Fix infinite recursion caused by aliased resources.

This commit fixes an existing bug exposed by the refactoring (likely due to the
changes in the order in which nodes are processed for implicit arguments).

Previously, an interface might contain a type alias for another resource it
owns; this lead to the alias information of the resource being self-referential
for the interface containing the aliased resource.

It would then lead to infinite recursion in an attempt to remap such an
interface when populating implicit instantiation arguments.

The fix is to clear the self-referencing information while converting an
interface during package parsing.

Author: peterhuene

crates/wac-parser/tests/encoding/include-resource.wac

@@ -0,0 +1,3 @@
+package test:comp;
+
+let x = new foo:bar { ... };

crates/wac-parser/tests/encoding/include-resource.wac.result

@@ -0,0 +1,51 @@
+(component
+  (type (;0;)
+    (instance
+      (export (;0;) "fields" (type (sub resource)))
+      (export (;1;) "headers" (type (eq 0)))
+    )
+  )
+  (import "test:comp/types" (instance (;0;) (type 0)))
+  (alias export 0 "fields" (type (;1;)))
+  (type (;2;)
+    (instance
+      (alias outer 1 1 (type (;0;)))
+      (export (;1;) "headers" (type (eq 0)))
+      (type (;2;) (own 1))
+      (type (;3;) (func (result 2)))
+      (export (;0;) "get-headers" (func (type 3)))
+    )
+  )
+  (import "test:comp/incoming-request" (instance (;1;) (type 2)))
+  (type (;3;)
+    (component
+      (type (;0;)
+        (instance
+          (export (;0;) "fields" (type (sub resource)))
+          (export (;1;) "headers" (type (eq 0)))
+        )
+      )
+      (import "test:comp/types" (instance (;0;) (type 0)))
+      (alias export 0 "fields" (type (;1;)))
+      (type (;2;)
+        (instance
+          (alias outer 1 1 (type (;0;)))
+          (export (;1;) "headers" (type (eq 0)))
+          (type (;2;) (own 1))
+          (type (;3;) (func (result 2)))
+          (export (;0;) "get-headers" (func (type 3)))
+        )
+      )
+      (import "test:comp/incoming-request" (instance (;1;) (type 2)))
+    )
+  )
+  (import "unlocked-dep=<foo:bar>" (component (;0;) (type 3)))
+  (instance $x (;2;) (instantiate 0
+      (with "test:comp/types" (instance 0))
+      (with "test:comp/incoming-request" (instance 1))
+    )
+  )
+  (@producers
+    (processed-by "wac-parser" "0.1.0")
+  )
+)

crates/wac-parser/tests/encoding/include-resource/foo/bar.wat

@@ -0,0 +1,56 @@
+(component
+  (type (;0;)
+    (instance
+      (export (;0;) "fields" (type (sub resource)))
+      (export (;1;) "headers" (type (eq 0)))
+    )
+  )
+  (import "test:comp/types" (instance (;0;) (type 0)))
+  (alias export 0 "headers" (type (;1;)))
+  (type (;2;)
+    (instance
+      (alias outer 1 1 (type (;0;)))
+      (export (;1;) "headers" (type (eq 0)))
+      (type (;2;) (own 1))
+      (type (;3;) (func (result 2)))
+      (export (;0;) "get-headers" (func (type 3)))
+    )
+  )
+  (import "test:comp/incoming-request" (instance (;1;) (type 2)))
+  (core module (;0;)
+    (type (;0;) (func (param i32)))
+    (type (;1;) (func (result i32)))
+    (type (;2;) (func (param i32 i32 i32 i32) (result i32)))
+    (import "test:comp/types" "[resource-drop]fields" (func (;0;) (type 0)))
+    (import "test:comp/incoming-request" "get-headers" (func (;1;) (type 1)))
+    (func (;2;) (type 2) (param i32 i32 i32 i32) (result i32)
+      unreachable
+    )
+    (memory (;0;) 0)
+    (export "memory" (memory 0))
+    (export "cabi_realloc" (func 2))
+    (@producers
+      (processed-by "wit-component" "0.203.0")
+    )
+  )
+  (alias export 0 "fields" (type (;3;)))
+  (core func (;0;) (canon resource.drop 3))
+  (core instance (;0;)
+    (export "[resource-drop]fields" (func 0))
+  )
+  (alias export 1 "get-headers" (func (;0;)))
+  (core func (;1;) (canon lower (func 0)))
+  (core instance (;1;)
+    (export "get-headers" (func 1))
+  )
+  (core instance (;2;) (instantiate 0
+      (with "test:comp/types" (instance 0))
+      (with "test:comp/incoming-request" (instance 1))
+    )
+  )
+  (alias core export 2 "memory" (core memory (;0;)))
+  (alias core export 2 "cabi_realloc" (core func (;2;)))
+  (@producers
+    (processed-by "wit-component" "0.203.0")
+  )
+)

crates/wac-types/src/component.rs

@@ -789,9 +789,9 @@ impl fmt::Display for FuncKind {
 #[cfg_attr(feature = "serde", derive(serde::Serialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
 pub struct ResourceAlias {
-    /// The owning interface for the resource.
+    /// The foreign owning interface for the resource.
     ///
-    /// This may be `None` if the resource is owned by a world.
+    /// This may be `None` if the resource does not have a foreign interface owner.
     #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none"))]
     pub owner: Option<InterfaceId>,
     /// The id of the resource that was aliased.

crates/wac-types/src/package.rs

@@ -551,6 +551,17 @@ impl<'a> TypeConverter<'a> {
             } = ty
             {
                 self.use_or_own(Owner::Interface(id), name, *referenced, *created);
+
+                // Prevent self-referential ownership of any aliased resources in this interface
+                if let ItemKind::Type(Type::Resource(res)) = export {
+                    if let Some(ResourceAlias { owner, .. }) = &mut self.types[res].alias {
+                        if let Some(owner_id) = owner {
+                            if *owner_id == id {
+                                *owner = None;
+                            }
+                        }
+                    }
+                }
             }
 
             let prev = self.types[id].exports.insert(name.clone(), export);