Issue #2259 - Add mozilla::Result<V, E> and JS::Result<> for fallible return values

Based-on: m-c 1283562, 1277368/1, 1324828

1 files changed, 35 insertions, 0 deletions

diff --git a/js/src/jscntxt.cpp b/js/src/jscntxt.cpp
index dc14b83fd9..66a548d6e8 100644
--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -240,6 +240,13 @@ js::ReportOutOfMemory(ExclusiveContext* cxArg)
     cx->setPendingException(oomMessage, nullptr);
 }
 
+mozilla::GenericErrorResult<OOM&>
+js::ReportOutOfMemoryResult(ExclusiveContext* cx)
+{
+    ReportOutOfMemory(cx);
+    return cx->alreadyReportedOOM();
+}
+
 void
 js::ReportOverRecursed(JSContext* maybecx, unsigned errorNumber)
 {
@@ -1004,6 +1011,34 @@ ExclusiveContext::recoverFromOutOfMemory()
         task->outOfMemory = false;
 }
 
+JS::Error ExclusiveContext::reportedError;
+JS::OOM ExclusiveContext::reportedOOM;
+
+mozilla::GenericErrorResult<OOM&>
+ExclusiveContext::alreadyReportedOOM()
+{
+#ifdef DEBUG
+    if (JSContext* maybecx = maybeJSContext()) {
+        MOZ_ASSERT(maybecx->isThrowingOutOfMemory());
+    } else {
+        // Keep in sync with addPendingOutOfMemory.
+        if (ParseTask* task = helperThread()->parseTask())
+            MOZ_ASSERT(task->outOfMemory);
+    }
+#endif
+    return mozilla::MakeGenericErrorResult(reportedOOM);
+}
+
+mozilla::GenericErrorResult<JS::Error&>
+ExclusiveContext::alreadyReportedError()
+{
+#ifdef DEBUG
+    if (JSContext* maybecx = maybeJSContext())
+        MOZ_ASSERT(maybecx->isExceptionPending());
+#endif
+    return mozilla::MakeGenericErrorResult(reportedError);
+}
+
 JSContext::JSContext(JSRuntime* parentRuntime)
   : ExclusiveContext(this, &this->JSRuntime::mainThread, Context_JS, JS::ContextOptions()),
     JSRuntime(parentRuntime),