Convert label_text to C++11 move semantics

libcpp's class label_text stores a char * for a string and a flag saying
whether it owns the buffer.  I added this class before we could use
C++11, and so to avoid lots of copying it required an explicit call
to label_text::maybe_free to potentially free the buffer.

Now that we can use C++11, this patch removes label_text::maybe_free in
favor of doing the cleanup in the destructor, and using C++ move
semantics to avoid any copying.  This allows lots of messy cleanup code
to be eliminated in favor of implicit destruction (mostly in the
analyzer).

No functional change intended.

gcc/analyzer/ChangeLog:
	* call-info.cc (call_info::print): Update for removal of
	label_text::maybe_free in favor of automatic memory management.
	* checker-path.cc (checker_event::dump): Likewise.
	(checker_event::prepare_for_emission): Likewise.
	(state_change_event::get_desc): Likewise.
	(superedge_event::should_filter_p): Likewise.
	(start_cfg_edge_event::get_desc): Likewise.
	(warning_event::get_desc): Likewise.
	(checker_path::dump): Likewise.
	(checker_path::debug): Likewise.
	* diagnostic-manager.cc
	(diagnostic_manager::prune_for_sm_diagnostic): Likewise.
	(diagnostic_manager::prune_interproc_events): Likewise.
	* program-state.cc (sm_state_map::to_json): Likewise.
	* region.cc (region::to_json): Likewise.
	* sm-malloc.cc (inform_nonnull_attribute): Likewise.
	* store.cc (binding_map::to_json): Likewise.
	(store::to_json): Likewise.
	* svalue.cc (svalue::to_json): Likewise.

gcc/c-family/ChangeLog:
	* c-format.cc (range_label_for_format_type_mismatch::get_text):
	Update for removal of label_text::maybe_free in favor of automatic
	memory management.

gcc/ChangeLog:
	* diagnostic-format-json.cc (json_from_location_range): Update for
	removal of label_text::maybe_free in favor of automatic memory
	management.
	* diagnostic-format-sarif.cc
	(sarif_builder::make_location_object): Likewise.
	* diagnostic-show-locus.cc (struct pod_label_text): New.
	(class line_label): Convert m_text from label_text to pod_label_text.
	(layout::print_any_labels): Move "text" to the line_label.
	* tree-diagnostic-path.cc (path_label::get_text): Update for
	removal of label_text::maybe_free in favor of automatic memory
	management.
	(event_range::print): Likewise.
	(default_tree_diagnostic_path_printer): Likewise.
	(default_tree_make_json_for_path): Likewise.

libcpp/ChangeLog:
	* include/line-map.h: Include <utility>.
	(class label_text): Delete maybe_free method in favor of a
	destructor.  Add move ctor and assignment operator.  Add deletion
	of the copy ctor and copy-assignment operator.  Rename field
	m_caller_owned to m_owned.  Add std::move where necessary; add
	moved_from member function.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 38 insertions, 8 deletions

diff --git a/libcpp/include/line-map.h b/libcpp/include/line-map.h
index 8033572..c6379ce 100644
--- a/libcpp/include/line-map.h
+++ b/libcpp/include/line-map.h
@@ -22,6 +22,8 @@ along with this program; see the file COPYING3.  If not see
 #ifndef LIBCPP_LINE_MAP_H
 #define LIBCPP_LINE_MAP_H
 
+#include <utility>
+
 #ifndef GTY
 #define GTY(x) /* nothing */
 #endif
@@ -1836,43 +1838,71 @@ class label_text
 {
 public:
   label_text ()
-  : m_buffer (NULL), m_caller_owned (false)
+  : m_buffer (NULL), m_owned (false)
   {}
 
-  void maybe_free ()
+  ~label_text ()
+  {
+    if (m_owned)
+      free (m_buffer);
+  }
+
+  /* Move ctor.  */
+  label_text (label_text &&other)
+  : m_buffer (other.m_buffer), m_owned (other.m_owned)
+  {
+    other.moved_from ();
+  }
+
+  /* Move assignment.  */
+  label_text & operator= (label_text &&other)
   {
-    if (m_caller_owned)
+    if (m_owned)
       free (m_buffer);
+    m_buffer = other.m_buffer;
+    m_owned = other.m_owned;
+    other.moved_from ();
+    return *this;
   }
 
+  /* Delete the copy ctor and copy-assignment operator.  */
+  label_text (const label_text &) = delete;
+  label_text & operator= (const label_text &) = delete;
+
   /* Create a label_text instance that borrows BUFFER from a
      longer-lived owner.  */
   static label_text borrow (const char *buffer)
   {
-    return label_text (const_cast <char *> (buffer), false);
+    return std::move (label_text (const_cast <char *> (buffer), false));
   }
 
   /* Create a label_text instance that takes ownership of BUFFER.  */
   static label_text take (char *buffer)
   {
-    return label_text (buffer, true);
+    return std::move (label_text (buffer, true));
   }
 
   /* Take ownership of the buffer, copying if necessary.  */
   char *take_or_copy ()
   {
-    if (m_caller_owned)
+    if (m_owned)
       return m_buffer;
     else
       return xstrdup (m_buffer);
   }
 
+  void moved_from ()
+  {
+    m_buffer = NULL;
+    m_owned = false;
+  }
+
   char *m_buffer;
-  bool m_caller_owned;
+  bool m_owned;
 
 private:
   label_text (char *buffer, bool owned)
-  : m_buffer (buffer), m_caller_owned (owned)
+  : m_buffer (buffer), m_owned (owned)
   {}
 };