fix: support CMake 3.15+ (#2)

* fix: support CMake 3.15+

See #1

* ci: add conda & wheel test, fix output location for conda

.github/dependabot.yml

+version: 2
+updates:
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
+    ignore:
+      # Offical actions have moving tags like v1
+      # that are used, so they don't need updates here
+      - dependency-name: "actions/*"

.github/workflows/conda.yml

+name: Conda
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        platform: [ubuntu-latest, windows-2016, macos-latest]
+        python-version: ["3.6", "3.8"]
+
+    runs-on: ${{ matrix.platform }}
+
+    # The setup-miniconda action needs this to activate miniconda
+    defaults:
+      run:
+        shell: "bash -l {0}"
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Get conda
+        uses: conda-incubator/setup-miniconda@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+          channels: conda-forge
+          
+      - name: Prepare
+        run: conda install conda-build conda-verify
+
+      - name: Build
+        run: conda build conda.recipe
+
+      - name: Install
+        run: conda install -c ${CONDA_PREFIX}/conda-bld/ scikit_build_example
+
+      - name: Test
+        run: python tests/test.py

CMakeLists.txt

-cmake_minimum_required(VERSION 3.18)
+cmake_minimum_required(VERSION 3.15...3.18)
 
 project(scikit_build_example VERSION "0.0.1")
 
-# Define CMAKE_INSTALL_xxx: LIBDIR, INCLUDEDIR
-include(GNUInstallDirs)
-
 # Currently, Scikit-build does not support FindPython, so we convert the
 # provided hints ourselves.
 if(SKBUILD)
   set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
   set(Python_INCLUDE_DIR "${PYTHON_INCLUDE_DIR}")
   set(Python_LIBRARY "${PYTHON_LIBRARY}")
+  set(DUMMY "${PYTHON_VERSION_STRING}")  # Not needed, silences a warning
 endif()
 
-set(Python_FIND_IMPLEMENTATIONS CPython PyPy)
+set(Python_FIND_IMPLEMENTATIONS CPython PyPy)  # PyPy requires 3.18
 find_package(Python REQUIRED COMPONENTS Interpreter Development)
 
 # Scikit-Build does not add your site-packages to the search path automatically,
-# so we need to add it here.
+# so we need to add it _or_ the pybind11 specific directory here.
 execute_process(
   COMMAND
     "${Python_EXECUTABLE}" -c
-    "import skbuild, os; print(os.path.dirname(os.path.dirname(skbuild.__file__)))"
-  OUTPUT_VARIABLE _tmp_sitepackages
-  OUTPUT_STRIP_TRAILING_WHITESPACE COMMAND_ECHO STDOUT ECHO_OUTPUT_VARIABLE
-  ECHO_ERROR_VARIABLE)
-list(APPEND CMAKE_PREFIX_PATH "${_tmp_sitepackages}")
+    "import pybind11; print(pybind11.get_cmake_dir())"
+  OUTPUT_VARIABLE _tmp_dir
+  OUTPUT_STRIP_TRAILING_WHITESPACE COMMAND_ECHO STDOUT)
+list(APPEND CMAKE_PREFIX_PATH "${_tmp_dir}")
 
 # Now we can find pybind11
 find_package(pybind11 CONFIG REQUIRED)

README.md

-python_example
+scikit_build_example
 ==============
 
 [![Gitter][gitter-badge]][gitter-link]
-[![Wheels Actions Status][actions-pip-badge]][actions-pip-link]
+
+|      CI              | status |
+|----------------------|--------|
+| conda.recipe         | [![Conda Actions Status][actions-conda-badge]][actions-conda-link] |
+| pip builds           | [![Pip Actions Status][actions-pip-badge]][actions-pip-link] |
+
+
+
+An example project built with [pybind11](https://github.com/pybind/pybind11) and scikit-build.
+
+
 
 [gitter-badge]:            https://badges.gitter.im/pybind/Lobby.svg
 [gitter-link]:             https://gitter.im/pybind/Lobby
-[actions-pip-link]:     https://github.com/pybind/scikit_build_example/actions?query=workflow%3APip
-[actions-pip-badge]:    https://github.com/pybind/scikit_build_example/workflows/Pip/badge.svg
-
-An example project built with [pybind11](https://github.com/pybind/pybind11).
+[actions-badge]:           https://github.com/pybind/scikit_build_example/workflows/Tests/badge.svg
+[actions-conda-link]:      https://github.com/pybind/scikit_build_example/actions?query=workflow%3A%22Conda
+[actions-conda-badge]:     https://github.com/pybind/scikit_build_example/workflows/Conda/badge.svg
+[actions-pip-link]:        https://github.com/pybind/scikit_build_example/actions?query=workflow%3A%22Pip
+[actions-pip-badge]:       https://github.com/pybind/scikit_build_example/workflows/Pip/badge.svg
+[actions-wheels-link]:     https://github.com/pybind/scikit_build_example/actions?query=workflow%3AWheels
+[actions-wheels-badge]:    https://github.com/pybind/scikit_build_example/workflows/Wheels/badge.svg
 
 Installation
 ------------
@@ -19,7 +32,7 @@ Installation
  - clone this repository
  - `pip install ./scikit_build_example`
 
-**On Windows (Requires Visual Studio 2017)**
+**On Windows**
 
  - For Python 3.5+:
      - clone this repository
@@ -45,8 +58,8 @@ Test call
 ---------
 
 ```python
-import python_example
-python_example.add(1, 2)
+import scikit_build_example
+scikit_build_example.add(1, 2)
 ```
 
 [`cibuildwheel`]:          https://cibuildwheel.readthedocs.io

conda.recipe/meta.yaml

+package:
+  name: scikit_build_example
+  version: 0.0.1
+
+source:
+  path: ..
+
+build:
+  number: 0
+  script: python -m pip install . -vvv
+
+requirements:
+  build:
+    - {{ compiler('cxx') }}
+
+  host:
+    - python
+    - pip
+    - pybind11 >=2.6.0
+    - scikit-build
+    - cmake >=3.18
+    - ninja
+
+  run:
+    - python
+
+
+test:
+  imports:
+    - scikit_build_example
+  source_files:
+    - tests
+  commands:
+    - python tests/test.py
+
+about:
+  summary: An example project built with pybind11 and scikit-build.
+  license_file: LICENSE

setup.py

@@ -15,7 +15,7 @@ except ImportError:
     raise
 
 setup(
-    name="scikit-build-example",
+    name="scikit_build_example",
     version="0.0.1",
     description="a minimal example package (with pybind11)",
     author="Henry Schreiner",