v4: Further fixes for f2py, macos, and spack

CHANGELOG.md

@@ -17,6 +17,30 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Deprecated
 
+## [4.34.0] - 2026-03-04
+
+### Fixed
+
+- Fixed f2py and f2py3 detection in Spack environments where the `f2py`
+  executable lives in the `py-numpy` package's `bin/` directory rather than
+  alongside the Python interpreter. `FindF2PY.cmake` and `FindF2PY3.cmake` now
+  ask Python directly (`import numpy.f2py`) to locate the correct `f2py`
+  binary. A two-pass search is used: the preferred locations (Python `bin/` and
+  numpy-derived `bin/`) are checked first with `NO_DEFAULT_PATH`, then a normal
+  `PATH` search is used as a fallback to preserve behaviour on non-Spack
+  (e.g. module-based) systems.
+- Fixed `find_package(Python3)` picking up a different Python 3 interpreter
+  (e.g. a newer Homebrew Python) instead of the one already found by
+  `find_package(Python)` in Spack environments. `esma_python.cmake` now pins
+  `Python3_EXECUTABLE` to `Python_EXECUTABLE` when `find_package(Python)` has
+  already resolved a Python 3 interpreter, ensuring both find the same Python.
+
+### Changed
+
+- Added `Python_FIND_VIRTUALENV FIRST` and `Python3_FIND_VIRTUALENV FIRST` to
+  `esma_python.cmake` so that an active Spack `python-venv` on `PATH` is
+  preferred over system or framework Pythons.
+
 ## [4.33.1] - 2026-03-03
 
 ### Fixed

python/esma_python.cmake

@@ -16,6 +16,9 @@ endif ()
 set(Python_FIND_STRATEGY LOCATION)
 set(Python_FIND_UNVERSIONED_NAMES FIRST)
 set(Python_FIND_FRAMEWORK LAST)
+# FIRST: respect an active virtualenv (e.g. Spack python-venv) on PATH before
+# falling back to system/Homebrew Python.
+set(Python_FIND_VIRTUALENV FIRST)
 find_package(Python COMPONENTS Interpreter)
 list (APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/f2py")
 include (esma_find_python_module)
@@ -28,6 +31,17 @@ endif ()
 set(Python3_FIND_STRATEGY LOCATION)
 set(Python3_FIND_UNVERSIONED_NAMES FIRST)
 set(Python3_FIND_FRAMEWORK LAST)
+# FIRST: respect an active virtualenv (e.g. Spack python-venv) on PATH before
+# falling back to system/Homebrew Python.
+set(Python3_FIND_VIRTUALENV FIRST)
+# If find_package(Python) already found a Python 3 interpreter (e.g. via
+# Python_ROOT_DIR set by a Spack environment), pin Python3 to the exact same
+# executable so it doesn't wander off and find a different Python 3 (e.g. a
+# newer Homebrew Python). Python3_EXECUTABLE bypasses all discovery logic.
+if (Python_EXECUTABLE AND Python_VERSION_MAJOR EQUAL 3)
+  message(DEBUG "[esma_python]: Pinning Python3_EXECUTABLE to ${Python_EXECUTABLE} (already found by find_package(Python))")
+  set(Python3_EXECUTABLE "${Python_EXECUTABLE}")
+endif ()
 find_package(Python3 COMPONENTS Interpreter)
 list (APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/f2py3")
 include (esma_find_python3_module)

python/f2py/FindF2PY.cmake

@@ -41,15 +41,49 @@ message(DEBUG "[F2PY]: Searching for f2py executable associated with Python_EXEC
 get_filename_component(Python_EXECUTABLE_DIR ${Python_EXECUTABLE} DIRECTORY)
 message(DEBUG "[F2PY]: Python executable directory: ${Python_EXECUTABLE_DIR}")
 
