Handle pointer constness at the right level.

Author: emilio

src/codegen/mod.rs

@@ -3054,7 +3054,7 @@ impl TryToRustTy for Type {
             }
             TypeKind::Pointer(inner) |
             TypeKind::Reference(inner) => {
-                let is_const = self.is_const() || ctx.resolve_type(inner).is_const();
+                let is_const = ctx.resolve_type(inner).is_const();
 
                 let inner = inner.into_resolver().through_type_refs().resolve(ctx);
                 let inner_ty = inner.expect_type();

src/ir/ty.rs

@@ -1195,22 +1195,7 @@ impl Type {
 
         let name = if name.is_empty() { None } else { Some(name) };
 
-        // Just using ty.is_const() is wrong here, because when we declare an
-        // argument like 'int* const arg0', arg0 is considered
-        // const but the pointer itself points to mutable data.
-        //
-        // Without canonicalizing the type to the pointer type, we'll get the
-        // following mapping:
-        //
-        // arg0: *const c_int
-        //
-        // So by canonicalizing the type first, we can check constness by
-        // calling is_const() on the pointer type.
-        let is_const = if let Some(pty) = ty.pointee_type() {
-            pty.is_const()
-        } else {
-            ty.is_const()
-        };
+        let is_const = ty.is_const();
 
         let ty = Type::new(name, layout, kind, is_const);
         // TODO: maybe declaration.canonical()?