[Clang][Windows] Options.cpp(317,25): error: no matching function for call to 'optionTypeSpecificIndex'
https://bugs.webkit.org/show_bug.cgi?id=203142

Unreviewed build fix

clang-cl reported a compilation error for MSVC bug workaround code of optionTypeSpecificIndex.

runtime\Options.cpp(294,12): error: variables defined in a constexpr function must be initialized
    size_t index;
           ^
* runtime/Options.cpp:
(JSC::optionTypeSpecificIndex): Initialize the variable 'index'.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@251276 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
index 867de01..53116e2 100644
--- a/Source/JavaScriptCore/ChangeLog
+++ b/Source/JavaScriptCore/ChangeLog
@@ -1,3 +1,18 @@
+2019-10-18  Fujii Hironori  <Hironori.Fujii@sony.com>
+
+        [Clang][Windows] Options.cpp(317,25): error: no matching function for call to 'optionTypeSpecificIndex'
+        https://bugs.webkit.org/show_bug.cgi?id=203142
+
+        Unreviewed build fix
+
+        clang-cl reported a compilation error for MSVC bug workaround code of optionTypeSpecificIndex.
+
+        runtime\Options.cpp(294,12): error: variables defined in a constexpr function must be initialized
+            size_t index;
+                   ^
+        * runtime/Options.cpp:
+        (JSC::optionTypeSpecificIndex): Initialize the variable 'index'.
+
 2019-10-17  Mark Lam  <mark.lam@apple.com>
 
         Add missing checks after calls to the sameValue() JSValue comparator.
diff --git a/Source/JavaScriptCore/runtime/Options.cpp b/Source/JavaScriptCore/runtime/Options.cpp
index 29bf1dd..dce021f5 100644
--- a/Source/JavaScriptCore/runtime/Options.cpp
+++ b/Source/JavaScriptCore/runtime/Options.cpp
@@ -291,7 +291,7 @@
 template<OptionTypeID type, OptionID id>
 constexpr size_t optionTypeSpecificIndex()
 {
-    size_t index;
+    size_t index = 0;
     index = 0; // MSVC (16.3.5) improperly optimizes away the inline initialization of index, so use an explicit assignment.
 
 #define COUNT_INDEX_AND_FIND_MATCH(type_, name_, defaultValue_, availability_, description_) \