issue 147: force-compute nested structs before parent structs

[arigo]

Occurs mainly in out-of-line ABI mode.

[mattip]

Any idea how to port this to PyPy? The code there is different: there is no explicit CT_IS_OPAQUE flag. Even more complicated: I am not sure how to write a untranslated test for this.

[arigo]

The PyPy logic is different, so maybe there isn't anything to fix. Does the original test case in #147 work on a translated PyPy?

[arigo]

Found the same logic in complete_struct_or_union() in newtype.py, but also found comments in the class W_CTypeStructOrUnion that make me think that PyPy, unlike CFFI on CPython, doesn't use ftype->ct_size < 0 if the struct type is lazy. If that's correct, then there is indeed nothing to fix.

[mattip]

The test fails on py3.10. I tried various incantations to try to cause the struct to be evaluated when size == -2, which I think is supposed to be "lazy", but failed. I also could not figure out how to run the test untranslated.

[arigo]

Here's a blind attempt at writing an untranslated test (completely untested):

diff -r 2eefecd93d0f pypy/module/_cffi_backend/test/test_re_python.py
--- a/pypy/module/_cffi_backend/test/test_re_python.py  Mon Oct 16 08:36:02 2023 +0200
+++ b/pypy/module/_cffi_backend/test/test_re_python.py  Sun Dec 29 18:54:07 2024 +0100
@@ -32,6 +32,7 @@
         struct foo_s;
         typedef struct bar_s { int x; signed char a[]; } bar_t;
         enum foo_e { AA, BB, CC };
+        struct B { struct C* c; }; struct C { struct B b; };

         void init_test_re_python(void) { }      /* windows hack */
         void PyInit__test_re_python(void) { }   /* windows hack */
@@ -270,3 +271,15 @@

         err = lib1.dlclose(handle)
         assert err == 0
+
+    def test_rec_structs_1(self):
+        self.fix_path()
+        from re_python_pysrc import ffi
+        sz = ffi.sizeof("struct B")
+        assert sz == ffi.sizeof("int *")
+
+    def test_rec_structs_2(self):
+        self.fix_path()
+        from re_python_pysrc import ffi
+        sz = ffi.sizeof("struct C")
+        assert sz == ffi.sizeof("int *")

[mattip]

Yup, thanks @arigo that worked. The test and fix are in this commit