Make bcache more type-safe

The bcache uses memcpy to make copies of the data passed to it.  In
C++, this is only safe for trivially-copyable types.

This patch changes bcache to require this property, and slightly
changes the API to make it easier to use when copying a single object.
It also makes the new 'insert' template methods return the correct
type.

1 files changed, 24 insertions, 1 deletions

diff --git a/gdb/bcache.h b/gdb/bcache.h
index 17a0988..a77cd00 100644
--- a/gdb/bcache.h
+++ b/gdb/bcache.h
@@ -152,7 +152,26 @@ struct bcache
      were newly added to the cache, or to false if the bytes were
      found in the cache.  */
 
-  const void *insert (const void *addr, int length, bool *added = nullptr);
+  template<typename T, typename = gdb::Requires<std::is_trivially_copyable<T>>>
+  const T *insert (const T *addr, int length, bool *added = nullptr)
+  {
+    return (const T *) this->insert ((const void *) addr, length, added);
+  }
+
+  /* Find a copy of OBJECT in this bcache.  If BCACHE has never seen
+     those bytes before, add a copy of them to BCACHE.  In either
+     case, return a pointer to BCACHE's copy of that string.  Since
+     the cached value is meant to be read-only, return a const buffer.
+     If ADDED is not NULL, set *ADDED to true if the bytes were newly
+     added to the cache, or to false if the bytes were found in the
+     cache.  */
+
+  template<typename T, typename = gdb::Requires<std::is_trivially_copyable<T>>>
+  const T *insert (const T &object, bool *added = nullptr)
+  {
+    return (const T *) this->insert ((const void *) &object, sizeof (object),
+				     added);
+  }
 
   /* Print statistics on this bcache's memory usage and efficacity at
      eliminating duplication.  TYPE should be a string describing the
@@ -173,6 +192,10 @@ protected:
 
 private:
 
+  /* Implementation of the templated 'insert' methods.  */
+
+  const void *insert (const void *addr, int length, bool *added);
+
   /* All the bstrings are allocated here.  */
   struct obstack m_cache {};