Include .h and _api.h files in target overwrite check.

See https://github.com/cython/cython/issues/4177
See https://github.com/cython/cython/pull/4178

Cython/Compiler/ModuleNode.py

@@ -179,6 +179,14 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
                     return 1
         return 0
 
+    def assure_safe_target(self, path, allow_failed=False):
+        # Check for a common gotcha for new users: naming your .pyx file after the .c file you want to wrap
+        if not is_cython_generated_file(path, allow_failed=allow_failed, if_not_found=True):
+            # Raising a fatal CompileError instead of calling error() to prevent castrating an existing file.
+            raise CompileError(
+                self.pos, 'The output file already exists and does not look like it was generated by Cython: "%s"' %
+                          os.path.basename(path))
+
     def generate_h_code(self, env, options, result):
         def h_entries(entries, api=0, pxd=0):
             return [entry for entry in entries
@@ -189,8 +197,11 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         h_vars = h_entries(env.var_entries)
         h_funcs = h_entries(env.cfunc_entries)
         h_extension_types = h_entries(env.c_class_entries)
+
         if h_types or h_vars or h_funcs or h_extension_types:
             result.h_file = replace_suffix_encoded(result.c_file, ".h")
+            self.assure_safe_target(result.h_file)
+
             h_code_writer = Code.CCodeWriter()
             c_code_config = generate_c_code_config(env, options)
             globalstate = Code.GlobalState(h_code_writer, self, c_code_config)
@@ -299,8 +310,11 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         api_vars = api_entries(env.var_entries)
         api_funcs = api_entries(env.cfunc_entries)
         api_extension_types = api_entries(env.c_class_entries)
+
         if api_vars or api_funcs or api_extension_types:
             result.api_file = replace_suffix_encoded(result.c_file, "_api.h")
+            self.assure_safe_target(result.api_file)
+
             h_code = Code.CCodeWriter()
             c_code_config = generate_c_code_config(env, options)
             Code.GlobalState(h_code, self, c_code_config)
@@ -401,13 +415,7 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         i_code.dedent()
 
     def generate_c_code(self, env, options, result):
-        # Check for a common gotcha for new users: naming your .pyx file after the .c file you want to wrap
-        if not is_cython_generated_file(result.c_file, allow_failed=True, if_not_found=True):
-            # Raising a fatal CompileError instead of calling error() to prevent castrating an existing file.
-            raise CompileError(
-                self.pos, 'The output file already exists and does not look like it was generated by Cython: "%s"' %
-                os.path.basename(result.c_file))
-
+        self.assure_safe_target(result.c_file, allow_failed=True)
         modules = self.referenced_modules
 
         if Options.annotate or options.annotate:

tests/run/existing_output_files.srctree

@@ -12,7 +12,7 @@ from Cython.Build.Dependencies import cythonize
 # Make sure the source files are newer than the .c files, so that cythonize() regenerates them.
 files = {}
 for source_file in sorted(os.listdir(os.getcwd())):
-    if 'module' in source_file and not source_file.endswith(".c"):
+    if 'module' in source_file and (source_file.endswith(".pyx") or source_file.endswith(".py")):
         c_file = files[source_file] = os.path.splitext(source_file)[0] + ".c"
         os.utime(source_file, None)
         assert not os.path.exists(c_file) or os.path.getmtime(source_file) >= os.path.getmtime(c_file)
@@ -20,35 +20,45 @@ for source_file in sorted(os.listdir(os.getcwd())):
 for source_file, c_file in files.items():
     print("Testing:", source_file, c_file)
     assert is_cython_generated_file(c_file, allow_failed=True, if_not_found=True)
+
+    # cythonizing should (re)generate the file
+    cythonize(source_file, language_level=3)
+    assert is_cython_generated_file(c_file, if_not_found=False)
+    assert os.path.getmtime(source_file) <= os.path.getmtime(c_file)
+
+    # calling cythonize again should not rewrite the file
+    # (not asserting this here, but at least it shouldn't fail)
     cythonize(source_file, language_level=3)
     assert is_cython_generated_file(c_file, if_not_found=False)
     assert os.path.getmtime(source_file) <= os.path.getmtime(c_file)
 
+
 # But overwriting an unknown file should fail, even when requested multiple times.
 for source_file in [
         "refuse_to_overwrite.pyx",
-        "refuse_to_overwrite.pyx",
-        "refuse_to_overwrite.pyx",
-        #
-        "refuse_to_overwrite.py",
         "refuse_to_overwrite.py",
-        "refuse_to_overwrite.py",
-        #
-        "compile_failure.pyx",
-        "compile_failure.pyx",
         "compile_failure.pyx",
+        "refuse_to_overwrite_header.pyx",
+        "refuse_to_overwrite_api_header.pyx",
 ]:
-    os.utime(source_file, None)
-    c_file = os.path.splitext(source_file)[0] + ".c"
-    assert not is_cython_generated_file(c_file)
-    try:
-        print("Testing:", source_file)
-        cythonize(source_file, language_level=3)
-    except CompileError:
-        print("REFUSED to overwrite %s, OK" % c_file)
-        assert not is_cython_generated_file(c_file)
+    if 'api_header' in source_file:
+        target_file = os.path.splitext(source_file)[0] + "_api.h"
+    elif 'header' in source_file:
+        target_file = os.path.splitext(source_file)[0] + ".h"
     else:
-        assert False, "FAILURE: Existing output file was overwritten for source file %s" % source_file
+        target_file = os.path.splitext(source_file)[0] + ".c"
+
+    for _ in range(3):
+        os.utime(source_file, None)
+        assert not is_cython_generated_file(target_file)
+        try:
+            print("Testing:", source_file)
+            cythonize(source_file, language_level=3)
+        except CompileError:
+            print("REFUSED to overwrite %s, OK" % target_file)
+            assert not is_cython_generated_file(target_file)
+        else:
+            assert False, "FAILURE: Existing output file was overwritten for source file %s" % source_file
 
 
 ######## pymodule.c ########
@@ -114,3 +124,56 @@ Do not overwrite an unknown output file even on compile failures.
 """
 
 Not Python syntax!
+
+
+
+######## write_module_header.pyx ########
+
+cdef public int func():
+    return 1
+
+
+######## overwrite_module_header.c ########
+/* Generated by Cython 0.8.15 */
+
+######## overwrite_module_header.pyx ########
+
+cdef public int func():
+    return 1
+
+
+######## refuse_to_overwrite_header.h ########
+static int external_function(int x) {
+    return x + 1;
+}
+
+######## refuse_to_overwrite_header.pyx ########
+
+cdef public int func():
+    return 1
+
+
+######## write_module_api_header.pyx ########
+
+cdef api int func():
+    return 1
+
+
+######## overwrite_module_api_header.c ########
+/* Generated by Cython 0.8.15 */
+
+######## overwrite_module_api_header.pyx ########
+
+cdef public int func():
+    return 1
+
+
+######## refuse_to_overwrite_api_header_api.h ########
+static int external_function(int x) {
+    return x + 1;
+}
+
+######## refuse_to_overwrite_api_header.pyx ########
+
+cdef api int func():
+    return 1