+# In Spack environments, f2py lives in the py-numpy package's bin dir, which is
+# separate from the Python interpreter's bin dir. Ask Python/numpy directly for
+# the path to f2py so we always get the one matching the active numpy.
+execute_process(
+  COMMAND "${Python_EXECUTABLE}" -c "import numpy.f2py; import os; print(os.path.dirname(numpy.f2py.__file__))"
+  OUTPUT_VARIABLE _numpy_f2py_dir
+  ERROR_QUIET
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+if (_numpy_f2py_dir)
+  # numpy.f2py package dir is e.g. .../lib/pythonX.Y/site-packages/numpy/f2py
+  # Walking up 5 levels reaches the package prefix; bin/ lives alongside lib/.
+  # Layout: <prefix>/bin/f2py
+  #                  lib/pythonX.Y/site-packages/numpy/f2py   <- _numpy_f2py_dir
+  get_filename_component(_numpy_bin_dir "${_numpy_f2py_dir}/../../../../.." ABSOLUTE)
+  set(_numpy_bin_dir "${_numpy_bin_dir}/bin")
+  message(DEBUG "[F2PY]: numpy f2py package dir: ${_numpy_f2py_dir}")
+  message(DEBUG "[F2PY]: numpy-derived bin hint: ${_numpy_bin_dir}")
+endif ()
+
 find_program(F2PY_EXECUTABLE
   NAMES "f2py${Python_VERSION_MAJOR}"
         "f2py${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}"
         "f2py-${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}"
         "f2py"
   PATHS ${Python_EXECUTABLE_DIR}
+        ${_numpy_bin_dir}
   HINTS ${Python_EXECUTABLE_DIR}
+        ${_numpy_bin_dir}
+  NO_DEFAULT_PATH
 )
 
+# If not found in the preferred locations, fall back to a normal PATH search.
+# This handles non-Spack environments where f2py may be elsewhere on PATH.
+if (NOT F2PY_EXECUTABLE)
+  find_program(F2PY_EXECUTABLE
+    NAMES "f2py${Python_VERSION_MAJOR}"
+          "f2py${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}"
+          "f2py-${Python_VERSION_MAJOR}.${Python_VERSION_MINOR}"
+          "f2py"
+  )
+endif ()
+
 message(DEBUG "[F2PY]: Found f2py executable: ${F2PY_EXECUTABLE}")
 
 # Now as a sanity check, we need to make sure that the f2py executable is

python/f2py3/FindF2PY3.cmake

@@ -41,15 +41,49 @@ message(DEBUG "[F2PY3]: Searching for f2py3 executable associated with Python3_E
 get_filename_component(Python3_EXECUTABLE_DIR ${Python3_EXECUTABLE} DIRECTORY)
 message(DEBUG "[F2PY3]: Python3 executable directory: ${Python3_EXECUTABLE_DIR}")
 
+# In Spack environments, f2py lives in the py-numpy package's bin dir, which is
+# separate from the Python interpreter's bin dir. Ask Python/numpy directly for
+# the path to f2py so we always get the one matching the active numpy.
+execute_process(
+  COMMAND "${Python3_EXECUTABLE}" -c "import numpy.f2py; import os; print(os.path.dirname(numpy.f2py.__file__))"
+  OUTPUT_VARIABLE _numpy_f2py_dir
+  ERROR_QUIET
+  OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+if (_numpy_f2py_dir)
+  # numpy.f2py package dir is e.g. .../lib/pythonX.Y/site-packages/numpy/f2py
+  # Walking up 5 levels reaches the package prefix; bin/ lives alongside lib/.
+  # Layout: <prefix>/bin/f2py
+  #                  lib/pythonX.Y/site-packages/numpy/f2py   <- _numpy_f2py_dir
+  get_filename_component(_numpy_bin_dir "${_numpy_f2py_dir}/../../../../.." ABSOLUTE)
+  set(_numpy_bin_dir "${_numpy_bin_dir}/bin")
+  message(DEBUG "[F2PY3]: numpy f2py package dir: ${_numpy_f2py_dir}")
+  message(DEBUG "[F2PY3]: numpy-derived bin hint: ${_numpy_bin_dir}")
+endif ()
+
 find_program(F2PY3_EXECUTABLE
   NAMES "f2py${Python3_VERSION_MAJOR}"
         "f2py${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}"
         "f2py-${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}"
         "f2py"
   PATHS ${Python3_EXECUTABLE_DIR}
+        ${_numpy_bin_dir}
   HINTS ${Python3_EXECUTABLE_DIR}
+        ${_numpy_bin_dir}
+  NO_DEFAULT_PATH
 )
 
+# If not found in the preferred locations, fall back to a normal PATH search.
+# This handles non-Spack environments where f2py may be elsewhere on PATH.
+if (NOT F2PY3_EXECUTABLE)
+  find_program(F2PY3_EXECUTABLE
+    NAMES "f2py${Python3_VERSION_MAJOR}"
+          "f2py${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}"
+          "f2py-${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}"
+          "f2py"
+  )
+endif ()
+
 message(DEBUG "[F2PY3]: Found f2py3 executable: ${F2PY3_EXECUTABLE}")
 
 # Now as a sanity check, we need to make sure that the f2py3 executable is