" CACHE INTERNAL "")
+  else()
+    message(${Z_VCPKG_BACKCOMPAT_MESSAGE_LEVEL}
+      "Target python3 installation was not found, and the INTERPRETER wasn't given."
+      " Either add a \"python3\" dependency to ${PORT},"
+      " or add 'INTERPRETER' to the '${CMAKE_CURRENT_FUNCTION}' call."
+    )
+  endif()
 
- set(${out_python} "${python_base}/Scripts/python.exe" PARENT_SCOPE)
- set(z_vcpkg_get_vcpkg_installed_python "${python_base}/Scripts/python.exe" CACHE INTERNAL "")
+  set(${out_python} "${python_base}/Scripts/python.exe" PARENT_SCOPE)
 endfunction()

ports/vcpkg-get-python/vcpkg.json

@@ -1,6 +1,6 @@
 {
   "name": "vcpkg-get-python",
-  "version-date": "2024-06-22",
+  "version-date": "2025-02-09",
   "license": "MIT",
   "supports": "native"
 }

versions/baseline.json

@@ -9505,7 +9505,7 @@
       "port-version": 0
     },
     "vcpkg-get-python": {
-      "baseline": "2024-06-22",
+      "baseline": "2025-02-09",
       "port-version": 0
     },
     "vcpkg-get-python-packages": {

versions/v-/vcpkg-get-python.json

@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "0a0384810888b341ad84b0e08559481ff9a82150",
+      "version-date": "2025-02-09",
+      "port-version": 0
+    },
     {
       "git-tree": "e1993fbd0925b052b31f62967690a2634cb952a2",
       "version-date": "2024-06-22",