Test and fix for the case where ffi.embedding_api() is called but

does not list any `extern "Python"` function

5 files changed, 26 insertions, 5 deletions

diff --git a/cffi/_embedding.h b/cffi/_embedding.h
index e863d85..4a42cbb 100644
--- a/cffi/_embedding.h
+++ b/cffi/_embedding.h
@@ -22,7 +22,8 @@ extern "C" {
 
    * _cffi_call_python_org, which on CPython is actually part of the
      _cffi_exports[] array, is the function pointer copied from
-     _cffi_backend.
+     _cffi_backend.  If _cffi_start_python() fails, then this is set
+     to NULL; otherwise, it should never be NULL.
 
    After initialization is complete, both are equal.  However, the
    first one remains equal to &_cffi_start_and_call_python until the
diff --git a/cffi/recompiler.py b/cffi/recompiler.py
index 86b37d7..16a7078 100644
--- a/cffi/recompiler.py
+++ b/cffi/recompiler.py
@@ -406,9 +406,8 @@ class Recompiler:
         else:
             prnt('  NULL,  /* no includes */')
         prnt('  %d,  /* num_types */' % (len(self.cffi_types),))
-        flags = 0
-        if self._num_externpy:
-            flags |= 1     # set to mean that we use extern "Python"
+        # set 'flags' to 1 in embedding mode, 0 otherwise
+        flags = int(self.ffi._embedding is not None)
         prnt('  %d,  /* flags */' % flags)
         prnt('};')
         prnt()
diff --git a/testing/embedding/empty-test.c b/testing/embedding/empty-test.c
new file mode 100644
index 0000000..b00dd50
--- /dev/null
+++ b/testing/embedding/empty-test.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+void initialize_my_empty_cffi(void);
+
+int main(void)
+{
+    initialize_my_empty_cffi();
+    printf("OK\n");
+    return 0;
+}
+
diff --git a/testing/embedding/empty.py b/testing/embedding/empty.py
index aa8d830..1093505 100644
--- a/testing/embedding/empty.py
+++ b/testing/embedding/empty.py
@@ -4,7 +4,14 @@ ffi = cffi.FFI()
 
 ffi.embedding_api("")
 
-ffi.set_source("_empty_cffi", "")
+ffi.set_source("_empty_cffi", """
+void initialize_my_empty_cffi(void) {
+    if (cffi_start_python() != 0) {
+        printf("oops, cffi_start_python() returned non-0\\n");
+        abort();
+    }
+}
+""")
 
 fn = ffi.compile(verbose=True)
 print('FILENAME: %s' % (fn,))
diff --git a/testing/embedding/test_basic.py b/testing/embedding/test_basic.py
index 8d2e776..b29afd2 100644
--- a/testing/embedding/test_basic.py
+++ b/testing/embedding/test_basic.py
@@ -180,6 +180,9 @@ if sys.platform == 'win32':
 class TestBasic(EmbeddingTests):
     def test_empty(self):
         empty_cffi = self.prepare_module('empty')
+        self.compile('empty-test', [empty_cffi])
+        output = self.execute('empty-test')
+        assert output == 'OK\n'
 
     def test_basic(self):
         add1_cffi = self.prepare_module('add1')