gcc/substring-locations.c

   1 /* Source locations within string literals.
   2    Copyright (C) 2016-2017 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_range is non-NULL, 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                    const source_range *param_range,
 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_range)
 140     {
 141       location_t param_loc = make_location (param_range->m_start,
 142                                             param_range->m_start,
 143                                             param_range->m_finish);
 144       richloc.add_range (param_loc, false);
 145     }
 146
 147   if (!err && corrected_substring && substring_within_range)
 148     richloc.add_fixit_replace (fmt_substring_range, corrected_substring);
 149
 150   diagnostic_info diagnostic;
 151   diagnostic_set_info (&diagnostic, gmsgid, ap, &richloc, DK_WARNING);
 152   diagnostic.option_index = opt;
 153   bool warned = report_diagnostic (&diagnostic);
 154
 155   if (!err && fmt_substring_loc && !substring_within_range)
 156     /* Case 2.  */
 157     if (warned)
 158       {
 159         rich_location substring_richloc (line_table, fmt_substring_loc);
 160         if (corrected_substring)
 161           substring_richloc.add_fixit_replace (fmt_substring_range,
 162                                                corrected_substring);
 163         inform_at_rich_loc (&substring_richloc,
 164                             "format string is defined here");
 165       }
 166
 167   return warned;
 168 }
 169
 170 /* Variadic call to format_warning_va.  */
 171
 172 bool
 173 format_warning_at_substring (const substring_loc &fmt_loc,
 174                              const source_range *param_range,
 175                              const char *corrected_substring,
 176                              int opt, const char *gmsgid, ...)
 177 {
 178   va_list ap;
 179   va_start (ap, gmsgid);
 180   bool warned = format_warning_va (fmt_loc, param_range, corrected_substring,
 181                                    opt, gmsgid, &ap);
 182   va_end (ap);
 183
 184   return warned;
 185 }
 186
 187 /* Attempt to determine the source location of the substring.
 188    If successful, return NULL and write the source location to *OUT_LOC.
 189    Otherwise return an error message.  Error messages are intended
 190    for GCC developers (to help debugging) rather than for end-users.  */
 191
 192 const char *
 193 substring_loc::get_location (location_t *out_loc) const
 194 {
 195   gcc_assert (out_loc);
 196   return lang_hooks.get_substring_location (*this, out_loc);
 197 }