CMake Use python instead of python3 when in a (non-base) conda environment

CMakeLists.txt

@@ -13,15 +13,6 @@
 # cloning or pulling the upstream repo. Once this is done, you don't need to do
 # it again until you pull from the upstream repo again.
 #
-# NOTE: If your `buck2` binary is not on the PATH, you can change this line to
-# say something like `-DBUCK2=/tmp/buck2` to point directly to the tool.
-#[[
-  (rm -rf cmake-out \
-    && mkdir cmake-out \
-    && cd cmake-out \
-    && cmake -DBUCK2=buck2 ..)
-]]
-#
 # ### Build ###
 #
 # NOTE: The `-j` argument specifies how many jobs/processes to use when
@@ -169,8 +160,9 @@ option(EXECUTORCH_BUILD_XNNPACK "Build the XNNPACK backend" OFF)
 option(EXECUTORCH_BUILD_VULKAN "Build the Vulkan backend" OFF)
 
 if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
+  resolve_python_executable()
 endif()
+message(STATUS "Using python executable '${PYTHON_EXECUTABLE}'")
 
 # TODO(dbort): Fix these warnings and remove this flag.
 set(_common_compile_options -Wno-deprecated-declarations -fPIC)

backends/apple/mps/CMakeLists.txt

@@ -11,15 +11,17 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 if(NOT FLATC_EXECUTABLE)
   set(FLATC_EXECUTABLE flatc)
 endif()

backends/vulkan/CMakeLists.txt

@@ -20,12 +20,14 @@ if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
 if(NOT RUNTIME_PATH)
   set(RUNTIME_PATH ${CMAKE_CURRENT_SOURCE_DIR}/runtime)
 endif()
 
 if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
+  resolve_python_executable()
 endif()
 
 if(NOT FLATC_EXECUTABLE)

backends/xnnpack/CMakeLists.txt

@@ -17,10 +17,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 if(NOT FLATC_EXECUTABLE)
   set(FLATC_EXECUTABLE flatc)
 endif()
@@ -32,6 +28,10 @@ endif()
 
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 set(_common_compile_options -Wno-deprecated-declarations)
 

build/Utils.cmake

@@ -203,3 +203,18 @@ function(resolve_buck2)
       endif()
     endif()
 endfunction()
+
+# Sets the value of the PYTHON_EXECUTABLE variable to 'python' if in
+# an active (non-base) conda environment, and 'python3' otherwise. This
+# maintains backwards compatibility for non-conda users and avoids conda
+# users needing to explicitly set PYTHON_EXECUTABLE=python.
+function(resolve_python_executable)
+  # Counter-intuitively, CONDA_DEFAULT_ENV contains the name of the
+  # active environment.
+  if(DEFINED ENV{CONDA_DEFAULT_ENV} AND 
+     NOT $ENV{CONDA_DEFAULT_ENV} STREQUAL "base")
+    set(PYTHON_EXECUTABLE python PARENT_SCOPE)
+  else()
+    set(PYTHON_EXECUTABLE python3 PARENT_SCOPE)
+  endif()
+endfunction()

configurations/CMakeLists.txt

@@ -11,9 +11,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/..)
@@ -23,6 +20,12 @@ if(NOT TORCH_ROOT)
   set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 set(_common_compile_options -Wno-deprecated-declarations)
 
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)

examples/apple/mps/CMakeLists.txt

@@ -18,10 +18,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 if(NOT FLATC_EXECUTABLE)
   set(FLATC_EXECUTABLE flatc)
 endif()
@@ -31,6 +27,12 @@ if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 # Source root directory for pytorch.
 if(NOT TORCH_ROOT)
   set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)

examples/arm/CMakeLists.txt

@@ -16,14 +16,17 @@ project(arm_example)
 option(EXECUTORCH_SELECT_OPS_LIST "Register the following list of ops" OFF)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 endif()
+
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 # Source root directory for pytorch.
 if(NOT TORCH_ROOT)
   set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)

examples/models/llama2/CMakeLists.txt

@@ -20,13 +20,15 @@ project(llama_runner)
 
 option(EXECUTORCH_BUILD_OPTIMIZED "Build the optimized kernels" OFF)
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
   # Can't set to 11 due to executor_runner.cpp make_unique

examples/portable/custom_ops/CMakeLists.txt

@@ -22,9 +22,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
@@ -37,6 +34,10 @@ endif()
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 
 # Let files say "include <executorch/path/to/header.h>".

