BUG: Fix generated sources not being included as dependencies in cython transpilation

mesonbuild/backend/ninjabackend.py

@@ -1698,6 +1698,8 @@ class NinjaBackend(backends.Backend):
 
         ext = target.get_option(OptionKey('language', machine=target.for_machine, lang='cython'))
 
+        pyx_sources = []  # Keep track of sources we're adding to build
+
         for src in target.get_sources():
             if src.endswith('.pyx'):
                 output = os.path.join(self.get_target_private_dir(target), f'{src}.{ext}')
@@ -1711,9 +1713,11 @@ class NinjaBackend(backends.Backend):
                 self.add_build(element)
                 # TODO: introspection?
                 cython_sources.append(output)
+                pyx_sources.append(element)
             else:
                 static_sources[src.rel_to_builddir(self.build_to_src)] = src
 
+        header_deps = []  # Keep track of generated headers for those sources
         for gen in target.get_generated_sources():
             for ssrc in gen.get_outputs():
                 if isinstance(gen, GeneratedList):
@@ -1730,10 +1734,20 @@ class NinjaBackend(backends.Backend):
                         [ssrc])
                     element.add_item('ARGS', args)
                     self.add_build(element)
+                    pyx_sources.append(element)
                     # TODO: introspection?
                     cython_sources.append(output)
                 else:
                     generated_sources[ssrc] = mesonlib.File.from_built_file(gen.get_subdir(), ssrc)
+                    # Following logic in L883-900 where we determine whether to add generated source
+                    # as a header(order-only) dep to the .so compilation rule
+                    if not self.environment.is_source(ssrc) and \
+                            not self.environment.is_object(ssrc) and \
+                            not self.environment.is_library(ssrc) and \
+                            not modules.is_module_library(ssrc):
+                        header_deps.append(ssrc)
+        for source in pyx_sources:
+            source.add_orderdep(header_deps)
 
         return static_sources, generated_sources, cython_sources
 

test cases/cython/2 generated sources/includestuff.pyx

@@ -0,0 +1 @@
+include "stuff.pxi"

test cases/cython/2 generated sources/meson.build

@@ -6,6 +6,7 @@ project(
 py_mod = import('python')
 py3 = py_mod.find_installation('python3')
 py3_dep = py3.dependency(required : false)
+fs = import('fs')
 if not py3_dep.found()
   error('MESON_SKIP_TEST: Python library not found.')
 endif
@@ -70,6 +71,25 @@ test(
   env : ['PYTHONPATH=' + meson.current_build_dir()]
 )
 
+stuff_pxi = fs.copyfile(
+  'stuff.pxi.in',
+  'stuff.pxi'
+)
+
+# Need to copy the cython source to the build directory
+# since meson can only generate the .pxi there
+includestuff_pyx = fs.copyfile(
+  'includestuff.pyx'
+)
+
+stuff_pxi_dep = declare_dependency(sources: stuff_pxi)
+
+includestuff_ext = py3.extension_module(
+  'includestuff',
+  includestuff_pyx,
+  dependencies: stuff_pxi_dep
+)
+
 subdir('libdir')
 
 test(

test cases/cython/2 generated sources/stuff.pxi.in

@@ -0,0 +1,2 @@
+def func():
+    print("Hello world")

unittests/allplatformstests.py

@@ -833,6 +833,32 @@ class AllPlatformTests(BasePlatformTests):
         self.build(target=('barprog' + exe_suffix))
         self.assertPathExists(exe2)
 
+    def test_build_generated_pyx_directly(self):
+        # Check that the transpile stage also includes
+        # dependencies for the compilation stage as dependencies
+        testdir = os.path.join("test cases/cython", '2 generated sources')
+        env = get_fake_env(testdir, self.builddir, self.prefix)
+        try:
+            detect_compiler_for(env, "cython", MachineChoice.HOST)
+        except EnvironmentException:
+            raise SkipTest("Cython is not installed")
+        self.init(testdir)
+        # Need to get the full target name of the pyx.c target
+        # (which is unfortunately not provided by introspection :( )
+        # We'll need to dig into the generated sources
+        targets = self.introspect('--targets')
+        name = None
+        for target in targets:
+            for target_sources in target["target_sources"]:
+                for generated_source in target_sources["generated_sources"]:
+                    if "includestuff.pyx.c" in generated_source:
+                        name = generated_source
+                        break
+        # Split the path (we only want the includestuff.cpython-blahblahblah)
+        name = os.path.normpath(name).split("/")[-2:]
+        name = "/".join(name)  # Glue list into a string
+        self.build(target=name)
+
     def test_internal_include_order(self):
         if mesonbuild.environment.detect_msys2_arch() and ('MESON_RSP_THRESHOLD' in os.environ):
             raise SkipTest('Test does not yet support gcc rsp files on msys2')