Handle error cases during module script tree fetching/running better

As discussed in #1545 and in https://esdiscuss.org/topic/moduledeclarationinstantiation-behaviour-after-failure, the spec would potentially call ModuleDeclarationInstantiation on a module that previously failed to instantiate, with cascading bad consequences for the rest of the spec's algorithms. The JavaScript spec expects us to track these failures and avoid calling ModuleDeclarationInstantiation a second time. This commit adds such state tracking, partially by moving the ModuleDeclarationInstantiation calls to fetch time (with any errors stored for later rethrowing during evaluation time). Fixes #1545.
whatwg · Aug 1, 2016 · 9ed4c2c · 9ed4c2c
1 parent d0f0d6c
commit 9ed4c2c
Showing 1 changed file with 113 additions and 23 deletions.
diff --git a/source b/source
@@ -85871,6 +85871,27 @@ interface <dfn>NavigatorOnLine</dfn> {
 
    </dd>
 
+   <dt>An <dfn data-x="concept-module-script-instantiation-state">instantiation state</dfn></dt>
+
+   <dd>
+
+    <p>One of "<code data-x="">uninstantiated</code>", "<code data-x="">errored</code>", or "<code
+    data-x="">instantiated</code>", used to prevent reinvocation of <span
+    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span> on modules that
+    failed to instantiate previously.</p>
+
+   </dd>
+
+   <dt>An <dfn data-x="concept-module-script-instantiation-error">instantiation error</dfn></dt>
+
+   <dd>
+
+    <p>A JavaScript value, which has meaning only if the <span
+    data-x="concept-module-script-instantiation-state">instantiation state</span> is "<code
+    data-x="">errored</code>".</p>
+
+   </dd>
+
    <dt>A <dfn data-x="concept-module-script-credentials-mode">credentials mode</dfn></dt>
 
    <dd>
@@ -86300,11 +86321,74 @@ interface <dfn>NavigatorOnLine</dfn> {
    <li><p>Otherwise, <var>result</var> is a <span>module script</span>. <span data-x="fetch the
    descendants of a module script">Fetch the descendants</span> of <var>result</var> given
    <var>destination</var> and an ancestor list obtained by appending <var>url</var> to <var>ancestor
-   list</var>.</p></li>
+   list</var>. Wait for <span data-x="fetch the descendants of a module script">fetching the
+   descendants of a module script</span> to asynchronously complete with <var>descendants
+   result</var> before proceeding to the next step.</p></li>
+
+   <li><p>Let <var>record</var> be <var>result</var>'s <span
+   data-x="concept-module-script-module-record">module record</span>.</p>
+
+   <li>
+    <p>Let <var>instantiationStatus</var> be <var>record</var>.<span
+    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span>().</p>
+
+    <p class="note">This step will recursively call <span
+    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span> all of the
+    module's dependencies.</p>
+   </li>
+
+   <li>
+    <p>For each <span>module script</span> <var>script</var> in <var>result</var>'s
+    <span>uninstantiated inclusive descendant module scripts</span>, perform the following
+    steps:</p>
+
+    <ol>
+     <li><p>If <var>instantiationStatus</var> is an abrupt completion, set <var>script</var>'s
+     <span data-x="concept-module-script-instantiation-state">instantiation state</span> to "<code
+     data-x="">errored</code>", its <span
+     data-x="concept-module-script-instantiation-error">instantiation error</span> to
+     <var>instantiationStatus</var>.[[Value]], and its <span
+     data-x="concept-module-script-module-record">module record</span> to null.</p></li>
+
+     <li><p>Otherwise, set <var>script</var>'s <span
+     data-x="concept-module-script-instantiation-state">instantiation state</span> to "<code
+     data-x="">instantiated</code>".</p></li>
+    </ol>
+   </li>
 
-   <li><p>When <span data-x="fetch the descendants of a module script">fetching the descendants of
-   a module script</span> asynchronously completes with <var>descendants result</var>,
-   asynchronously complete this algorithm with <var>descendants result</var>.</p></li>
+   <li>
+    <p>Asynchronously complete this algorithm with <var>descendants result</var>.</p>
+
+    <p class="note">It is intentional that we complete with <var>descendants result</var> here, and
+    not <var>result</var>, as this allows us to propagate error signals to the caller.</p>
+   </li>
+  </ol>
+
+  <p>In the above algorithm, a <span>module script</span> <var>script</var>'s <dfn>uninstantiated
+  inclusive descendant module scripts</dfn> is a list of <span data-x="module script">module
+  scripts</span> determined as follows:</p>
+
+  <ol>
+   <li><p>Let <var>module map</var> be <var>script</var>'s <span>settings object</span>'s
+   <span>module map</span>.</p></li>
+
+   <li><p>Let <var>descendant specifiers</var> be the value of <var>script</var>'s <span
+   data-x="concept-module-script-module-record">module record</span>'s [[RequestedModules]] internal
+   slot.</p></li>
+
+   <li><p>Let <var>descendant URLs</var> be the list obtained by applying <span>resolve a module
+   specifier</span> to each element of <var>descendant specifiers</var>, omitting any
+   failures.</p></li>
+
+   <li><p>Let <var>descendant modules</var> be the list obtained by looking up each value in
+   <var>module map</var> whose key is given by an element of <var>descendant URLs</var>.</p></li>
+
+   <li><p>Let <var>inclusive descendants</var> be the list obtained by appending <var>script</var>
+   to <var>descendant modules</var>.</p></li>
+
+   <li><p>Return a list containing all elements of <var>inclusive descendants</var> whose <span
+   data-x="concept-module-script-instantiation-state">instantiation state</span> is "<code
+   data-x="">uninstantiated</code>".</p></li>
   </ol>
 
