[ASTImporter] Add test for CXXDefaultInitExpr

[teemperor]

As a side note: It seems this test case actually reveals that we don't import the body of Foo's destructor?

test/Import/cxx-default-init-expr/Inputs/S.cpp:1:8: inline function 'Foo::~Foo' is not defined
struct Foo {
       ^
test/Import/cxx-default-init-expr/Inputs/S.cpp:5:8: used here
struct S {
       ^

This doesn't make the test itself fail, so I'll fix this in an upcoming patch.

[a_sidorin]

Thanks!

As a side note: It seems this test case actually reveals that we don't import the body of Foo's destructor?

This is strange. If you manage to find the reason, please notify us!

test/Import/cxx-default-init-expr/Inputs/S.cpp

+struct Foo {
+  int i;
+};
+
+struct S {
+  int int_member = 3;
+  float float_member = 3.0f;
+  Foo class_member = Foo();
+};

test/Import/cxx-default-init-expr/test.cpp

+// RUN: clang-import-test -dump-ast -import %S/Inputs/S.cpp -expression %s | FileCheck %s
+// CHECK: CXXCtorInitializer
+// CHECK-SAME: 'int_member'
+// CHECK-SAME: 'int'
+// CHECK-NEXT: CXXDefaultInitExpr
+// CHECK-SAME: 'int'
+
+// CHECK-NEXT: CXXCtorInitializer
+// CHECK-SAME: 'float_member'
+// CHECK-SAME: 'float'
+// CHECK-NEXT: CXXDefaultInitExpr
+// CHECK-SAME: 'float'
+
+// CHECK-NEXT: CXXCtorInitializer
+// CHECK-SAME: 'class_member'
+// CHECK-SAME: 'Foo'
+// CHECK-NEXT: CXXDefaultInitExpr
+// CHECK-SAME: 'Foo'
+
+void expr() {
+  struct S s;
+}