simplify: remove cyclic binding handling

Author: guybedford

document/js-api/index.bs

@@ -123,6 +123,7 @@ urlPrefix: https://webassembly.github.io/spec/core/; spec: WebAssembly; type: df
     text: store_init; url: appendix/embedding.html#embed-store-init
     text: module_decode; url: appendix/embedding.html#embed-module-decode
     text: module_validate; url: appendix/embedding.html#embed-module-validate
+    text: module_extern_subtype; url: appendix/embedding.html#embed-module-extern-subtype
     text: module_instantiate; url: appendix/embedding.html#embed-module-instantiate
     text: module_imports; url: appendix/embedding.html#embed-module-imports
     text: module_exports; url: appendix/embedding.html#embed-module-exports
@@ -156,6 +157,7 @@ urlPrefix: https://webassembly.github.io/spec/core/; spec: WebAssembly; type: df
     text: memory address; url: exec/runtime.html#syntax-memaddr
     text: global address; url: exec/runtime.html#syntax-globaladdr
     text: extern address; url: exec/runtime.html#syntax-externaddr
+    text: extern subtype; url: valid/types.html#match-externtype
     text: page size; url: exec/runtime.html#page-size
     url: syntax/types.html#syntax-numtype
         text: i32
@@ -1163,7 +1165,7 @@ Note: Exported Functions do not have a \[[Construct]] method and thus it is not
         1. Let |values| be [=?=] [$IteratorToList$]([=?=] [$GetIteratorFromMethod$](|ret|, |method|)).
         1. Let |wasmValues| be a new, empty [=list=].
         1. If |values|'s [=list/size=] is not |resultsSize|, throw a {{TypeError}} exception.
-        1. [=list/iterate|For each=] |value| and |resultType| in |values| and |results|, paired linearly,
+        1. For each |value| and |resultType| in |values| and |results|, paired linearly,
             1. [=list/Append=] [=ToWebAssemblyValue=](|value|, |resultType|) to |wasmValues|.
         1. Return |wasmValues|.
 </div>
@@ -1388,9 +1390,11 @@ To <dfn export>parse a WebAssembly module</dfn> given a <a>byte sequence</a> |by
 1. If |module| is [=error=], throw a {{CompileError}} exception.
 1. [=Construct a WebAssembly module object=] from |module| and |bytes|, and let |module| be the result.
 1. Let |requestedModules| be a set.
-1. [=list/iterate|For each=] (|moduleName|, <var ignore>name</var>, <var ignore>type</var>) in [=module_imports=](|module|.\[[Module]]),
+1. For each (|moduleName|, <var ignore>name</var>, <var ignore>type</var>) in [=module_imports=](|module|.\[[Module]]),
     1. [=set/Append=] |moduleName| to |requestedModules|.
 1. Let |moduleRecord| be {
+      <!-- WebAssembly Module Records -->
+      \[[Instance]]: ~empty~,
       <!-- Abstract Module Records -->
       \[[Realm]]: |realm|,
       \[[Environment]]: ~empty~,
@@ -1422,7 +1426,7 @@ The <dfn>export name list</dfn> of a WebAssembly Module Record |record| is defin
 
 1. Let |module| be |record|'s \[[ModuleSource]] internal slot.
 1. Let |exports| be an empty [=list=].
-1. [=list/iterate|For each=] (|name|, <var ignore>type</var>) in [=module_exports=](|module|.\[[Module]])
+1. For each (|name|, <var ignore>type</var>) in [=module_exports=](|module|.\[[Module]])
     1. [=list/Append=] |name| to the end of |exports|.
 1. Return |exports|.
 
