SourceLocation: Fix use-after-move.

third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp

Index: third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp b/third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp
index f7e4197f4b94008753555589c481ea87de5ecacc..c806cf2a0ab609b14bf1862d1a30a82c0134ecea 100644
--- a/third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/SourceLocation.cpp
@@ -41,8 +41,10 @@ std::unique_ptr<V8StackTrace> captureStackTrace()
 PassOwnPtr<SourceLocation> SourceLocation::capture(const String& url, unsigned lineNumber, unsigned columnNumber)
 {
     std::unique_ptr<V8StackTrace> stackTrace = captureStackTrace();
-    if (stackTrace && !stackTrace->isEmpty())
-        return SourceLocation::create(stackTrace->topSourceURL(), stackTrace->topLineNumber(), stackTrace->topColumnNumber(), std::move(stackTrace), 0);
+    if (stackTrace && !stackTrace->isEmpty()) {
+        const V8StackTrace* stackTracePtr = stackTrace.get();

[Yuki, 2016/05/26 06:55:50]

I'm a bit uneasy to use a raw pointer here.
    const String& url = stackTrace->topSourceURL();
    const unsigned lineNumber = stackTrace->topLineNumber();
    ...
    return SourceLocation::create(url, lineNumber, ...);
seems more "right things" to me, personally.

Anyway, without a comment, it's not easy to understand the intention.  I'd
propose the following things in the preferred order.

1) Adds SourceLocation::create(std::unique_ptr<V8StackTrace>, int scriptId = 0)
and use it.  No need to pass url, line number, etc. seeing these two cases.
2) Adds a comment to explain the fix.  Why it's needed.
2-1) [optional] Use temporary variables rather than a raw pointer.

It's fine to assign the issue to me if you don't have time.

[kinaba, 2016/05/26 07:14:19]

Makes sense. Done.

+        return SourceLocation::create(stackTracePtr->topSourceURL(), stackTracePtr->topLineNumber(), stackTracePtr->topColumnNumber(), std::move(stackTrace), 0);
+    }
     return SourceLocation::create(url, lineNumber, columnNumber, std::move(stackTrace));
 }
 
@@ -50,8 +52,10 @@ PassOwnPtr<SourceLocation> SourceLocation::capture(const String& url, unsigned l
 PassOwnPtr<SourceLocation> SourceLocation::capture(ExecutionContext* executionContext)
 {
     std::unique_ptr<V8StackTrace> stackTrace = captureStackTrace();
-    if (stackTrace && !stackTrace->isEmpty())
-        return SourceLocation::create(stackTrace->topSourceURL(), stackTrace->topLineNumber(), stackTrace->topColumnNumber(), std::move(stackTrace), 0);
+    if (stackTrace && !stackTrace->isEmpty()) {
+        const V8StackTrace* stackTracePtr = stackTrace.get();
+        return SourceLocation::create(stackTracePtr->topSourceURL(), stackTracePtr->topLineNumber(), stackTracePtr->topColumnNumber(), std::move(stackTrace), 0);
+    }
 
     Document* document = executionContext && executionContext->isDocument() ? toDocument(executionContext) : nullptr;
     if (document) {