1367204 - Generate "[sourceless code]" for class constructors when sourceIsLazy and no source hook is set.

1 files changed, 14 insertions, 5 deletions

diff --git a/js/src/jsfun.cpp b/js/src/jsfun.cpp
index 06dc40162..9edf238ef 100644
--- a/js/src/jsfun.cpp
+++ b/js/src/jsfun.cpp
@@ -1013,7 +1013,20 @@ js::FunctionToString(JSContext* cx, HandleFunction fun, bool prettyPrint)
             if (!out.append(")"))
                 return nullptr;
         }
-    } else if (fun->isInterpreted() && !fun->isSelfHostedBuiltin()) {
+    } else if (fun->isInterpreted() &&
+               (!fun->isSelfHostedBuiltin() ||
+                fun->infallibleIsDefaultClassConstructor(cx)))
+    {
+        // Default class constructors should always haveSource except;
+        //
+        // 1. Source has been discarded for the whole compartment.
+        //
+        // 2. The source is marked as "lazy", i.e., retrieved on demand, and
+        // the embedding has not provided a hook to retrieve sources.
+        MOZ_ASSERT_IF(fun->infallibleIsDefaultClassConstructor(cx),
+                      !cx->runtime()->sourceHook ||
+                      !script->scriptSource()->sourceRetrievable() ||
+                      fun->compartment()->behaviors().discardSource());
         if (!AppendPrelude() ||
             !out.append("() {\n    ") ||
             !out.append("[sourceless code]") ||
@@ -1022,10 +1035,6 @@ js::FunctionToString(JSContext* cx, HandleFunction fun, bool prettyPrint)
             return nullptr;
         }
     } else {
-        // Default class constructors should always haveSource unless source
-        // has been discarded for the whole compartment.
-        MOZ_ASSERT(!fun->infallibleIsDefaultClassConstructor(cx) ||
-                   fun->compartment()->behaviors().discardSource());
 
         if (!AppendPrelude() ||
             !out.append("() {\n    "))