From de7ca0d3ce73bfa3f870c4257dbf71e621224876 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 18 Jul 2012 18:32:47 +0300
Subject: [PATCH] Fix cascading of BuildInfo

---
 source/buildinfo.cpp |  2 +-
 source/buildinfo.h   | 40 +++++++++++++++++++++++++++++++++-------
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/source/buildinfo.cpp b/source/buildinfo.cpp
index b7f9c5c..c02d115 100644
--- a/source/buildinfo.cpp
+++ b/source/buildinfo.cpp
@@ -100,7 +100,7 @@ void BuildInfo::Loader::library(const string &s)
 }
 
 
-void operator>>(LexicalConverter &conv, BuildInfo::LibraryMode &libmode)
+void operator>>(const LexicalConverter &conv, BuildInfo::LibraryMode &libmode)
 {
 	if(conv.get()=="FORCE_STATIC")
 		libmode = BuildInfo::FORCE_STATIC;
diff --git a/source/buildinfo.h b/source/buildinfo.h
index ca8819d..e0929e7 100644
--- a/source/buildinfo.h
+++ b/source/buildinfo.h
@@ -39,6 +39,32 @@ public:
 		CHAINED      //< Include only compilation options
 	};
 
+	/**
+	A wrapper which tracks the set status of the wrapped variable.  A default
+	value may be provided in initialization without causing it to be treated as
+	set.  Assigning from a raw value flags the Tracked object as set.  Assigning
+	from another Tracked object will only change the value of the target if the
+	source is set.  
+	*/
+	template<typename T>
+	class Tracked
+	{
+	public:
+		typedef T LoadType;
+
+	private:
+		T value;
+		bool set;
+
+	public:
+		Tracked(): value(T()), set(false) { }
+		Tracked(T v): value(v), set(false) { }
+		Tracked &operator=(const Tracked &v) { if(v.set) { value = v.value; set = true; } return *this; }
+
+		Tracked &operator=(T v) { value = v; set = true; return *this; }
+		operator T() const { return value; }
+	};
+
 	typedef std::map<std::string, std::string> DefineMap;
 	typedef std::list<Msp::FS::Path> PathList;
 	typedef std::list<std::string> WordList;
@@ -47,13 +73,13 @@ public:
 	PathList incpath;
 	PathList libpath;
 	WordList libs;
-	LibraryMode libmode;
-	bool threads;
-	bool debug;
-	int optimize;
-	bool strip;
-	unsigned warning_level;
-	bool fatal_warnings;
+	Tracked<LibraryMode> libmode;
+	Tracked<bool> threads;
+	Tracked<bool> debug;
+	Tracked<int> optimize;
+	Tracked<bool> strip;
+	Tracked<unsigned> warning_level;
+	Tracked<bool> fatal_warnings;
 
 	BuildInfo();
 
-- 
2.45.2