1 files changed, 64 insertions, 0 deletions
diff --git a/layout/base/LayoutLogging.h b/layout/base/LayoutLogging.h
new file mode 100644
index 0000000000..72335ff3eb
--- /dev/null
+++ b/layout/base/LayoutLogging.h
@@ -0,0 +1,64 @@
+/* -*- 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/. */
+
+#ifndef LayoutLogging_h
+#define LayoutLogging_h
+
+#include "mozilla/Logging.h"
+
+/**
+ * Retrieves the log module to use for layout logging.
+ */
+static mozilla::LazyLogModule sLayoutLog("layout");
+
+/**
+ * Use the layout log to warn if a given condition is false.
+ *
+ * This is only enabled in debug builds and the logging is only displayed if
+ * the environmental variable MOZ_LOG includes "layout:2" (or higher).
+ */
+#ifdef DEBUG
+#  define LAYOUT_WARN_IF_FALSE(_cond, _msg)                                 \
+    PR_BEGIN_MACRO                                                          \
+    if (MOZ_LOG_TEST(sLayoutLog, mozilla::LogLevel::Warning) && !(_cond)) { \
+      mozilla::detail::LayoutLogWarning(_msg, #_cond, __FILE__, __LINE__);  \
+    }                                                                       \
+    PR_END_MACRO
+#else
+#  define LAYOUT_WARN_IF_FALSE(_cond, _msg) \
+    PR_BEGIN_MACRO                          \
+    PR_END_MACRO
+#endif
+
+/**
+ * Use the layout log to emit a warning with the same format as NS_WARNING.
+ *
+ * This is only enabled in debug builds and the logging is only displayed if
+ * the environmental variable MOZ_LOG includes "layout:2" (or higher).
+ */
+#ifdef DEBUG
+#  define LAYOUT_WARNING(_msg)                                              \
+    PR_BEGIN_MACRO                                                          \
+    if (MOZ_LOG_TEST(sLayoutLog, mozilla::LogLevel::Warning)) {             \
+      mozilla::detail::LayoutLogWarning(_msg, nullptr, __FILE__, __LINE__); \
+    }                                                                       \
+    PR_END_MACRO
+#else
+#  define LAYOUT_WARNING(_msg) \
+    PR_BEGIN_MACRO             \
+    PR_END_MACRO
+#endif
+
+namespace mozilla {
+namespace detail {
+
+void LayoutLogWarning(const char* aStr, const char* aExpr, const char* aFile,
+                      int32_t aLine);
+
+}  // namespace detail
+}  // namespace mozilla
+
+#endif  // LayoutLogging_h