@@ -1483,9 +1487,9 @@ WebAssembly Module Records have the following methods:
         1. Let |resolutionName| be |resolution|.\[[BindingName]].
         1. Let |externval| be [=instance_export=](|resolutionInstance|, |resolutionName|).
         1. Assert: |externval| is not [=error=].
-        1. Assert: [=module_direct_exports=](|resolutionModule|) contains an element (|resolutionName|, <var ignore>type</var>).
-        1. Let |externtype| be the value of |type| for the element (|resolutionName|, |type|) in [=module_direct_exports=](|resolutionModule|).
-        1. If [=module_extern_subtype=](|externtype|, |importtype|) is false, throw a {{LinkError}} exception.
+        1. Assert: [=module_exports=](|resolutionModule|) contains an element (|resolutionName|, <var ignore>type</var>).
+        1. Let |externtype| be the value of |type| for the element (|resolutionName|, |type|) in [=module_exports=](|resolutionModule|).
+        1. If |importtype| is not an [=extern subtype=] of |externtype|, throw a {{LinkError}} exception.
         1. [=list/Append=] |externval| to |imports|.
     1. Otherwise,
         1. Let |env| be |resolution|.\[[Module]].\[[Environment]].
@@ -1500,13 +1504,15 @@ WebAssembly Module Records have the following methods:
             1. Let |externfunc| be the [=external value=] [=external value|func=] |funcaddr|.
             1. [=list/Append=] |externfunc| to |imports|.
         1. If |importtype| is of the form [=global=] |mut| |valtype|,
+            1. Let |store| be the [=surrounding agent=]'s [=associated store=].
             1. If |v| [=implements=] {{Global}},
                 1. Let |globaladdr| be |v|.\[[Global]].
+                1. Let |targetmut| <var ignore>valuetype</var> be [=global_type=](|store|, |globaladdr|).
+                    1. If |mut| is [=const=] and |targetmut| is [=var=], throw a {{TypeError}}.
             1. Otherwise,
-                1. If |valtype| is [=v128=],
-                    1. Throw a {{LinkError}} exception.
+                1. If |valtype| is [=v128=], throw a {{LinkError}} exception.
+                1. If |mut| is [=var=], throw a {{TypeError}}.
                 1. Let |value| be [=?=] [=ToWebAssemblyValue=](|v|, |valtype|).
-                1. Let |store| be the [=surrounding agent=]'s [=associated store=].
                 1. Let (|store|, |globaladdr|) be [=global_alloc=](|store|, |mut| |valtype|, |value|).
                 1. Set the [=surrounding agent=]'s [=associated store=] to |store|.
             1. Let |externglobal| be [=external value|global=] |globaladdr|.
@@ -1522,53 +1528,34 @@ WebAssembly Module Records have the following methods:
             1. [=list/Append=] |externtable| to |imports|.
 1. [=Instantiate the core of a WebAssembly module=] |module| with |imports|, and let |instance| be the result.
 1. Set |record|.\[[Instance]] to |instance|.
-1. [=list/iterate|For each=] (|name|, |externtype|) of [=module_direct_exports=](|module|),
-    1. Let |externval| be [=instance_export=](|instance|, |name|).
-    1. Assert: |externval| is not [=error=].
-    1. If |externtype| is of the form [=func=] <var ignore>functype</var>,
-        1. Assert: |externval| is of the form [=external value|func=] |funcaddr|.
-        1. Let [=external value|func=] |funcaddr| be |externval|.
-        1. Let |func| be the result of creating [=a new Exported Function=] from |funcaddr|.
-        1. Perform [=!=] |record|.\[[Environment]].InitializeBinding(|name|, |func|).
+1. [=list/iterate|For each=] (|name|, |externtype|) of [=module_exports=](|module|),
     1. If |externtype| is of the form [=global=] |mut| |globaltype|,
         1. Assert: |externval| is of the form [=external value|global=] |globaladdr|.
         1. Let [=external value|global=] |globaladdr| be |externval|.
         1. Let |global_value| be [=global_read=](|store|, |globaladdr|).
         1. If |globaltype| is not [=v128=],
-            1. Note: When integrating with shared globals, they will be excluded here similarly to v128 above.
+            1. Note: The condition above leaves unsupported JS values as uninitialized in TDZ and therefore as a reference error on
+                access. When integrating with shared globals, they may be excluded here similarly to v128 above. 
             1. Perform [=!=] |record|.\[[Environment]].InitializeBinding(|name|, [=ToJSValue=](|global_value|)).
-            1. Associate all future mutations to the mutable value at |globaladdr| with the ECMA-262 binding record for |name| in
+            1. If |mut| is [=var=], then associate all future mutations of |globaladdr| with the ECMA-262 binding record for |name| in
                 |record|.\[[Environment]], such that |record|.\[[Environment]].GetBindingValue(|resolution|.\[[BindingName]], true)
                 always returns [=ToJSValue=]([=global_read=](|store|, |globaladdr|)) for the current [=surrounding agent=]'s
                 [=associated store=] |store|.
-    1. If |externtype| is of the form [=mem=] <var ignore>memtype</var>,
-        1. Assert: |externval| is of the form [=external value|mem=] |memaddr|.
-        1. Let [=external value|mem=] |memaddr| be |externval|.
-        1. Let |memory| be [=create a memory object|a new Memory object=] created from |memaddr|.
-        1. Perform [=!=] |record|.\[[Environment]].InitializeBinding(|name|, |memory|).
-    1. If |externtype| is of the form [=table=] <var ignore>tabletype</var>,
-        1. Assert: |externval| is of the form [=external value|table=] |tableaddr|.
-        1. Let [=external value|table=] |tableaddr| be |externval|.
-        1. Let |table| be [=create a Table object|a new Table object=] created from |tableaddr|.
-        1. Perform [=!=] |record|.\[[Environment]].InitializeBinding(|name|, |table|).
-
-Note: The export bindings for a WebAssembly Module Record are designed to mirror the live bindings of all directly exported values. Values not
-supported in JS are left uninitialized and in TDZ, while still being accesible to Wasm importers. Indirect exports (re-exports) referencing
-JavaScript values will capture the [=ToWebAssemblyValue=] interpretation at the time of execution, while indirect exports resolving to other Wasm
-modules will support Wasm live bindings. For exported mutable globals that are supported in JavaScript, the live bindings on the environment record
-will always reflect the current mutable global export value as interpreted through the infallible [=ToJSValue=] interpretation.
+    1. Otherwise,
+        1. Perform ! |record|.\[[Environment]].InitializeBinding(|name|, ! Get(|instance|.\[[Exports]], |name|)).
 
