From 6f4cf3ebecdd720ed31c0257543fd071f41afc17 Mon Sep 17 00:00:00 2001
From: Marius Kintel <marius@kintel.net>
Date: Mon, 10 Feb 2014 02:19:56 -0500
Subject: [PATCH] Fixed a bug failing to detect changes in underlying
 libraries. Should improve some of the issues reported in #181

---
 src/ModuleCache.cc | 17 +++++++++++------
 src/ModuleCache.h  |  2 +-
 src/module.cc      | 23 +++++++++++++----------
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/src/ModuleCache.cc b/src/ModuleCache.cc
index 595a4631..d79a0261 100644
--- a/src/ModuleCache.cc
+++ b/src/ModuleCache.cc
@@ -22,12 +22,16 @@
 ModuleCache *ModuleCache::inst = NULL;
 
 /*!
-	Reevaluate the given file and recompile if necessary.
-	Returns NULL on any error (e.g. compile error or file not found)
-
+	Reevaluate the given file and all it's dependencies and recompile anything
+	needing reevaluation.
 	The given filename must be absolute.
+
+	Sets the module reference to the new modile, or NULL on any error (e.g. compile
+	error or file not found)
+
+	Returns true if anything was compiled (module or dependencies) and false otherwise.
 */
-FileModule *ModuleCache::evaluate(const std::string &filename)
+bool ModuleCache::evaluate(const std::string &filename, FileModule *&module)
 {
 	FileModule *lib_mod = NULL;
 	bool found = false;
@@ -115,9 +119,10 @@ FileModule *ModuleCache::evaluate(const std::string &filename)
 		print_messages_pop();
 	}
 	
-	if (lib_mod) lib_mod->handleDependencies();
+	module = lib_mod;
+	bool depschanged = lib_mod ? lib_mod->handleDependencies() : false;
 
-	return lib_mod;
+	return shouldCompile || depschanged;
 }
 
 void ModuleCache::clear()
diff --git a/src/ModuleCache.h b/src/ModuleCache.h
index e8a45807..0c15fbda 100644
--- a/src/ModuleCache.h
+++ b/src/ModuleCache.h
@@ -8,7 +8,7 @@ class ModuleCache
 {
 public:
 	static ModuleCache *instance() { if (!inst) inst = new ModuleCache; return inst; }
-	class FileModule *evaluate(const std::string &filename);
+	bool evaluate(const std::string &filename, class FileModule *&module);
 	class FileModule *lookup(const std::string &filename);
 	bool isCached(const std::string &filename);
 	size_t size() { return this->entries.size(); }
diff --git a/src/module.cc b/src/module.cc
index dc89a6f6..ccc475e4 100644
--- a/src/module.cc
+++ b/src/module.cc
@@ -263,8 +263,8 @@ bool FileModule::handleDependencies()
 	if (this->is_handling_dependencies) return false;
 	this->is_handling_dependencies = true;
 
-	bool changed = false;
-	std::vector<std::string> updates;
+	bool somethingchanged = false;
+	std::vector<std::pair<std::string,std::string> > updates;
 
 	// If a lib in usedlibs was previously missing, we need to relocate it
 	// by searching the applicable paths. We can identify a previously missing module
@@ -279,9 +279,8 @@ bool FileModule::handleDependencies()
 			wasmissing = true;
 			fs::path fullpath = find_valid_path(this->path, filename);
 			if (!fullpath.empty()) {
+				updates.push_back(std::make_pair(filename, boosty::stringy(fullpath)));
 				filename = boosty::stringy(fullpath);
-				updates.push_back(filename);
-				this->usedlibs.erase(filename);
 			}
 			else {
 				found = false;
@@ -291,15 +290,16 @@ bool FileModule::handleDependencies()
 		if (found) {
 			bool wascached = ModuleCache::instance()->isCached(filename);
 			FileModule *oldmodule = ModuleCache::instance()->lookup(filename);
-			FileModule *newmodule = ModuleCache::instance()->evaluate(filename);
+			FileModule *newmodule;
+			bool changed = ModuleCache::instance()->evaluate(filename, newmodule);
 			// Detect appearance but not removal of files, and keep old module
 			// on compile errors (FIXME: Is this correct behavior?)
-			if (newmodule && oldmodule != newmodule) {
-				changed = true;
+			if (changed) {
 #ifdef DEBUG
 				PRINTB_NOCACHE("  %s: %p -> %p", filename % oldmodule % newmodule);
 #endif
 			}
+			somethingchanged |= changed;
 			// Only print warning if we're not part of an automatic reload
 			if (!newmodule && !wascached && !wasmissing) {
 				PRINTB_NOCACHE("WARNING: Failed to compile library '%s'.", filename);
@@ -308,10 +308,13 @@ bool FileModule::handleDependencies()
 	}
 
 	// Relative filenames which were located is reinserted as absolute filenames
-	BOOST_FOREACH(const std::string &filename, updates) this->usedlibs.insert(filename);
-
+	typedef std::pair<std::string,std::string> stringpair;
+	BOOST_FOREACH(const stringpair &files, updates) {
+		this->usedlibs.erase(files.first);
+		this->usedlibs.insert(files.second);
+	}
 	this->is_handling_dependencies = false;
-	return changed;
+	return somethingchanged;
 }
 
 AbstractNode *FileModule::instantiate(const Context *ctx, const ModuleInstantiation *inst, const EvalContext *evalctx) const