Allow overriding the extension module name in cythonize() by setting an...

Allow overriding the extension module name in cythonize() by setting an explicit name in the Extension() object.
Closes #2038.

CHANGES.rst

@@ -59,6 +59,11 @@ Features added
 Bugs fixed
 ----------
 
+* If a module name is explicitly provided for an ``Extension()`` that is compiled
+  via ``cythonize()``, it was previously ignored and replaced by the source file
+  name.  It can now be used to override the target module name, e.g. for compiling
+  prefixed accelerator modules from Python files.  (Github issue #2038)
+
 * The arguments of the ``num_threads`` parameter of parallel sections
   were not sufficiently validated and could lead to invalid C code.
   (Github issue #1957)

Cython/Build/Dependencies.py

@@ -914,6 +914,16 @@ def cythonize(module_list, exclude=None, nthreads=0, aliases=None, quiet=False,
             for dep in m.depends:
                 copy_to_build_dir(dep)
 
+        cy_sources = [
+            source for source in m.sources
+            if os.path.splitext(source)[1] in ('.pyx', '.py')]
+        if len(cy_sources) == 1:
+            # normal "special" case: believe the Extension module name to allow user overrides
+            full_module_name = m.name
+        else:
+            # infer FQMN from source files
+            full_module_name = None
+
         new_sources = []
         for source in m.sources:
             base, ext = os.path.splitext(source)
@@ -960,7 +970,8 @@ def cythonize(module_list, exclude=None, nthreads=0, aliases=None, quiet=False,
                         fingerprint = None
                     to_compile.append((
                         priority, source, c_file, fingerprint, quiet,
-                        options, not exclude_failures, module_metadata.get(m.name)))
+                        options, not exclude_failures, module_metadata.get(m.name),
+                        full_module_name))
                 new_sources.append(c_file)
                 modules_by_cfile[c_file].append(m)
             else:
@@ -1079,8 +1090,9 @@ else:
 # TODO: Share context? Issue: pyx processing leaks into pxd module
 @record_results
 def cythonize_one(pyx_file, c_file, fingerprint, quiet, options=None,
-                  raise_on_failure=True, embedded_metadata=None, progress=""):
-    from ..Compiler.Main import compile, default_options
+                  raise_on_failure=True, embedded_metadata=None, full_module_name=None,
+                  progress=""):
+    from ..Compiler.Main import compile_single, default_options
     from ..Compiler.Errors import CompileError, PyrexError
 
     if fingerprint:
@@ -1113,7 +1125,7 @@ def cythonize_one(pyx_file, c_file, fingerprint, quiet, options=None,
 
     any_failures = 0
     try:
-        result = compile([pyx_file], options)
+        result = compile_single(pyx_file, options, full_module_name=full_module_name)
         if result.num_errors > 0:
             any_failures = 1
     except (EnvironmentError, PyrexError) as e:

tests/build/cythonize_rename_ext.srctree

+PYTHON setup.py build_ext --inplace
+PYTHON -c "from pkg import b; assert b.test() == 43"
+
+######## setup.py ########
+
+from Cython.Build import cythonize
+
+from distutils.core import setup, Extension
+
+extensions = [
+    Extension('pkg.b', sources=['pkg/a.pyx', 'pkg/alib.c'],
+              include_dirs=['pkg'])
+]
+
+setup(
+  ext_modules = cythonize(extensions)
+)
+
+######## pkg/__init__.py ########
+
+######## pkg/a.pyx ########
+
+cdef extern from "alib.h":
+    int c_function(int x)
+
+def test():
+    return c_function(42)
+
+
+######## pkg/alib.c ########
+
+int c_function(int x) {
+    return x + 1;
+}
+
+######## pkg/alib.h ########
+
+int c_function(int x);