From bf2719c5d41e8dd8a0206d0a3722c96ba5aae05c Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Fri, 27 Sep 2019 09:28:40 -0400
Subject: [PATCH 32/78] analyzer: new files: pending-diagnostic.{cc|h}

This patch adds classes used by the analyzer for handling its diagnostics
(queueing them, deduplicating them, precision-of-wording hooks).

gcc/ChangeLog:
	* analyzer/pending-diagnostic.cc: New file.
	* analyzer/pending-diagnostic.h: New file.
---
 gcc/analyzer/pending-diagnostic.cc |  61 +++++++++
 gcc/analyzer/pending-diagnostic.h  | 265 +++++++++++++++++++++++++++++++++++++
 2 files changed, 326 insertions(+)
 create mode 100644 gcc/analyzer/pending-diagnostic.cc
 create mode 100644 gcc/analyzer/pending-diagnostic.h

diff --git a/gcc/analyzer/pending-diagnostic.cc b/gcc/analyzer/pending-diagnostic.cc
new file mode 100644
index 0000000..96ab824
--- /dev/null
+++ b/gcc/analyzer/pending-diagnostic.cc
@@ -0,0 +1,61 @@
+/* Classes for analyzer diagnostics.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "gcc-plugin.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tree.h"
+#include "intl.h"
+#include "diagnostic.h"
+#include "analyzer/analyzer.h"
+#include "analyzer/pending-diagnostic.h"
+
+/* Generate a label_text by printing FMT.
+
+   Use a clone of the global_dc for formatting callbacks.
+
+   Use this evdesc::event_desc's m_colorize flag to control colorization
+   (so that e.g. we can disable it for JSON output).  */
+
+label_text
+evdesc::event_desc::formatted_print (const char *fmt, ...) const
+{
+  pretty_printer *pp = global_dc->printer->clone ();
+
+  pp_show_color (pp) = m_colorize;
+
+  text_info ti;
+  rich_location rich_loc (line_table, UNKNOWN_LOCATION);
+  va_list ap;
+  va_start (ap, fmt);
+  ti.format_spec = _(fmt);
+  ti.args_ptr = &ap;
+  ti.err_no = 0;
+  ti.x_data = NULL;
+  ti.m_richloc = &rich_loc;
+  pp_format (pp, &ti);
+  pp_output_formatted_text (pp);
+  va_end (ap);
+
+  label_text result = label_text::take (xstrdup (pp_formatted_text (pp)));
+  delete pp;
+  return result;
+}
diff --git a/gcc/analyzer/pending-diagnostic.h b/gcc/analyzer/pending-diagnostic.h
new file mode 100644
index 0000000..f1ab484
--- /dev/null
+++ b/gcc/analyzer/pending-diagnostic.h
@@ -0,0 +1,265 @@
+/* Classes for analyzer diagnostics.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   Contributed by David Malcolm <dmalcolm@redhat.com>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_ANALYZER_PENDING_DIAGNOSTIC_H
+#define GCC_ANALYZER_PENDING_DIAGNOSTIC_H
+
+#include "diagnostic-event-id.h"
+#include "analyzer/sm.h"
+
+/* Various bundles of information used for generating more precise
+   messages for events within a diagnostic_path, for passing to the
+   various "describe_*" vfuncs of pending_diagnostic.  See those
+   for more information.  */
+
+namespace evdesc {
+
+struct event_desc
+{
+  event_desc (bool colorize) : m_colorize (colorize) {}
+
+  label_text formatted_print (const char *fmt, ...) const
+    ATTRIBUTE_GCC_DIAG(2,3);
+
+  bool m_colorize;
+};
+
+/* For use by pending_diagnostic::describe_state_change.  */
+
+struct state_change : public event_desc
+{
+  state_change (bool colorize,
+		tree expr,
+		tree origin,
+		state_machine::state_t old_state,
+		state_machine::state_t new_state,
+		diagnostic_event_id_t event_id)
+  : event_desc (colorize),
+    m_expr (expr), m_origin (origin),
+    m_old_state (old_state), m_new_state (new_state),
+    m_event_id (event_id)
+  {}
+
+  tree m_expr;
+  tree m_origin;
+  state_machine::state_t m_old_state;
+  state_machine::state_t m_new_state;
+  diagnostic_event_id_t m_event_id;
+};
+
+/* For use by pending_diagnostic::describe_call_with_state.  */
+
+struct call_with_state : public event_desc
+{
+  call_with_state (bool colorize,
+		   tree caller_fndecl, tree callee_fndecl,
+		   tree expr, state_machine::state_t state)
+  : event_desc (colorize),
+    m_caller_fndecl (caller_fndecl),
+    m_callee_fndecl (callee_fndecl),
+    m_expr (expr),
+    m_state (state)
+  {
+  }
+
+  tree m_caller_fndecl;
+  tree m_callee_fndecl;
+  tree m_expr;
+  state_machine::state_t m_state;
+};
+
+/* For use by pending_diagnostic::describe_return_of_state.  */
+
+struct return_of_state : public event_desc
+{
+  return_of_state (bool colorize,
+		   tree caller_fndecl, tree callee_fndecl,
+		   state_machine::state_t state)
+  : event_desc (colorize),
+    m_caller_fndecl (caller_fndecl),
+    m_callee_fndecl (callee_fndecl),
+    m_state (state)
+  {
+  }
+
+  tree m_caller_fndecl;
+  tree m_callee_fndecl;
+  state_machine::state_t m_state;
+};
+
+/* For use by pending_diagnostic::describe_final_event.  */
+
+struct final_event : public event_desc
+{
+  final_event (bool colorize,
+	       tree expr, state_machine::state_t state)
+  : event_desc (colorize),
+    m_expr (expr), m_state (state)
+  {}
+
+  tree m_expr;
+  state_machine::state_t m_state;
+};
+
+} /* end of namespace evdesc */
+
+/* An abstract base class for capturing information about a diagnostic in
+   a form that is ready to emit at a later point (or be rejected).
+   Each kind of diagnostic will have a concrete subclass of
