From ebc752bac6019b45f330877e0f828d79cf2a4f73 Mon Sep 17 00:00:00 2001
From: Ryan Levick <ryan.levick@fermyon.com>
Date: Mon, 15 Apr 2024 15:43:15 +0200
Subject: [PATCH] Loosen restriction on top-level resource alias imports.

Previously, we assumed that all resource aliases had some owning
interface, but that might not be the case. Users can alias resources at
the world level. This lifts two restrictions that erroneously encoded
this incorrect assumption.

Fixes https://github.com/bytecodealliance/wac/issues/81
---
 crates/wac-graph/src/encoding.rs              |  1 -
 .../graphs/import-resource-alias/encoded.wat  | 25 +++++++++++++++++++
 .../graphs/import-resource-alias/graph.json   | 14 +++++++++++
 .../graphs/import-resource-alias/world.wit    |  7 ++++++
 crates/wac-types/src/package.rs               |  7 ++----
 5 files changed, 48 insertions(+), 6 deletions(-)
 create mode 100644 crates/wac-graph/tests/graphs/import-resource-alias/encoded.wat
 create mode 100644 crates/wac-graph/tests/graphs/import-resource-alias/graph.json
 create mode 100644 crates/wac-graph/tests/graphs/import-resource-alias/world.wit

diff --git a/crates/wac-graph/src/encoding.rs b/crates/wac-graph/src/encoding.rs
index 3efd2a2..8e8d58c 100644
--- a/crates/wac-graph/src/encoding.rs
+++ b/crates/wac-graph/src/encoding.rs
@@ -577,7 +577,6 @@ impl<'a> TypeEncoder<'a> {
     }
 
     fn own(&self, state: &mut State, res: ResourceId) -> u32 {
-        assert!(!state.scopes.is_empty());
         let res = state.current.resources[self.0[res].name.as_str()];
         let index = state.current.encodable.type_count();
         state.current.encodable.ty().defined_type().own(res);
diff --git a/crates/wac-graph/tests/graphs/import-resource-alias/encoded.wat b/crates/wac-graph/tests/graphs/import-resource-alias/encoded.wat
new file mode 100644
index 0000000..2cf8734
--- /dev/null
+++ b/crates/wac-graph/tests/graphs/import-resource-alias/encoded.wat
@@ -0,0 +1,25 @@
+(component
+  (import "x" (type (;0;) (sub resource)))
+  (import "y" (type (;1;) (eq 0)))
+  (type (;2;) (own 0))
+  (type (;3;) (own 1))
+  (type (;4;) (func (param "x" 2) (result 3)))
+  (import "f" (func (;0;) (type 4)))
+  (type (;5;)
+    (component
+      (import "x" (type (;0;) (sub resource)))
+      (import "y" (type (;1;) (eq 0)))
+      (type (;2;) (own 0))
+      (type (;3;) (own 1))
+      (type (;4;) (func (param "x" 2) (result 3)))
+      (import "f" (func (;0;) (type 4)))
+    )
+  )
+  (import "unlocked-dep=<test:foo>" (component (;0;) (type 5)))
+  (instance (;0;) (instantiate 0
+      (with "x" (type 0))
+      (with "y" (type 1))
+      (with "f" (func 0))
+    )
+  )
+)
diff --git a/crates/wac-graph/tests/graphs/import-resource-alias/graph.json b/crates/wac-graph/tests/graphs/import-resource-alias/graph.json
new file mode 100644
index 0000000..6413c42
--- /dev/null
+++ b/crates/wac-graph/tests/graphs/import-resource-alias/graph.json
@@ -0,0 +1,14 @@
+{
+    "packages": [
+        {
+            "name": "test:foo",
+            "path": "world.wit"
+        }
+    ],
+    "nodes": [
+        {
+            "type": "instantiation",
+            "package": 0
+        }
+    ]
+}
\ No newline at end of file
diff --git a/crates/wac-graph/tests/graphs/import-resource-alias/world.wit b/crates/wac-graph/tests/graphs/import-resource-alias/world.wit
new file mode 100644
index 0000000..5748535
--- /dev/null
+++ b/crates/wac-graph/tests/graphs/import-resource-alias/world.wit
@@ -0,0 +1,7 @@
+package example:foo;
+
+world w {
+  resource x;
+  type y = x;
+  import f: func(x: x) -> y;
+}
\ No newline at end of file
diff --git a/crates/wac-types/src/package.rs b/crates/wac-types/src/package.rs
index 8811fea..b4ce2dd 100644
--- a/crates/wac-types/src/package.rs
+++ b/crates/wac-types/src/package.rs
@@ -765,11 +765,8 @@ impl<'a> TypeConverter<'a> {
             let alias_id = self.types.add_resource(Resource {
                 name: name.to_owned(),
                 alias: Some(ResourceAlias {
-                    owner: match self
-                        .find_owner(ComponentAnyTypeId::Resource(id))
-                        .expect("should have owner")
-                    {
-                        (Owner::Interface(id), _) => Some(*id),
+                    owner: match self.find_owner(ComponentAnyTypeId::Resource(id)) {
+                        Some((Owner::Interface(id), _)) => Some(*id),
                         _ => None,
                     },
                     source: *resource_id,