[PATCH] Fix --type-id-style hash for empty internal names.

[Giuliano Procida]

libabigail's intern_string class treats the empty string specially. It
is not safe to call the raw method without checking for a empty
pointer. It is safe to convert to std::string.

This commit changes the XML writer to convert interned strings to
std::strings before computing their hashes.

	* src/abg-writer.cc (write_context::get_id_for_type): When
	hashing internal type names, convert to std::string rather
	than using the raw method directly as this will avoid a null
	pointer dereference in the case of an empty string; tabify
	code indentation.

Signed-off-by: Giuliano Procida <gprocida@google.com>
---
 src/abg-writer.cc | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/abg-writer.cc b/src/abg-writer.cc
index ce0bae2d..b9813ef4 100644
--- a/src/abg-writer.cc
+++ b/src/abg-writer.cc
@@ -450,20 +450,21 @@ public:
     switch (m_type_id_style)
       {
       case SEQUENCE_TYPE_ID_STYLE:
-        {
-          interned_string id = get_id_manager().get_id_with_prefix("type-id-");
-          return m_type_id_map[c] = id;
-        }
+	{
+	  interned_string id = get_id_manager().get_id_with_prefix("type-id-");
+	  return m_type_id_map[c] = id;
+	}
       case HASH_TYPE_ID_STYLE:
-        {
-          interned_string pretty = c->get_cached_pretty_representation(true);
-          size_t hash = hashing::fnv_hash(*pretty.raw());
-          while (!m_used_type_id_hashes.insert(hash).second)
-            ++hash;
-          std::ostringstream os;
-          os << std::hex << std::setfill('0') << std::setw(8) << hash;
-          return m_type_id_map[c] = c->get_environment()->intern(os.str());
-        }
+	{
+	  interned_string pretty = c->get_cached_pretty_representation(true);
+	  std::string str = pretty;
+	  size_t hash = hashing::fnv_hash(str);
+	  while (!m_used_type_id_hashes.insert(hash).second)
+	    ++hash;
+	  std::ostringstream os;
+	  os << std::hex << std::setfill('0') << std::setw(8) << hash;
+	  return m_type_id_map[c] = c->get_environment()->intern(os.str());
+	}
       }
     ABG_ASSERT_NOT_REACHED;
     return interned_string();
-- 
2.27.0.212.ge8ba1cc988-goog