From 7a2c126054fa6b58b68a89f5aa7a6b0e91be8de4 Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Wed, 31 Mar 2021 17:35:00 +1100
Subject: [PATCH 1/3] cmake: Fix passing PYTHON path via CMake variable if
 using IDF as library

Closes https://github.com/espressif/esp-idf/issues/6285
---
 tools/cmake/build.cmake   |  6 ++++--
 tools/cmake/project.cmake | 13 ++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/tools/cmake/build.cmake b/tools/cmake/build.cmake
index 52631a1005..a6202025b0 100644
--- a/tools/cmake/build.cmake
+++ b/tools/cmake/build.cmake
@@ -130,9 +130,11 @@ function(__build_init idf_path)
     # Must be global so as to be accessible from any subdirectory in custom projects.
     add_library(__idf_build_target STATIC IMPORTED GLOBAL)
 
-    set_default(python "python")
+    # Set the Python path (which may be passed in via -DPYTHON=) and store in a build property
+    set_default(PYTHON "python")
+    file(TO_CMAKE_PATH ${PYTHON} PYTHON)
+    idf_build_set_property(PYTHON ${PYTHON})
 
-    idf_build_set_property(PYTHON ${python})
     idf_build_set_property(IDF_PATH ${idf_path})
 
     idf_build_set_property(__PREFIX idf)
diff --git a/tools/cmake/project.cmake b/tools/cmake/project.cmake
index c9479565e5..fc0c4d87a2 100644
--- a/tools/cmake/project.cmake
+++ b/tools/cmake/project.cmake
@@ -6,12 +6,15 @@ cmake_minimum_required(VERSION 3.5)
 # call.
 include(${CMAKE_CURRENT_LIST_DIR}/idf.cmake)
 
+# legacy variable for compatibility
 set(IDFTOOL ${PYTHON} "${IDF_PATH}/tools/idf.py")
-# Internally, the Python interpreter is already set to 'python'. Re-set here
-# to be absolutely sure.
-set_default(PYTHON "python")
-file(TO_CMAKE_PATH ${PYTHON} PYTHON)
-idf_build_set_property(PYTHON ${PYTHON})
+
+# setting PYTHON variable here for compatibility only, new code should use
+# idf_build_get_property(variable PYTHON)
+idf_build_get_property(PYTHON PYTHON)
+if(NOT PYTHON)
+    message(FATAL_ERROR "Internal error, PYTHON build property not set correctly.")
+endif()
 
 # On processing, checking Python required modules can be turned off if it was
 # already checked externally.

From 886c4651207ce8afe115b41fba2bd72b55d1c6f0 Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Wed, 31 Mar 2021 17:35:42 +1100
Subject: [PATCH 2/3] cmake: Set IDFTOOL variable using the correct PYTHON
 interpreter variable

---
 tools/cmake/project.cmake | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/cmake/project.cmake b/tools/cmake/project.cmake
index fc0c4d87a2..139063b643 100644
--- a/tools/cmake/project.cmake
+++ b/tools/cmake/project.cmake
@@ -6,9 +6,6 @@ cmake_minimum_required(VERSION 3.5)
 # call.
 include(${CMAKE_CURRENT_LIST_DIR}/idf.cmake)
 
-# legacy variable for compatibility
-set(IDFTOOL ${PYTHON} "${IDF_PATH}/tools/idf.py")
-
 # setting PYTHON variable here for compatibility only, new code should use
 # idf_build_get_property(variable PYTHON)
 idf_build_get_property(PYTHON PYTHON)
@@ -16,6 +13,9 @@ if(NOT PYTHON)
     message(FATAL_ERROR "Internal error, PYTHON build property not set correctly.")
 endif()
 
+# legacy variable for compatibility
+set(IDFTOOL ${PYTHON} "${IDF_PATH}/tools/idf.py")
+
 # On processing, checking Python required modules can be turned off if it was
 # already checked externally.
 if(PYTHON_DEPS_CHECKED)

From 5a8e9ef2bc376883b7c0dc5eb14d7cb34c9cb084 Mon Sep 17 00:00:00 2001
From: Angus Gratton <angus@espressif.com>
Date: Wed, 31 Mar 2021 17:36:50 +1100
Subject: [PATCH 3/3] cmake: Improve the error message if the Python
 interpreter fails to run

RESULT_VARIABLE will return a string not a number in this case, so display it
for the user.
---
 tools/cmake/build.cmake | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/cmake/build.cmake b/tools/cmake/build.cmake
index a6202025b0..de7be4d5a7 100644
--- a/tools/cmake/build.cmake
+++ b/tools/cmake/build.cmake
@@ -275,8 +275,12 @@ function(__build_check_python)
         message(STATUS "Checking Python dependencies...")
         execute_process(COMMAND "${python}" "${idf_path}/tools/check_python_dependencies.py"
             RESULT_VARIABLE result)
-        if(NOT result EQUAL 0)
+        if(result EQUAL 1)
+            # check_python_dependencies returns error code 1 on failure
             message(FATAL_ERROR "Some Python dependencies must be installed. Check above message for details.")
+        elseif(NOT result EQUAL 0)
+            # means check_python_dependencies.py failed to run at all, result should be an error message
+            message(FATAL_ERROR "Failed to run Python dependency check. Python: ${python}, Error: ${result}")
         endif()
     endif()
 endfunction()