Auto merge of #823 - fitzgen:issue-820-unused-template-param-in-alias, r=emilio

Implement `IsOpaque` for `CompInfo`

This allows us to properly detect structs that should be treated as opaque due to their non-type template paramaters, which in turn lets us correctly codegen template aliases to such things.

Fixes #820

r? @emilio

Author: bors-servo

src/ir/comp.rs

@@ -1422,6 +1422,14 @@ impl DotAttributes for CompInfo {
     }
 }
 
+impl IsOpaque for CompInfo {
+    type Extra = ();
+
+    fn is_opaque(&self, _: &BindgenContext, _: &()) -> bool {
+        self.has_non_type_template_params
+    }
+}
+
 impl TemplateParameters for CompInfo {
     fn self_template_params(&self,
                             _ctx: &BindgenContext)
@@ -1442,7 +1450,7 @@ impl CanDeriveDebug for CompInfo {
                         layout: Option<Layout>)
                         -> bool {
         if self.has_non_type_template_params() {
-            return layout.map_or(false, |l| l.opaque().can_derive_debug(ctx, ()));
+            return layout.map_or(true, |l| l.opaque().can_derive_debug(ctx, ()));
         }
 
         // We can reach here recursively via template parameters of a member,
@@ -1498,9 +1506,11 @@ impl CanDeriveDefault for CompInfo {
                 return false;
             }
 
-            return layout.unwrap_or_else(Layout::zero)
-                .opaque()
-                .can_derive_default(ctx, ());
+            return layout.map_or(true, |l| l.opaque().can_derive_default(ctx, ()));
+        }
+
+        if self.has_non_type_template_params {
+            return layout.map_or(true, |l| l.opaque().can_derive_default(ctx, ()));
         }
 
         self.detect_derive_default_cycle.set(true);
@@ -1528,7 +1538,7 @@ impl<'a> CanDeriveCopy<'a> for CompInfo {
                        (item, layout): (&Item, Option<Layout>))
                        -> bool {
         if self.has_non_type_template_params() {
-            return layout.map_or(false, |l| l.opaque().can_derive_copy(ctx, ()));
+            return layout.map_or(true, |l| l.opaque().can_derive_copy(ctx, ()));
         }
 
         // NOTE: Take into account that while unions in C and C++ are copied by

src/ir/template.rs

@@ -361,14 +361,23 @@ impl CanDeriveDebug for TemplateInstantiation {
                         layout: Option<Layout>)
                         -> bool {
         self.args.iter().all(|arg| arg.can_derive_debug(ctx, ())) &&
-        ctx.resolve_type(self.definition)
+        self.definition
+            .into_resolver()
+            .through_type_refs()
+            .through_type_aliases()
+            .resolve(ctx)
+            .as_type()
+            .expect("Instantiation of a non-type?")
             .as_comp()
             .and_then(|c| {
                 // For non-type template parameters, we generate an opaque
                 // blob, and in this case the instantiation has a better
                 // idea of the layout than the definition does.
                 if c.has_non_type_template_params() {
-                    let opaque = layout.unwrap_or(Layout::zero()).opaque();
+                    let opaque = layout
+                        .or_else(|| ctx.resolve_type(self.definition).layout(ctx))
+                        .unwrap_or(Layout::zero())
+                        .opaque();
                     Some(opaque.can_derive_debug(ctx, ()))
                 } else {
                     None

src/ir/ty.rs

@@ -358,6 +358,7 @@ impl IsOpaque for Type {
         match self.kind {
             TypeKind::Opaque => true,
             TypeKind::TemplateInstantiation(ref inst) => inst.is_opaque(ctx, item),
+            TypeKind::Comp(ref comp) => comp.is_opaque(ctx, &()),
             _ => false,
         }
     }
@@ -562,6 +563,9 @@ impl CanDeriveDebug for Type {
             TypeKind::TemplateInstantiation(ref inst) => {
                 inst.can_derive_debug(ctx, self.layout(ctx))
             }
+            TypeKind::Opaque => {
+                self.layout.map_or(true, |l| l.opaque().can_derive_debug(ctx, ()))
+            }
             _ => true,
         }
     }

tests/expectations/tests/issue-372.rs

@@ -83,6 +83,7 @@ pub mod root {
         ai = 11,
     }
     #[repr(C)]
+    #[derive(Copy)]
     pub struct F {
         pub w: [u64; 33usize],
     }
@@ -98,6 +99,9 @@ pub mod root {
                     "Alignment of field: " , stringify ! ( F ) , "::" ,
                     stringify ! ( w ) ));
     }
+    impl Clone for F {
+        fn clone(&self) -> Self { *self }
+    }
     impl Default for F {
         fn default() -> Self { unsafe { ::std::mem::zeroed() } }
     }

tests/expectations/tests/issue-569-non-type-template-params-causing-layout-test-failures.rs

