Meson: raise FeatureNotPresent errors instead of Import errors when dependencies are not available

conftest.py

@@ -32,7 +32,6 @@
 )
 from sage.doctest.parsing import SageDocTestParser, SageOutputChecker
 
-
 class SageDoctestModule(DoctestModule):
     """
     This is essentially a copy of `DoctestModule` from
@@ -125,15 +124,26 @@ def _find(
             checker=SageOutputChecker(),
             continue_on_failure=_get_continue_on_failure(self.config),
         )
+        # Monkey patch exception reporting to ignore FeatureNotPresentError
+        old_report_unexpected_exception = runner.report_unexpected_exception
+        def _report_unexpected_exception(self, test, example, exc_info):
+            if isinstance(exc_info[1], FeatureNotPresentError):
+                # Ignore FeatureNotPresentError
+                # (it's not an error in the doctest)
+                return
+            return old_report_unexpected_exception(self, test, example, exc_info)
+        runner.report_unexpected_exception = _report_unexpected_exception
         try:
+            print(f"Collecting doctests from { self.path }: { module }")
             for test in finder.find(module, module.__name__):
+                print(test)
                 if test.examples:  # skip empty doctests
                     yield DoctestItem.from_parent(
                         self, name=test.name, runner=runner, dtest=test
                     )
         except FeatureNotPresentError as exception:
             pytest.skip(
-                f"unable to import module { self.path } due to missing feature { exception.feature.name }"
+                f"unable to import module { self.path } due to { exception }"
             )
         except ModuleNotFoundError as exception:
             # TODO: Remove this once all optional things are using Features
@@ -175,6 +185,7 @@ def pytest_collect_file(
         # We don't allow pytests to be defined in Cython files.
         # Normally, Cython files are filtered out already by pytest and we only
         # hit this here if someone explicitly runs `pytest some_file.pyx`.
+        #return SageDoctestModule.from_parent(parent, path=file_path)
         return IgnoreCollector.from_parent(parent)
     elif file_path.suffix == ".py":
         if parent.config.option.doctest:

src/sage/algebras/fusion_rings/meson.build

@@ -35,14 +35,33 @@ extension_data_cpp = {
 }
 
 foreach name, pyx : extension_data_cpp
+  deps = [py_dep, cysignals, gmp, singular]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/algebras/fusion_rings',
     install: true,
     override_options: ['cython_language=cpp'],
     include_directories: [inc_cpython, inc_ntl, inc_numpy, inc_rings],
-    dependencies: [py_dep, cysignals, gmp, singular],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'algebras/fusion_rings',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/algebras/letterplace/meson.build

@@ -15,14 +15,33 @@ extension_data_cpp = {
 }
 
 foreach name, pyx : extension_data_cpp
+  deps = [py_dep, gmp, singular]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/algebras/letterplace',
     install: true,
     override_options: ['cython_language=cpp'],
     include_directories: [inc_cpython, inc_rings],
-    dependencies: [py_dep, gmp, singular],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'algebras/letterplace',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/algebras/quatalg/meson.build

@@ -12,14 +12,33 @@ extension_data_cpp = {
 }
 
 foreach name, pyx : extension_data_cpp
+  deps = [py_dep, flint, gmp, m, ntl]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/algebras/quatalg',
     install: true,
     override_options: ['cython_language=cpp'],
     include_directories: [inc_cpython, inc_ext, inc_flint, inc_ntl, inc_rings],
-    dependencies: [py_dep, flint, gmp, m, ntl],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'algebras/quatalg',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/calculus/meson.build

@@ -25,14 +25,33 @@ extension_data = {
 }
 
 foreach name, pyx : extension_data
+  deps = [py_dep, cysignals, gmp, gsl, interpreters_dep]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/calculus',
     install: true,
     include_directories: [inc_numpy],
-    dependencies: [py_dep, cysignals, gmp, gsl, interpreters_dep],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'calculus',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 
 subdir('transforms')

src/sage/calculus/transforms/meson.build

@@ -10,13 +10,32 @@ py.install_sources(
 extension_data = {'dwt' : files('dwt.pyx'), 'fft' : files('fft.pyx')}
 
 foreach name, pyx : extension_data
+  deps = [py_dep, cysignals, gmp, gsl]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/calculus/transforms',
     install: true,
     include_directories: [inc_gsl],
-    dependencies: [py_dep, cysignals, gmp, gsl],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'calculus/transforms',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/coding/codecan/meson.build

@@ -11,6 +11,7 @@ extension_data = {
 }
 
 foreach name, pyx : extension_data
+  deps = [py_dep, cysignals, gap, gmp]
   py.extension_module(
     name,
     sources: pyx,
@@ -22,7 +23,25 @@ foreach name, pyx : extension_data
       inc_partn_ref2,
       inc_rings,
     ],
-    dependencies: [py_dep, cysignals, gap, gmp],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'coding/codecan',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/combinat/meson.build

@@ -159,6 +159,24 @@ foreach name, pyx : extension_data
     include_directories: [inc_cpython, inc_data_structures, inc_rings],
     dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'combinat',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 
 install_subdir('chas', install_dir: sage_install_dir / 'combinat')

src/sage/combinat/posets/meson.build

@@ -23,13 +23,32 @@ extension_data = {
 }
 
 foreach name, pyx : extension_data
+  deps = [py_dep, cysignals, flint, gmp]
   py.extension_module(
     name,
     sources: pyx,
     subdir: 'sage/combinat/posets',
     install: true,
     include_directories: [inc_cpython, inc_ext, inc_flint, inc_rings],
-    dependencies: [py_dep, cysignals, flint, gmp],
+    dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'combinat/posets',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/combinat/root_system/meson.build

@@ -78,5 +78,23 @@ foreach name, pyx : extension_data
     include_directories: [inc_cpython, inc_rings],
     dependencies: deps,
   )
+
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'combinat/root_system',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 

src/sage/data_structures/meson.build

@@ -27,6 +27,7 @@ extension_data = {
 }
 
 foreach name, pyx : extension_data
+  deps = [py_dep, cysignals, flint, gmp]
   py.extension_module(
     name,
     sources: pyx,
@@ -38,13 +39,28 @@ foreach name, pyx : extension_data
       inc_flint,
       inc_rings,
     ],
-    dependencies: [py_dep, cysignals, flint, gmp],
+    dependencies: deps,
   )
+  all_deps_found = true
+  foreach dep : deps
+    if not dep.found()
+      all_deps_found = false
+      break
+    endif
+  endforeach
+  if not all_deps_found
+    configure_file(
+      input: not_available,
+      output: name + '.py',
+      install_tag: 'python-runtime',
+      install_dir: sage_install_dir / 'data_structures',
+      install: true,
+      copy: true,
+    )
+  endif
 endforeach
 
-extension_data_cpp = {
-  'pairing_heap' : files('pairing_heap.pyx'),
-}
+extension_data_cpp = {'pairing_heap' : files('pairing_heap.pyx')}
 
 foreach name, pyx : extension_data_cpp
   py.extension_module(