paths.h

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/* Paths through the code associated with a diagnostic.
   Copyright (C) 2019-2025 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_DIAGNOSTICS_PATHS_H
#define GCC_DIAGNOSTICS_PATHS_H
 
#include "diagnostic.h" /* for ATTRIBUTE_GCC_DIAG.  */
#include "diagnostics/event-id.h"
#include "diagnostics/logical-locations.h"
 
namespace diagnostics {
  namespace digraphs {
    class digraph;
  } // namespace digraphs
  namespace logical_locations {
    class manager;
  } // logical_locations
  class sarif_builder;
  class sarif_object;
} //namespace diagnostics
 
namespace diagnostics {
namespace paths {
 
/* A diagnostics::paths::path is an optional additional piece of metadata associated
   with a diagnostic (via its rich_location).
 
   It describes a sequence of events predicted by the compiler that
   lead to the problem occurring, with their locations in the user's source,
   and text descriptions.
 
   For example, the following error has a 3-event path:
 
     test.c: In function 'demo':
     test.c:29:5: error: passing NULL as argument 1 to 'PyList_Append' which
       requires a non-NULL parameter
        29 |     PyList_Append(list, item);
           |     ^~~~~~~~~~~~~~~~~~~~~~~~~
       'demo': events 1-3
        25 |   list = PyList_New(0);
           |          ^~~~~~~~~~~~~
           |          |
           |          (1) when 'PyList_New' fails, returning NULL
        26 |
        27 |   for (i = 0; i < count; i++) {
           |   ~~~
           |   |
           |   (2) when 'i < count'
        28 |     item = PyLong_FromLong(random());
        29 |     PyList_Append(list, item);
           |     ~~~~~~~~~~~~~~~~~~~~~~~~~
           |     |
           |     (3) when calling 'PyList_Append', passing NULL from (1) as argument 1
 
    The diagnostic-printing code has consolidated the path into a single
    run of events, since all the events are near each other and within the same
    function; more complicated examples (such as interprocedural paths)
    might be printed as multiple runs of events.  */
 
/* Abstract base classes, describing events within a path, and the paths
   themselves.  */
 
/* One event within a path.  */
 
class event
{
 public:
  /* Enums for giving a sense of what this event means.
     Roughly corresponds to SARIF v2.1.0 section 3.38.8.  */
  enum class verb
  {
    unknown,
 
    acquire,
    release,
    enter,
    exit,
    call,
    return_,
    branch,
 
    danger,
 
    // Special control flow operations:
    throw_,
    catch_,
    unwind_, // unwinding stack frame(s) during exception-handling
    setjmp_,
    longjmp_
  };
  enum class noun
  {
    unknown,
 
    taint,
    sensitive, // this one isn't in SARIF v2.1.0; filed as https://github.com/oasis-tcs/sarif-spec/issues/530
    function,
    lock,
    memory,
    resource
  };
  enum class property
  {
    unknown,
 
    true_,
    false_
  };
  /* A bundle of such enums, allowing for descriptions of the meaning of
     an event, such as
     - "acquire memory": meaning (verb::acquire, noun::memory)
     - "take true branch"": meaning (verb::branch, property::true)
     - "return from function": meaning (verb::return, noun::function)
     etc, as per SARIF's threadFlowLocation "kinds" property
     (SARIF v2.1.0 section 3.38.8).  */
  struct meaning
  {
    meaning ()
    : m_verb (verb::unknown),
      m_noun (noun::unknown),
      m_property (property::unknown)
    {
    }
    meaning (enum verb verb)
    : m_verb (verb), m_noun (noun::unknown), m_property (property::unknown)
    {
    }
    meaning (enum verb verb, enum noun noun)
    : m_verb (verb), m_noun (noun), m_property (property::unknown)
    {
    }
    meaning (enum verb verb, enum property property)
    : m_verb (verb), m_noun (noun::unknown), m_property (property)
    {
    }
 
    void dump_to_pp (pretty_printer *pp) const;
 
    static const char *maybe_get_verb_str (enum verb);
    static const char *maybe_get_noun_str (enum noun);
    static const char *maybe_get_property_str (enum property);
 
    enum verb m_verb;
    enum noun m_noun;
    enum property m_property;
  };
 
  virtual ~event () {}
 
  virtual location_t get_location () const = 0;
 
  /* Stack depth, so that consumers can visualize the interprocedural
     calls, returns, and frame nesting.  */
  virtual int get_stack_depth () const = 0;
 
  /* Print a localized (and possibly colorized) description of this event.  */
  virtual void print_desc (pretty_printer &pp) const = 0;
 
  /* Get a logical location for this event, or null if there is none.  */
  virtual logical_locations::key get_logical_location () const = 0;
 
  virtual meaning get_meaning () const = 0;
 
  /* True iff we should draw a line connecting this event to the
     next event (e.g. to highlight control flow).  */
  virtual bool connect_to_next_event_p () const = 0;
 
  virtual thread_id_t get_thread_id () const = 0;
 
  /* Hook for SARIF output to allow for adding diagnostic-specific
     properties to the threadFlowLocation object's property bag.  */
  virtual void
  maybe_add_sarif_properties (sarif_builder &,
                              sarif_object &/*thread_flow_loc_obj*/) const
  {
  }
 
  /* Hook for capturing state at this event, potentially for visualizing
     in HTML output, or for adding to SARIF.  */
  virtual std::unique_ptr<digraphs::digraph>
  maybe_make_diagnostic_state_graph (bool debug) const;
 
  label_text get_desc (pretty_printer &ref_pp) const;
};
 
/* Abstract base class representing a thread of execution within
   a diagnostics::paths::path.
   Each event is associated with one thread.
   Typically there is just one thread per diagnostics::paths::path. */
 
class thread
{
public:
  virtual ~thread () {}
  virtual label_text get_name (bool can_colorize) const = 0;
};
 
/* Abstract base class for getting at a sequence of events.  */
 
class path
{
 public:
  virtual ~path () {}
  virtual unsigned num_events () const = 0;
  virtual const event & get_event (int idx) const = 0;
  virtual unsigned num_threads () const = 0;
  virtual const thread &
  get_thread (thread_id_t) const = 0;
 
  /* Return true iff the two events are both within the same function,
     or both outside of any function.  */
  virtual bool
  same_function_p (int event_idx_a,
                   int event_idx_b) const = 0;
 
  bool interprocedural_p () const;
  bool multithreaded_p () const;
 
  const logical_locations::manager &get_logical_location_manager () const
  {
    return m_logical_loc_mgr;
  }
 
protected:
  path (const logical_locations::manager &logical_loc_mgr)
  : m_logical_loc_mgr (logical_loc_mgr)
  {
  }
 
private:
  bool get_first_event_in_a_function (unsigned *out_idx) const;
 
  const logical_locations::manager &m_logical_loc_mgr;
};
 
} // namespace paths
} // namespace diagnostics
 
/* Concrete subclasses of the above can be found in
   simple-diagnostic-path.h.  */
 
extern void debug (diagnostics::paths::path *path);
 
#endif /* ! GCC_DIAGNOSTICS_PATHS_H */