   <p>To <dfn>fetch a single module script</dfn>, given a <var>url</var>, a <var>fetch client
@@ -86454,14 +86538,10 @@ interface <dfn>NavigatorOnLine</dfn> {
     <span data-x="fetching-scripts-perform-fetch">perform the fetch</span> steps, pass those along
     while performing the <span>internal module script tree fetching procedure</span>.</p>
 
-    <p>If any of the <span>internal module script tree fetching procedure</span> invocations
-    asynchronously complete with null, the user agent may <span
-    data-x="concept-fetch-terminate">terminate</span> any or all of the other fetches, and must then
-    asynchronously complete this algorithm with null.</p>
-
-    <p>Once all of the <span>internal module script tree fetching procedure</span> invocations
-    asynchronously complete with a <span>module script</span>, asynchronously complete this
-    algorithm with <var>module script</var>.</p>
+    <p>Wait for all of the <span>internal module script tree fetching procedure</span> invocations
+    to asynchronously complete. If any of them asynchronously complete with null, asynchronously
+    complete this algorithm with null. Otherwise, asynchronously complete this algorithm with
+    <var>module script</var>.</p>
    </li>
   </ol>
 
@@ -86611,19 +86691,19 @@ interface <dfn>NavigatorOnLine</dfn> {
    <li><p><span>Check if we can run script</span> with <var>settings</var>. If this returns "do
    not run" then abort these steps.</p></li>
 
-   <li><p>Let <var>record</var> be <var>s</var>'s <span
-   data-x="concept-module-script-module-record">module record</span>.</p>
+   <li><p>If <var>s</var>'s <span data-x="concept-module-script-instantiation-state">instantiation
+   state</span> is "<code data-x="">errored</code>", <span>report the
+   exception</span> given by <var>s</var>'s <span
+   data-x="concept-module-script-instantiation-error">instantiation error</span> for <var>s</var>
+   and abort these steps.</p></li>
 
-   <li>
-    <p>Let <var>instantiationStatus</var> be <var>record</var>.<span
-    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span>().</p>
+   <li><p>Assert: <var>s</var>'s <span
+   data-x="concept-module-script-instantiation-state">instantiation state</span> is "<code
+   data-x="">instantiated</code>" (and thus its <span
+   data-x="concept-module-script-module-record">module record</span> is not null).</p></li>
 
-    <p class="note">This step will recursively instantiate all of the module's dependencies.</p>
-   </li>
-
-   <li><p>If <var>instantiationStatus</var> is an abrupt completion, <span>report the
-   exception</span> given by <var>instantiationStatus</var>.[[Value]] for <var>s</var> and abort
-   these steps.</p></li>
+   <li><p>Let <var>record</var> be <var>s</var>'s <span
+   data-x="concept-module-script-module-record">module record</span>.</p>
 
    <li><p><span>Prepare to run script</span> given <var>settings</var>.</p></li>
 
@@ -87421,6 +87501,16 @@ document.querySelector("button").addEventListener("click", bound);
    data-x="">fetching</code>", throw a <code>TypeError</code> exception and abort these
    steps.</p></li>
 
+   <li><p>If <var>resolved module script</var>'s <span
+   data-x="concept-module-script-instantiation-state">instantiation state</span> is "<code
+   data-x="">errored</code>", throw <var>resolved module script</var>'s <span
+   data-x="concept-module-script-instantiation-error">instantiation error</span>.</p></li>
+
+   <li><p>Assert: <var>resolved module script</var>'s <span
+   data-x="concept-module-script-instantiation-state">instantiation state</span> is "<code
+   data-x="">instantiated</code>" (and thus its <span
+   data-x="concept-module-script-module-record">module record</span> is not null).</p></li>
+
    <li><p>Return <var>resolved module script</var>'s <span
    data-x="concept-module-script-module-record">module record</span>.</p></li>
   </ol>