gcc/substring-locations.c

   1 /* Source locations within string literals.
   2    Copyright (C) 2016-2018 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "diagnostic.h"
  24 #include "cpplib.h"
  25 #include "tree.h"
  26 #include "langhooks.h"
  27 #include "substring-locations.h"
  28
  29 /* Emit a warning governed by option OPT, using GMSGID as the format
  30    string and AP as its arguments.
  31
  32    Attempt to obtain precise location information within a string
  33    literal from FMT_LOC.
  34
  35    Case 1: if substring location is available, and is within the range of
  36    the format string itself, the primary location of the
  37    diagnostic is the substring range obtained from FMT_LOC, with the
  38    caret at the *end* of the substring range.
  39
  40    For example:
  41
  42      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  43      printf ("hello %i", msg);
  44                     ~^
  45
  46    Case 2: if the substring location is available, but is not within
  47    the range of the format string, the primary location is that of the
  48    format string, and an note is emitted showing the substring location.
  49
  50    For example:
  51      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  52      printf("hello " INT_FMT " world", msg);
  53             ^~~~~~~~~~~~~~~~~~~~~~~~~
  54      test.c:19: note: format string is defined here
  55      #define INT_FMT "%i"
  56                       ~^
  57
  58    Case 3: if precise substring information is unavailable, the primary
  59    location is that of the whole string passed to FMT_LOC's constructor.
  60    For example:
  61
  62      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  63      printf(fmt, msg);
  64             ^~~
  65
  66    For each of cases 1-3, if param_loc is not UNKNOWN_LOCATION, then it is used
  67    as a secondary range within the warning.  For example, here it
  68    is used with case 1:
  69
  70      test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
  71      printf ("foo %s bar", long_i + long_j);
  72                   ~^       ~~~~~~~~~~~~~~~
  73
  74    and here with case 2:
  75
  76      test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
  77      printf ("foo " STR_FMT " bar", long_i + long_j);
  78              ^~~~~~~~~~~~~~~~~~~~~  ~~~~~~~~~~~~~~~
  79      test.c:89:16: note: format string is defined here
  80      #define STR_FMT "%s"
  81                       ~^
  82
  83    and with case 3:
  84
  85      test.c:90:10: warning: '%i' here, but arg 2 is "const char *' [-Wformat=]
  86      printf(fmt, msg);
  87             ^~~  ~~~
  88
  89    If CORRECTED_SUBSTRING is non-NULL, use it for cases 1 and 2 to provide
  90    a fix-it hint, suggesting that it should replace the text within the
  91    substring range.  For example:
  92
  93      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  94      printf ("hello %i", msg);
  95                     ~^
  96                     %s
  97
  98    Return true if a warning was emitted, false otherwise.  */
  99
 100 ATTRIBUTE_GCC_DIAG (5,0)
 101 bool
 102 format_warning_va (const substring_loc &fmt_loc,
 103                    location_t param_loc,
 104                    const char *corrected_substring,
 105                    int opt, const char *gmsgid, va_list *ap)
 106 {
 107   bool substring_within_range = false;
 108   location_t primary_loc;
 109   location_t fmt_substring_loc = UNKNOWN_LOCATION;
 110   source_range fmt_loc_range
 111     = get_range_from_loc (line_table, fmt_loc.get_fmt_string_loc ());
 112   const char *err = fmt_loc.get_location (&fmt_substring_loc);
 113   source_range fmt_substring_range
 114     = get_range_from_loc (line_table, fmt_substring_loc);
 115   if (err)
 116     /* Case 3: unable to get substring location.  */
 117     primary_loc = fmt_loc.get_fmt_string_loc ();
 118   else
 119     {
 120       if (fmt_substring_range.m_start >= fmt_loc_range.m_start
 121           && fmt_substring_range.m_start <= fmt_loc_range.m_finish
 122           && fmt_substring_range.m_finish >= fmt_loc_range.m_start
 123           && fmt_substring_range.m_finish <= fmt_loc_range.m_finish)
 124         /* Case 1.  */
 125         {
 126           substring_within_range = true;
 127           primary_loc = fmt_substring_loc;
 128         }
 129       else
 130         /* Case 2.  */
 131         {
 132           substring_within_range = false;
 133           primary_loc = fmt_loc.get_fmt_string_loc ();
 134         }
 135     }
 136
 137   rich_location richloc (line_table, primary_loc);
 138
 139   if (param_loc != UNKNOWN_LOCATION)
 140     richloc.add_range (param_loc, false);
 141
 142   if (!err && corrected_substring && substring_within_range)
 143     richloc.add_fixit_replace (fmt_substring_range, corrected_substring);
 144
 145   diagnostic_info diagnostic;
 146   diagnostic_set_info (&diagnostic, gmsgid, ap, &richloc, DK_WARNING);
 147   diagnostic.option_index = opt;
 148   bool warned = diagnostic_report_diagnostic (global_dc, &diagnostic);
 149
 150   if (!err && fmt_substring_loc && !substring_within_range)
 151     /* Case 2.  */
 152     if (warned)
 153       {
 154         rich_location substring_richloc (line_table, fmt_substring_loc);
 155         if (corrected_substring)
 156           substring_richloc.add_fixit_replace (fmt_substring_range,
 157                                                corrected_substring);
 158         inform (&substring_richloc,
 159                 "format string is defined here");
 160       }
 161
 162   return warned;
 163 }
 164
 165 /* Variadic call to format_warning_va.  */
 166
 167 bool
 168 format_warning_at_substring (const substring_loc &fmt_loc,
 169                              location_t param_loc,
 170                              const char *corrected_substring,
 171                              int opt, const char *gmsgid, ...)
 172 {
 173   va_list ap;
 174   va_start (ap, gmsgid);
 175   bool warned = format_warning_va (fmt_loc, param_loc, corrected_substring,
 176                                    opt, gmsgid, &ap);
 177   va_end (ap);
 178
 179   return warned;
 180 }
 181
 182 /* Attempt to determine the source location of the substring.
 183    If successful, return NULL and write the source location to *OUT_LOC.
 184    Otherwise return an error message.  Error messages are intended
 185    for GCC developers (to help debugging) rather than for end-users.  */
 186
 187 const char *
 188 substring_loc::get_location (location_t *out_loc) const
 189 {
 190   gcc_assert (out_loc);
 191   return lang_hooks.get_substring_location (*this, out_loc);
 192 }