@@ -11,13 +11,15 @@ pub const ENUM_VARIANT_2: _bindgen_ty_1 = _bindgen_ty_1::ENUM_VARIANT_2;
 pub enum _bindgen_ty_1 { ENUM_VARIANT_1 = 0, ENUM_VARIANT_2 = 1, }
 pub type JS_Alias = u8;
 #[repr(C)]
+#[derive(Debug, Copy, Clone)]
 pub struct JS_Base {
     pub f: JS_Alias,
 }
 impl Default for JS_Base {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }
 #[repr(C)]
+#[derive(Debug, Copy)]
 pub struct JS_AutoIdVector {
     pub _base: JS_Base,
 }
@@ -28,6 +30,9 @@ fn bindgen_test_layout_JS_AutoIdVector() {
     assert_eq! (::std::mem::align_of::<JS_AutoIdVector>() , 1usize , concat !
                 ( "Alignment of " , stringify ! ( JS_AutoIdVector ) ));
 }
+impl Clone for JS_AutoIdVector {
+    fn clone(&self) -> Self { *self }
+}
 impl Default for JS_AutoIdVector {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }

tests/expectations/tests/issue-573-layout-test-failures.rs

@@ -5,11 +5,15 @@
 
 
 #[repr(C)]
-#[derive(Default)]
+#[derive(Debug, Copy, Clone)]
 pub struct Outer {
     pub i: u8,
 }
+impl Default for Outer {
+    fn default() -> Self { unsafe { ::std::mem::zeroed() } }
+}
 #[repr(C)]
+#[derive(Debug, Copy)]
 pub struct AutoIdVector {
     pub ar: Outer,
 }
@@ -25,6 +29,9 @@ fn bindgen_test_layout_AutoIdVector() {
                 "Alignment of field: " , stringify ! ( AutoIdVector ) , "::" ,
                 stringify ! ( ar ) ));
 }
+impl Clone for AutoIdVector {
+    fn clone(&self) -> Self { *self }
+}
 impl Default for AutoIdVector {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }

tests/expectations/tests/issue-820-unused-template-param-in-alias.rs

@@ -0,0 +1,7 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+
+pub type Foo_self_type = u8;

tests/expectations/tests/non-type-params.rs

@@ -7,6 +7,7 @@
 pub type Array16 = u8;
 pub type ArrayInt4 = [u32; 4usize];
 #[repr(C)]
+#[derive(Debug, Copy)]
 pub struct UsesArray {
     pub array_char_16: [u8; 16usize],
     pub array_bool_8: [u8; 8usize],
@@ -34,6 +35,9 @@ fn bindgen_test_layout_UsesArray() {
                 "Alignment of field: " , stringify ! ( UsesArray ) , "::" ,
                 stringify ! ( array_int_4 ) ));
 }
+impl Clone for UsesArray {
+    fn clone(&self) -> Self { *self }
+}
 impl Default for UsesArray {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }

tests/expectations/tests/size_t_template.rs

@@ -5,6 +5,7 @@
 
 
 #[repr(C)]
+#[derive(Debug, Copy)]
 pub struct C {
     pub arr: [u32; 3usize],
 }
@@ -20,6 +21,9 @@ fn bindgen_test_layout_C() {
                 "Alignment of field: " , stringify ! ( C ) , "::" , stringify
                 ! ( arr ) ));
 }
+impl Clone for C {
+    fn clone(&self) -> Self { *self }
+}
 impl Default for C {
     fn default() -> Self { unsafe { ::std::mem::zeroed() } }
 }

tests/headers/issue-820-unused-template-param-in-alias.hpp

@@ -0,0 +1,5 @@
+template<typename E, int N>
+class Foo {
+    typedef Foo<E, N> self_type;
+    E mBar;
+};