 </div>
 
 <h3 id="hostgetmodulesourcemodulerecord">HostGetModuleSourceModuleRecord ( |specifier| )</h3>
 1. If |specifier| is a WebAssembly {{Module}} object with a \[[Module]] internal slot,
-    1. Let |module| be |specifier|.\[[Module]].
-    1. If |module|.\[[ModuleRecord]] is null,
+    1. If |specifier|.\[[Module]].\[[ModuleRecord]] is null,
         1. Let |realm| be the current agent's realm record.
         1. Let |requestedModules| be a set.
-        1. [=list/iterate|For each=] (|moduleName|, <var ignore>name</var>, <var ignore>type</var>) in [=module_imports=](|module|),
+        1. For each (|moduleName|, <var ignore>name</var>, <var ignore>type</var>) in [=module_imports=](|specifier|.\[[Module]]),
             1. [=set/Append=] |moduleName| to |requestedModules|.
         1. Let |moduleRecord| be {
+              <!-- WebAssembly Module Records -->
+              \[[Instance]]: ~empty~,
               <!-- Abstract Module Records -->
               \[[Realm]]: |realm|,
               \[[Environment]]: ~empty~,
@@ -1591,7 +1578,7 @@ will always reflect the current mutable global export value as interpreted throu
             }.
         1. Set |module|.\[[ModuleRecord]] to |moduleRecord|.
         1. Return |moduleRecord|.
-    1. Return |module|.\[[ModuleRecord]].
+    1. Return |specifier|.\[[Module]].\[[ModuleRecord]].
 1. Return ~not-a-source~.
 
 Note: See corresponding modifications to HTML in <a href="https://github.com/whatwg/html/pull/10380">PR #10380</a>.

proposals/esm-integration/EXAMPLES.md

@@ -123,13 +123,17 @@ for (let index = 0; index < length; index++)
 | table       | `WebAssembly.Table` object  |
 | function    | WebAssembly exported function |
 
+Wasm bindings cannot be reassigned as it can in JS, so the exported value will not change in their object identity. But the value that it points to (e.g. `.value` in the case of `WebAssembly.Global`) can change.
+
 1. JS module is parsed
 1. wasm module is parsed
 1. wasm module has a lexical environment created for its exports. All exports are initially in TDZ.
 1. JS module is instantiated. Imports are bound to the same memory locations.
 1. wasm module is instantiated evaluated. Functions are initialized. Memories and tables are initialized and filled with data/elem sections. Globals are initialized and initializer expressions are evaluated. The start function runs.
 1. JS module is evaluated. All values are available.
 
+The value of the export for `WebAssembly.Global` is provided directly on the JS namespace object, with mutable globals reflected as live bindings to JS.
+
 #### Example
 
 ```js
@@ -177,7 +181,7 @@ Wasm exports can be imported as accurate, immutable bindings to other wasm modul
 
 ### wasm imports <- JS re-exports <- wasm exports
 
-Any wasm exports that are re-exported via a JS module will be available to the other wasm module as accurate bindings. If the binding is a mutable global, then that binding will be a live export binding in JS reflecting changes to the Wasm global value. When imported from JS, the first and second Wasm modules will yield the same Wasm identities for the multiply exported Wasm objects.
+Any wasm exports that are re-exported via a JS module will be available to the other wasm module as accurate, immutable bindings. The wasm export gets wrapped into a JS object (e.g. `WebAssembly.Global`) and then unwrapped to the wasm import in the importing wasm module. When imported from JS, the first and second Wasm modules will yield the same object identities for the multiply exported Wasm objects.
 
 #### Example
 
@@ -213,7 +217,7 @@ export {memoryExport} from "./b.wasm";
 
 1. JS module is parsed
 1. wasm module is parsed
-1. wasm module has a lexical environment created for its exports. All direct exports are initially in TDZ, indirect exports are available as they resolve.
+1. wasm module has a lexical environment created for its exports. All exports are initially in TDZ.
 1. JS module is instantiated. All imports (including functions) from the wasm module are memory locations holding undefined.
 1. wasm module is instantiated and evaluated. Snapshots of imports are taken. Export bindings are initialized.
 1. JS module is evaluated. 
@@ -251,8 +255,8 @@ export function functionExport() {
 1. wasm module is parsed
 1. JS module is parsed
 1. JS module is instantiated. 
-1. wasm module has a lexical environment created for its exports. All direct exports are initially in TDZ, indirect exports are available as they resolve.
-1. JS module is evaluated. wasm exports in TDZ lead to a ReferenceError if used.
+1. wasm module has a lexical environment created for its exports. All exports are initially in TDZ.
+1. JS module is evaluated. wasm exports lead to a ReferenceError if used.
 1. wasm module is instantiated and evaluated; wasm-exported bindings are updated to their appropriate JS API-exposed values. 
 
 #### Examples