Fix crash due to i2d out-of-bounds access

By controlling the order of static object construction
through the "Construct on First Use" idiom.

src/filedetails.cpp

@@ -57,7 +57,16 @@
 #include "md5.h"
 #include "os.h"
 
-FI_id_to_details Filedetails::i2d;	// From id to file details
+/*
+ * Return the map from file id to file details, controlling the order of its
+ * construction through the "Construct on First Use" idiom.
+ */
+FI_id_to_details &
+Filedetails::get_i2d()
+{
+	static FI_id_to_details i2d;
+	return i2d;
+}
 
 /*
  * Return a map of files that are exact duplicates, controlling the order
@@ -185,7 +194,7 @@ Filedetails::set_hand_edited()
 void
 Filedetails::clear_all_visited()
 {
-	for (FI_id_to_details::iterator i = i2d.begin(); i != i2d.end(); i++)
+	for (FI_id_to_details::iterator i = get_i2d().begin(); i != get_i2d().end(); i++)
 		i->clear_visited();
 }
 

src/filedetails.h

@@ -107,7 +107,9 @@ class Filedetails {
 	string contents;	// Original contents, if hand-edited
 	bool visited;                   // For calculating transitive closures
 
-	static FI_id_to_details i2d;	// From id to file details
+	// Get map from id to file details
+	static FI_id_to_details& get_i2d();
+
 	// Return map of files that are exact duplicates
 	static FI_hash_to_ids& get_identical_files();
 public:
@@ -121,16 +123,16 @@ class Filedetails {
 
 	// Return the instance associated with the specified id
 	static Filedetails &get_instance(Fileid fi) {
-		return i2d[fi.get_id()];
+		return get_i2d()[fi.get_id()];
 	}
 
 	static FI_id_to_details::size_type get_i2d_map_size() {
-		return i2d.size();
+		return get_i2d().size();
 	}
 
 	// Add a new instance with the specified ctor values
 	static void add_instance(string n, bool r, const FileHash &hash) {
-		i2d.emplace_back(n, r, hash);
+		get_i2d().emplace_back(n, r, hash);
 	}
 
 	// Unify identifiers of files that are exact copies