gcc/substring-locations.cc

   1 /* Source locations within string literals.
   2    Copyright (C) 2016-2023 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 "intl.h"
  24 #include "diagnostic.h"
  25 #include "cpplib.h"
  26 #include "tree.h"
  27 #include "langhooks.h"
  28 #include "substring-locations.h"
  29 #include "gcc-rich-location.h"
  30
  31 /* format_string_diagnostic_t's ctor, giving information for use by
  32    the emit_warning* member functions, as follows:
  33
  34    They attempt to obtain precise location information within a string
  35    literal from FMT_LOC.
  36
  37    Case 1: if substring location is available, and is within the range of
  38    the format string itself, the primary location of the
  39    diagnostic is the substring range obtained from FMT_LOC, with the
  40    caret at the *end* of the substring range.
  41
  42    For example:
  43
  44      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  45      printf ("hello %i", msg);
  46                     ~^
  47
  48    Case 2: if the substring location is available, but is not within
  49    the range of the format string, the primary location is that of the
  50    format string, and a note is emitted showing the substring location.
  51
  52    For example:
  53      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  54      printf("hello " INT_FMT " world", msg);
  55             ^~~~~~~~~~~~~~~~~~~~~~~~~
  56      test.c:19: note: format string is defined here
  57      #define INT_FMT "%i"
  58                       ~^
  59
  60    Case 3: if precise substring information is unavailable, the primary
  61    location is that of the whole string passed to FMT_LOC's constructor.
  62    For example:
  63
  64      test.c:90:10: warning: problem with '%i' here [-Wformat=]
  65      printf(fmt, msg);
  66             ^~~
  67
  68    For each of cases 1-3, if param_loc is not UNKNOWN_LOCATION, then it is used
  69    as a secondary range within the warning.  For example, here it
  70    is used with case 1:
  71
  72      test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
  73      printf ("foo %s bar", long_i + long_j);
  74                   ~^       ~~~~~~~~~~~~~~~
  75
  76    and here with case 2:
  77
  78      test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
  79      printf ("foo " STR_FMT " bar", long_i + long_j);
  80              ^~~~~~~~~~~~~~~~~~~~~  ~~~~~~~~~~~~~~~
  81      test.c:89:16: note: format string is defined here
  82      #define STR_FMT "%s"
  83                       ~^
  84
  85    and with case 3:
  86
  87      test.c:90:10: warning: '%i' here, but arg 2 is "const char *' [-Wformat=]
  88      printf(fmt, msg);
  89             ^~~  ~~~
  90
  91    If non-NULL, then FMT_LABEL will be used to label the location within the
  92    string for cases 1 and 2; if non-NULL, then PARAM_LABEL will be used to label
  93    the parameter.  For example with case 1:
  94
  95     test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
  96      printf ("foo %s bar", long_i + long_j);
  97                   ~^       ~~~~~~~~~~~~~~~
  98                                   |
  99                                   int
 100
 101    and with case 2:
 102
 103      test.c:90:10: warning: problem with '%i' here [-Wformat=]
 104      printf("hello " INT_FMT " world", msg);
 105             ^~~~~~~~~~~~~~~~~~~~~~~~~
 106      test.c:19: note: format string is defined here
 107      #define INT_FMT "%i"
 108                       ~^
 109                        |
 110                        int
 111
 112    If CORRECTED_SUBSTRING is non-NULL, use it for cases 1 and 2 to provide
 113    a fix-it hint, suggesting that it should replace the text within the
 114    substring range.  For example:
 115
 116      test.c:90:10: warning: problem with '%i' here [-Wformat=]
 117      printf ("hello %i", msg);
 118                     ~^
 119                     %s
 120
 121 */
 122
 123 format_string_diagnostic_t::
 124 format_string_diagnostic_t (const substring_loc &fmt_loc,
 125                             const range_label *fmt_label,
 126                             location_t param_loc,
 127                             const range_label *param_label,
 128                             const char *corrected_substring)
 129 : m_fmt_loc (fmt_loc),
 130   m_fmt_label (fmt_label),
 131   m_param_loc (param_loc),
 132   m_param_label (param_label),
 133   m_corrected_substring (corrected_substring)
 134 {
 135 }
 136
 137 /* Emit a warning governed by option OPT, using SINGULAR_GMSGID as the
 138    format string (or if PLURAL_GMSGID is different from SINGULAR_GMSGID,
 139    using SINGULAR_GMSGID, PLURAL_GMSGID and N as arguments to ngettext)
 140    and AP as its arguments.
