Add filename to the BadFile exception (#858)

The BadFile exception which is thrown when failing to open a file now
contains the filename.

include/yaml-cpp/exceptions.h

@@ -136,7 +136,7 @@ inline const std::string INVALID_NODE_WITH_KEY(const std::string& key) {
   stream << "invalid node; first invalid key: \"" << key << "\"";
   return stream.str();
 }
-}
+}  // namespace ErrorMsg
 
 class YAML_CPP_API Exception : public std::runtime_error {
  public:
@@ -249,8 +249,7 @@ class YAML_CPP_API BadSubscript : public RepresentationException {
  public:
   template <typename Key>
   BadSubscript(const Mark& mark_, const Key& key)
-      : RepresentationException(mark_,
-                                ErrorMsg::BAD_SUBSCRIPT_WITH_KEY(key)) {}
+      : RepresentationException(mark_, ErrorMsg::BAD_SUBSCRIPT_WITH_KEY(key)) {}
   BadSubscript(const BadSubscript&) = default;
   ~BadSubscript() YAML_CPP_NOEXCEPT override;
 };
@@ -281,10 +280,12 @@ class YAML_CPP_API EmitterException : public Exception {
 
 class YAML_CPP_API BadFile : public Exception {
  public:
-  BadFile() : Exception(Mark::null_mark(), ErrorMsg::BAD_FILE) {}
+  explicit BadFile(const std::string& filename)
+      : Exception(Mark::null_mark(),
+                  std::string(ErrorMsg::BAD_FILE) + ": " + filename) {}
   BadFile(const BadFile&) = default;
   ~BadFile() YAML_CPP_NOEXCEPT override;
 };
-}
+}  // namespace YAML
 
 #endif  // EXCEPTIONS_H_62B23520_7C8E_11DE_8A39_0800200C9A66

src/parse.cpp

@@ -30,9 +30,9 @@ Node Load(std::istream& input) {
 }
 
 Node LoadFile(const std::string& filename) {
-  std::ifstream fin(filename.c_str());
+  std::ifstream fin(filename);
   if (!fin) {
-    throw BadFile();
+    throw BadFile(filename);
   }
   return Load(fin);
 }
@@ -63,9 +63,9 @@ std::vector<Node> LoadAll(std::istream& input) {
 }
 
 std::vector<Node> LoadAllFromFile(const std::string& filename) {
-  std::ifstream fin(filename.c_str());
+  std::ifstream fin(filename);
   if (!fin) {
-    throw BadFile();
+    throw BadFile(filename);
   }
   return LoadAll(fin);
 }