+   pending_diagnostic.
+
+   Normally, gcc diagnostics are emitted using va_list, which can't be
+   portably stored for later use, so we have to use an "emit" virtual
+   function.
+
+   This class also supports comparison, so that multiple pending_diagnostic
+   instances can be de-duplicated.
+
+   As well as emitting a diagnostic, the class has various "precision of
+   wording" virtual functions, for generating descriptions for events
+   within a diagnostic_path.  These are optional, but implementing these
+   allows for more precise wordings than the more generic
+   implementation.  */
+
+class pending_diagnostic
+{
+ public:
+  virtual ~pending_diagnostic () {}
+
+  /* Vfunc for emitting the diagnostic.  The rich_location will have been
+     populated with a diagnostic_path.
+     Return true if a diagnostic is actually emitted.  */
+  virtual bool emit (rich_location *) = 0;
+
+  /* Hand-coded RTTI: get an ID for the subclass.  */
+  virtual const char *get_kind () const = 0;
+
+  /* Compare for equality with OTHER, which might be of a different
+     subclass.  */
+
+  bool equal_p (const pending_diagnostic &other)
+  {
+    /* Check for pointer equality on the IDs from get_kind.  */
+    if (get_kind () != other.get_kind ())
+      return false;
+    /* Call vfunc now we know they have the same ID: */
+    return subclass_equal_p (other);
+  }
+
+  /* A vfunc for testing for equality, where we've already
+     checked they have the same ID.  See pending_diagnostic_subclass
+     below for a convenience subclass for implementing this.  */
+  virtual bool subclass_equal_p (const pending_diagnostic &other) const = 0;
+
+  /* For greatest precision-of-wording, the various following "describe_*"
+     virtual functions give the pending diagnostic a way to describe events
+     in a diagnostic_path in terms that make sense for that diagnostic.
+
+     In each case, return a non-NULL label_text to give the event a custom
+     description; NULL otherwise (falling back on a more generic
+     description).  */
+
+  /* Precision-of-wording vfunc for describing a critical state change
+     within the diagnostic_path.
+
+     For example, a double-free diagnostic might use the descriptions:
+     - "first 'free' happens here"
+     - "second 'free' happens here"
+     for the pertinent events, whereas a use-after-free might use the
+     descriptions:
+     - "freed here"
+     - "use after free here"
+     Note how in both cases the first event is a "free": the best
+     description to use depends on the diagnostic.  */
+
+  virtual label_text describe_state_change (const evdesc::state_change &)
+  {
+    /* Default no-op implementation.  */
+    return label_text ();
+  }
+
+  /* Precision-of-wording vfunc for describing an interprocedural call
+     carrying critial state for the diagnostic, from caller to callee.
+
+     For example a double-free diagnostic might use:
+     - "passing freed pointer 'ptr' in call to 'deallocator' from 'test'"
+     to make it clearer how the freed value moves from caller to
+     callee.  */
+
+  virtual label_text describe_call_with_state (const evdesc::call_with_state &)
+  {
+    /* Default no-op implementation.  */
+    return label_text ();
+  }
+
+  /* Precision-of-wording vfunc for describing an interprocedural return
+     within the diagnostic_path that carries critial state for the
+     diagnostic, from callee back to caller.
+
+     For example, a deref-of-unchecked-malloc diagnostic might use:
+     - "returning possibly-NULL pointer to 'make_obj' from 'allocator'"
+     to make it clearer how the unchecked value moves from callee
+     back to caller.  */
+
+  virtual label_text describe_return_of_state (const evdesc::return_of_state &)
+  {
+    /* Default no-op implementation.  */
+    return label_text ();
+  }
+
+  /* Precision-of-wording vfunc for describing the final event within a
+     diagnostic_path.
+
+     For example a double-free diagnostic might use:
+      - "second 'free' here; first 'free' was at (3)"
+     and a use-after-free might use
+      - "use after 'free' here; memory was freed at (2)".  */
+
+  virtual label_text describe_final_event (const evdesc::final_event &)
+  {
+    /* Default no-op implementation.  */
+    return label_text ();
+  }
+
+  /* End of precision-of-wording vfuncs.  */
+};
+
+/* A template to make it easier to make subclasses of pending_diagnostic.
+
+   This uses the curiously-recurring template pattern, to implement
+   pending_diagnostic::subclass_equal_p by casting and calling
+   the operator==
+
+   This assumes that BASE_OTHER has already been checked to have
+   been of the same subclass (which pending_diagnostic::equal_p does).  */
+
+template <class Subclass>
+class pending_diagnostic_subclass : public pending_diagnostic
+{
+ public:
+  bool subclass_equal_p (const pending_diagnostic &base_other) const
+    FINAL OVERRIDE
+  {
+    const Subclass &other = (const Subclass &)base_other;
+    return *(const Subclass*)this == other;
+  }
+};
+
+#endif /* GCC_ANALYZER_PENDING_DIAGNOSTIC_H */
-- 
1.8.5.3

