From e86cdc4020bad2015e0b5bd8e7b9b683b9661035 Mon Sep 17 00:00:00 2001
From: Richard Heck <rgheck@lyx.org>
Date: Wed, 5 Mar 2014 18:45:42 -0500
Subject: [PATCH] Fix bug #8999 by locking math macros while they are updating.

---
 src/mathed/MathMacro.cpp | 18 ++++++++++++++++++
 src/mathed/MathMacro.h   |  4 ++++
 2 files changed, 22 insertions(+)

diff --git a/src/mathed/MathMacro.cpp b/src/mathed/MathMacro.cpp
index 2f0241b5ac..e536af5372 100644
--- a/src/mathed/MathMacro.cpp
+++ b/src/mathed/MathMacro.cpp
@@ -312,9 +312,27 @@ void MathMacro::updateMacro(MacroContext const & mc)
 }
 
 
+class MathMacro::UpdateLocker
+{
+public:
+	explicit UpdateLocker(MathMacro & mm) : mac(mm)
+	{
+		mac.isUpdating_ = true;
+	}
+	~UpdateLocker() { mac.isUpdating_ = false; }
+private:
+	MathMacro & mac;
+};
+
+
 void MathMacro::updateRepresentation(Cursor * cur, MacroContext const & mc,
 		UpdateType utype)
 {
+	if (isUpdating_)
+		return;
+
+	UpdateLocker(*this);
+
 	// known macro?
 	if (macro_ == 0)
 		return;
diff --git a/src/mathed/MathMacro.h b/src/mathed/MathMacro.h
index b7308562ff..b2d75534d2 100644
--- a/src/mathed/MathMacro.h
+++ b/src/mathed/MathMacro.h
@@ -183,6 +183,10 @@ private:
 	std::string requires_;
 	/// update macro representation
 	bool needsUpdate_;
+	/// update lock to avoid loops
+	class UpdateLocker;
+	friend class UpdateLocker;
+	bool isUpdating_;
 	/// maximal number of arguments the macro is greedy for
 	size_t appetite_;
 
-- 
2.39.2