getting the build process to recognize a lower python version

[heal-research]

getting the build process to recognize a lower python version

[lacava]

thanks for the help! the least intrusive option turned out to be building with -DPython3_FIND_VIRTUALENV=ONLY

SOURCE_DATE_EPOCH=`date +%s` cmake .. -DCMAKE_BUILD_TYPE=Release  -DBUILD_PYBIND=ON -DUSE_OPENLIBM=ON -DUSE_SINGLE_PRECISION=ON -DCERES_TINY_SOLVER=ON -DPython3_FIND_VIRTUALENV=ONLY

[foolnotion]

Hmm, maybe we can use pkg-config as a workaround. Could you try this patch:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d5af4c8..80f2c3c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,9 +20,9 @@ find_package(Eigen3)
 find_package(Ceres)
 find_package(Threads)
 find_package(TBB)
-find_package(Python3 COMPONENTS Development Interpreter)
 find_package(pybind11)
 find_package(doctest)
+find_package(PkgConfig REQUIRED)
 
 # operon library
 set_package_properties(Git     PROPERTIES TYPE REQUIRED)
@@ -36,7 +36,7 @@ set_package_properties(doctest PROPERTIES TYPE OPTIONAL) # unit tests
 set_package_properties(cxxopts PROPERTIES TYPE OPTIONAL) # command-line parser
 
 # python binding
-set_package_properties(Python3 PROPERTIES TYPE OPTIONAL)
+pkg_check_modules(Python3 python-3.7 REQUIRED)
 set_package_properties(pybind11 PROPERTIES TYPE OPTIONAL)
 
 # get revision information from git

My hope is that pkg-config inside the conda environment will find the correct python version.

EDIT: I tested this by forcing python-3.7 inside the conda env, it works, but CMake is no longer able to autodetec the install path, so it should be specified explicitly:

CC=gcc-9 CXX=g++-9 cmake .. -DCMAKE_BUILD_TYPE=Release -DUSE_SINGLE_PRECISION=ON -DBUILD_PYBIND=ON -DUSE_OPENLIBM=ON -DCERES_TINY_SOLVER=ON -DCMAKE_INSTALL_PREFIX=$CONDA_PREFIX/lib/python3.7/site-packages/

This works for now, however I am a bit reluctant to commit this fix since it still seems more like a workaround.

EDIT2:
Another couple options that might work:

• Use find_package(Python3 3.x.x EXACT REQUIRED) to match an exact version.
• Use -DPython3_ROOT_DIR to tell CMake where to find the Python3 installation