From 5fe8c4e5449568387f659b7708f44faf3d3bb4a5 Mon Sep 17 00:00:00 2001
From: Jeff Muizelaar <jmuizelaar@mozilla.com>
Date: Tue, 1 Dec 2015 20:43:17 -0500
Subject: [PATCH] Bug 1228641. Add a polyfill of std::initializer_list.
 r=froydnj

---
 config/stl-headers                 |  1 +
 config/system-headers              |  1 +
 mfbt/InitializerList.h             | 62 ++++++++++++++++++++++++++++++
 mfbt/moz.build                     |  1 +
 mfbt/tests/TestInitializerList.cpp | 24 ++++++++++++
 mfbt/tests/moz.build               |  1 +
 testing/cppunittest.ini            |  1 +
 7 files changed, 91 insertions(+)
 create mode 100644 mfbt/InitializerList.h
 create mode 100644 mfbt/tests/TestInitializerList.cpp

diff --git a/config/stl-headers b/config/stl-headers
index a1f77ac5ba6..1e4922df664 100644
--- a/config/stl-headers
+++ b/config/stl-headers
@@ -20,6 +20,7 @@ new
 algorithm
 atomic
 deque
+initializer_list
 ios
 iosfwd
 iostream
diff --git a/config/system-headers b/config/system-headers
index cde1cad17b8..b2b7d9c2ba0 100644
--- a/config/system-headers
+++ b/config/system-headers
@@ -548,6 +548,7 @@ image.h
 imagehlp.h
 imm.h
 initguid.h
+initializer_list
 InterfaceDefs.h
 InternetConfig.h
 IntlResources.h
diff --git a/mfbt/InitializerList.h b/mfbt/InitializerList.h
new file mode 100644
index 00000000000..0f324253275
--- /dev/null
+++ b/mfbt/InitializerList.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ *  * License, v. 2.0. If a copy of the MPL was not distributed with this
+ *   * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A polyfill for std::initializer_list if it doesn't exist */
+
+#ifndef mozilla_InitializerList_h
+#define mozilla_InitializerList_h
+
+#include <mozilla/Compiler.h>
+#include <mozilla/Attributes.h>
+#if MOZ_USING_LIBCXX
+#  define MOZ_HAVE_INITIALIZER_LIST
+#elif MOZ_USING_LIBSTDCXX && __GLIBCXX__ >= 20090421 // GCC 4.4.0
+#  define MOZ_HAVE_INITIALIZER_LIST
+#elif _MSC_VER
+#  define MOZ_HAVE_INITIALIZER_LIST
+#elif defined(MOZ_USING_STLPORT)
+#else
+#  error "Unknown standard library situation"
+#endif
+
+#ifdef MOZ_HAVE_INITIALIZER_LIST
+#  include <initializer_list>
+#else
+/* Normally we would put things in mozilla:: however, std::initializer_list is a
+ * magic name used by the compiler and so we need to name it that way.
+ */
+namespace std
+{
+
+template<class T>
+class initializer_list
+{
+    /* This matches the representation used by GCC and Clang which
+     * are the only compilers we need to polyfill */
+    const T* mBegin;
+    size_t   mSize;
+
+    /* This constructor is called directly by the compiler */
+    initializer_list(const T* begin, size_t size) : mBegin(begin), mSize(size) {}
+public:
+
+    MOZ_CONSTEXPR initializer_list() : mBegin(nullptr), mSize(0) {}
+
+    typedef T value_type;
+    typedef const T& reference;
+    typedef const T& const_reference;
+    typedef size_t size_type;
+    typedef const T* iterator;
+    typedef const T* const_iterator;
+
+    size_t size() const { return mSize; }
+    const T* begin() const { return mBegin; }
+    const T* end() const { return mBegin + mSize; }
+};
+
+}
+#endif /* MOZ_HAS_INITIALIZER_LIST */
+#endif /* mozilla_InitializerList_h */
diff --git a/mfbt/moz.build b/mfbt/moz.build
index 67c276df3d6..4eefdf9e29c 100644
--- a/mfbt/moz.build
+++ b/mfbt/moz.build
@@ -44,6 +44,7 @@ EXPORTS.mozilla = [
     'GuardObjects.h',
     'HashFunctions.h',
     'IndexSequence.h',
+    'InitializerList.h',
     'IntegerPrintfMacros.h',
     'IntegerRange.h',
     'IntegerTypeTraits.h',
diff --git a/mfbt/tests/TestInitializerList.cpp b/mfbt/tests/TestInitializerList.cpp
new file mode 100644
index 00000000000..03bc60bca45
--- /dev/null
+++ b/mfbt/tests/TestInitializerList.cpp
@@ -0,0 +1,24 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/InitializerList.h"
+
+int sum(std::initializer_list<int> p)
+{
+  int result = 0;
+  for (auto i : p) {
+    result += i;
+  }
+  return result;
+}
+
+int
+main()
+{
+  MOZ_RELEASE_ASSERT(sum({1, 2, 3, 4, 5, 6}) == 7 * 3);
+  return 0;
+}
diff --git a/mfbt/tests/moz.build b/mfbt/tests/moz.build
index 850254b57e0..c75ee8eec15 100644
--- a/mfbt/tests/moz.build
+++ b/mfbt/tests/moz.build
@@ -19,6 +19,7 @@ CppUnitTests([
     'TestFastBernoulliTrial',
     'TestFloatingPoint',
     'TestFunction',
+    'TestInitializerList',
     'TestIntegerPrintfMacros',
     'TestIntegerRange',
     'TestJSONWriter',
diff --git a/testing/cppunittest.ini b/testing/cppunittest.ini
index 57b967c17de..05899358c4b 100644
--- a/testing/cppunittest.ini
+++ b/testing/cppunittest.ini
@@ -38,6 +38,7 @@ skip-if = os != 'win'
 [TestGetURL]
 [TestHashtables]
 [TestID]
+[TestInitializerList]
 [TestIntegerPrintfMacros]
 [TestIntegerRange]
 [TestJSONWriter]