gen: Don't generate tests for empty structs or classes

Since the reported size is 1 byte even though it should be 0.

4 files changed, 30 insertions, 1 deletions

diff --git a/src/gen.rs b/src/gen.rs
index a6ab7118..d4bd277c 100644
--- a/src/gen.rs
+++ b/src/gen.rs
@@ -1068,6 +1068,7 @@ fn cstruct_to_rs(ctx: &mut GenCtx, name: &str, ci: CompInfo) -> Vec<P<ast::Item>
         }));
     }
 
+    let field_count = fields.len();
     let variant_data = if fields.is_empty() {
         ast::VariantData::Unit(ast::DUMMY_NODE_ID)
     } else {
@@ -1136,7 +1137,17 @@ fn cstruct_to_rs(ctx: &mut GenCtx, name: &str, ci: CompInfo) -> Vec<P<ast::Item>
     }
 
     // Template args have incomplete type in general
-    if ci.args.is_empty() {
+    //
+    // XXX if x is a class without members, C++ still will report
+    // sizeof(x) == 1, since it requires to be adressable.
+    //
+    // We maybe should add a dummy byte if it's the case, but...
+    // That could play wrong with inheritance.
+    //
+    // So for now don't generate a test if the struct/class is empty
+    // or has only empty bases.
+    if ci.args.is_empty() && field_count > 0 &&
+       (ci.has_nonempty_base || ci.base_members < field_count) {
         extra.push(mk_test_fn(ctx, name, &layout));
     }
 
diff --git a/src/parser.rs b/src/parser.rs
index d0d23895..538d5d9c 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -685,6 +685,7 @@ fn visit_composite(cursor: &Cursor, parent: &Cursor,
                 ci.members.push(CompMember::Field(field));
             }
             if let TComp(ref info) = ty {
+                ci.has_nonempty_base |= !info.borrow().members.is_empty();
                 ci.typedefs.extend(info.borrow().typedefs.clone().into_iter());
             }
             ci.base_members += 1;
diff --git a/src/types.rs b/src/types.rs
index 1207d309..166457ec 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -283,6 +283,7 @@ pub struct CompInfo {
     pub ref_template: Option<Type>,
     pub has_vtable: bool,
     pub has_destructor: bool,
+    pub has_nonempty_base: bool,
     pub hide: bool,
     pub base_members: usize,
     pub layout: Layout,
@@ -318,6 +319,7 @@ impl CompInfo {
             ref_template: None,
             has_vtable: false,
             has_destructor: false,
+            has_nonempty_base: false,
             hide: false,
             base_members: 0,
             layout: layout,
diff --git a/tests/headers/class_no_members.hpp b/tests/headers/class_no_members.hpp
new file mode 100644
index 00000000..a1f4d2a4
--- /dev/null
+++ b/tests/headers/class_no_members.hpp
@@ -0,0 +1,15 @@
+
+class whatever {
+};
+
+class whatever_child: public whatever {
+};
+
+class whatever_child_with_member: public whatever {
+public:
+    int m_member;
+};
+
+static_assert(sizeof(whatever) == 1, "Testing!");
+static_assert(sizeof(whatever_child) == 1, "Testing!");
+static_assert(sizeof(whatever_child_with_member) == 4, "Testing!");