examples/qualcomm/CMakeLists.txt

@@ -11,9 +11,6 @@ endif()
 cmake_minimum_required(VERSION 3.19)
 project(qualcomm_runner_example)
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
@@ -23,6 +20,13 @@ if(NOT TORCH_ROOT)
   set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE Debug)
 endif()
@@ -41,7 +45,6 @@ set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 #
 # The `_<target>_srcs` lists are defined by including ${EXECUTORCH_SRCS_FILE}.
 #
-include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 set(EXECUTORCH_SRCS_FILE
   "${CMAKE_CURRENT_BINARY_DIR}/../../executorch_srcs.cmake"
 )
@@ -55,7 +58,6 @@ get_filename_component(EXECUTORCH_SOURCE_DIR
 set(_qnn_executor_runner__srcs ${_executor_runner__srcs})
 
 # portable_ops_lib
-include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 gen_selected_ops("" "" "ON")
 generate_bindings_for_kernels(
   FUNCTIONS_YAML ${EXECUTORCH_ROOT}/kernels/portable/functions.yaml

examples/sdk/CMakeLists.txt

@@ -14,9 +14,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
@@ -29,6 +26,10 @@ endif()
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 
 # Let files say "include <executorch/path/to/header.h>".

examples/selective_build/CMakeLists.txt

@@ -18,15 +18,16 @@
 cmake_minimum_required(VERSION 3.19)
 project(selective_build_example)
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
+
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
   # Can't set to 11 due to executor_runner.cpp make_unique

examples/xtensa/CMakeLists.txt

@@ -11,10 +11,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 # Set the project name.
 project(xtensa_executorch_example)
 
@@ -23,6 +19,12 @@ if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 endif()
 
+include(${EXECUTORCH_ROOT}/build/Utils.cmake)
+
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 # Let files say "include <executorch/path/to/header.h>".
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 

examples/xtensa/ops/CMakeLists.txt

@@ -11,10 +11,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
-
 # Source root directory for pytorch.
 if(NOT TORCH_ROOT)
   set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
@@ -23,6 +19,10 @@ endif()
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 # ATen compliant ops that are needed to run this model.
 set(_aten_ops__srcs
     "${CMAKE_CURRENT_SOURCE_DIR}/op_add.cpp"

install_requirements.sh

@@ -7,14 +7,14 @@
 
 # Install required python dependencies for developing
 # Dependencies are defined in .pyproject.toml
-if [[ -z $BUCK ]];
-then
-  BUCK=buck2
-fi
-
 if [[ -z $PYTHON_EXECUTABLE ]];
 then
-  PYTHON_EXECUTABLE=python3
+  if [[ -z $CONDA_DEFAULT_ENV ]] || [[ $CONDA_DEFAULT_ENV == "base" ]];
+  then
+    PYTHON_EXECUTABLE=python3
+  else
+    PYTHON_EXECUTABLE=python
+  fi
 fi
 
 # Parse options.

kernels/optimized/CMakeLists.txt

@@ -16,9 +16,6 @@ if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
 endif()
 
-if(NOT PYTHON_EXECUTABLE)
-  set(PYTHON_EXECUTABLE python3)
-endif()
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
@@ -33,6 +30,10 @@ set(_common_compile_options -Wno-deprecated-declarations)
 include(${EXECUTORCH_ROOT}/build/Utils.cmake)
 include(${EXECUTORCH_ROOT}/build/Codegen.cmake)
 
+if(NOT PYTHON_EXECUTABLE)
+  resolve_python_executable()
+endif()
+
 # Generate C++ bindings to register kernels into both PyTorch (for AOT) and
 # Executorch (for runtime). Here select all ops in optimized.yaml
 set(_yaml "${CMAKE_CURRENT_LIST_DIR}/optimized-oss.yaml")