setup.py: Extra CMake Arg Control (#1199)

* `setup.py`: Extra CMake Arg Control

* EMSCRIPTEN: Skip Py Extension

Author: ax3l

CMakeLists.txt

@@ -686,7 +686,12 @@ if(openPMD_HAVE_PYTHON)
     endif()
     unset(_USE_PY_LTO)
 
-    pybind11_extension(openPMD.py)
+    if(EMSCRIPTEN)
+        set_target_properties(openPMD.py PROPERTIES
+            PREFIX "")
+    else()
+        pybind11_extension(openPMD.py)
+    endif()
     pybind11_strip(openPMD.py)
 
     set_target_properties(openPMD.py PROPERTIES CXX_VISIBILITY_PRESET "hidden"

README.md

@@ -212,6 +212,8 @@ export CMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF
 python3 -m pip install openpmd-api --no-binary openpmd-api
 ```
 
+Additional CMake options can be passed via individual environment variables, which need to be prefixed with `openPMD_CMAKE_`.
+
 ### From Source
 
 [![Source Use Case](https://img.shields.io/badge/use_case-development-brightgreen)](https://cmake.org)

docs/source/install/install.rst

@@ -115,6 +115,8 @@ For some exotic architectures and compilers, you might need to disable a compile
    # optional:                                                --user
    python3 -m pip install openpmd-api --no-binary openpmd-api
 
+Additional CMake options can be passed via individual environment variables, which need to be prefixed with ``openPMD_CMAKE_``.
+
 .. _install-cmake:
 
 .. only:: html

setup.py

@@ -79,6 +79,8 @@ def build_extension(self, ext):
             #   just as well win32 & cygwin (although Windows has no RPaths)
             cmake_args.append('-DCMAKE_INSTALL_RPATH=$ORIGIN')
 
+        cmake_args += extra_cmake_args
+
         cfg = 'Debug' if self.debug else 'Release'
         build_args = ['--config', cfg]
 
@@ -139,6 +141,16 @@ def build_extension(self, ext):
 CMAKE_INTERPROCEDURAL_OPTIMIZATION = os.environ.get(
     'CMAKE_INTERPROCEDURAL_OPTIMIZATION', None)
 
+# extra CMake arguments
+extra_cmake_args = []
+for k, v in os.environ.items():
+    extra_cmake_args_prefix = "openPMD_CMAKE_"
+    if k.startswith(extra_cmake_args_prefix) and \
+       len(k) > len(extra_cmake_args_prefix):
+        extra_cmake_args.append("-D{0}={1}".format(
+            k[len(extra_cmake_args_prefix):],
+            v))
+
 # https://cmake.org/cmake/help/v3.0/command/if.html
 if openPMD_USE_MPI.upper() in ['1', 'ON', 'TRUE', 'YES']:
     openPMD_USE_MPI = "ON"