Merge pull request #238 from robotpy/constexpr-constructor

Add testcase with constexpr constructor and trampoline

Author: virtuald

robotpy_build/autowrap/render_cls_rpy_include.py

@@ -194,7 +194,7 @@ def _render_cls_trampoline(
         r.write_trim(
             f"""
             template <typename PyTrampolineBase{ precomma(template_parameter_list) }, typename PyTrampolineCfg>
-            struct PyTrampoline_{ cls.full_cpp_name_identifier } : PyTrampolineBase, virtual py::trampoline_self_life_support {{
+            struct PyTrampoline_{ cls.full_cpp_name_identifier } : PyTrampolineBase {{
               using PyTrampolineBase::PyTrampolineBase;
         """
         )

robotpy_build/autowrap/render_pybind11.py

@@ -292,7 +292,16 @@ def cls_consts(r: RenderBuffer, cls: ClassContext):
 def cls_decl(r: RenderBuffer, cls: ClassContext):
     if cls.trampoline:
         tctx = cls.trampoline
-        r.writeln(f"using {tctx.var} = {tctx.full_cpp_name};")
+        # py::trampoline_self_life_support
+        r.write_trim(
+            f"""
+            struct {tctx.var} : {tctx.full_cpp_name}, py::trampoline_self_life_support {{
+                using RpyBase = {tctx.full_cpp_name};
+                using RpyBase::RpyBase;
+            }};
+
+        """
+        )
         r.writeln(
             f'static_assert(std::is_abstract<{tctx.var}>::value == false, "{cls.full_cpp_name} " RPYBUILD_BAD_TRAMPOLINE);'
         )

tests/cpp/rpytest/ft/__init__.py

@@ -7,6 +7,7 @@
     ClassWithFields,
     ClassWithIgnored,
     ClassWithTrampoline,
+    ConstexprTrampoline,
     DocAppendClass,
     DocAppendEnum,
     DocClass,
@@ -123,6 +124,7 @@
     "ClassWithFields",
     "ClassWithIgnored",
     "ClassWithTrampoline",
+    "ConstexprTrampoline",
     "DocAppendClass",
     "DocAppendEnum",
     "DocClass",

tests/cpp/rpytest/ft/include/trampoline.h

@@ -38,3 +38,19 @@ struct ClassWithTrampoline {
     // bug: ensure this doesn't get forwarded
     ClassWithTrampoline(const int &name) {}
 };
+
+
+struct ConstexprTrampoline {
+    constexpr ConstexprTrampoline() = default;
+    constexpr virtual ~ConstexprTrampoline() = default;
+    constexpr virtual int fn() const = 0;
+};
+
+struct ChildConstexprTrampoline : ConstexprTrampoline {
+    constexpr ChildConstexprTrampoline(int i) : something(i) {}
+    constexpr int fn() const override {
+        return 1;
+    }
+
+    int something;
+};

tests/test_ft_trampoline.py

@@ -1,4 +1,4 @@
-from rpytest.ft import ClassWithTrampoline
+from rpytest.ft import ClassWithTrampoline, ConstexprTrampoline
 
 
 def test_class_with_trampoline():
@@ -25,3 +25,7 @@ def fnWithMoveOnlyParam(self, i):
 
     c = PyClassWithTrampoline()
     assert ClassWithTrampoline.check_moveonly(c) == 8
+
+
+def test_constexpr_trampoline():
+    ConstexprTrampoline()