 141
 142    Return true if a warning was emitted, false otherwise.  */
 143
 144 bool
 145 format_string_diagnostic_t::emit_warning_n_va (int opt,
 146                                                unsigned HOST_WIDE_INT n,
 147                                                const char *singular_gmsgid,
 148                                                const char *plural_gmsgid,
 149                                                va_list *ap) const
 150 {
 151   bool substring_within_range = false;
 152   location_t primary_loc;
 153   location_t fmt_substring_loc = UNKNOWN_LOCATION;
 154   source_range fmt_loc_range
 155     = get_range_from_loc (line_table, m_fmt_loc.get_fmt_string_loc ());
 156   const char *err = m_fmt_loc.get_location (&fmt_substring_loc);
 157   source_range fmt_substring_range
 158     = get_range_from_loc (line_table, fmt_substring_loc);
 159   if (err)
 160     /* Case 3: unable to get substring location.  */
 161     primary_loc = m_fmt_loc.get_fmt_string_loc ();
 162   else
 163     {
 164       if (fmt_substring_range.m_start >= fmt_loc_range.m_start
 165           && fmt_substring_range.m_start <= fmt_loc_range.m_finish
 166           && fmt_substring_range.m_finish >= fmt_loc_range.m_start
 167           && fmt_substring_range.m_finish <= fmt_loc_range.m_finish)
 168         /* Case 1.  */
 169         {
 170           substring_within_range = true;
 171           primary_loc = fmt_substring_loc;
 172         }
 173       else
 174         /* Case 2.  */
 175         {
 176           substring_within_range = false;
 177           primary_loc = m_fmt_loc.get_fmt_string_loc ();
 178         }
 179     }
 180
 181   /* Only use fmt_label in the initial warning for case 1.  */
 182   const range_label *primary_label = NULL;
 183   if (substring_within_range)
 184     primary_label = m_fmt_label;
 185
 186   auto_diagnostic_group d;
 187   gcc_rich_location richloc (primary_loc, primary_label);
 188
 189   if (m_param_loc != UNKNOWN_LOCATION)
 190     richloc.add_range (m_param_loc, SHOW_RANGE_WITHOUT_CARET, m_param_label);
 191
 192   if (!err && m_corrected_substring && substring_within_range)
 193     richloc.add_fixit_replace (fmt_substring_range, m_corrected_substring);
 194
 195   diagnostic_info diagnostic;
 196   if (singular_gmsgid != plural_gmsgid)
 197     {
 198       unsigned long gtn;
 199
 200       if (sizeof n <= sizeof gtn)
 201         gtn = n;
 202       else
 203         /* Use the largest number ngettext can handle, otherwise
 204            preserve the six least significant decimal digits for
 205            languages where the plural form depends on them.  */
 206         gtn = n <= ULONG_MAX ? n : n % 1000000LU + 1000000LU;
 207
 208       const char *text = ngettext (singular_gmsgid, plural_gmsgid, gtn);
 209       diagnostic_set_info_translated (&diagnostic, text, ap, &richloc,
 210                                       DK_WARNING);
 211     }
 212   else
 213     diagnostic_set_info (&diagnostic, singular_gmsgid, ap, &richloc,
 214                          DK_WARNING);
 215   diagnostic.option_index = opt;
 216   bool warned = diagnostic_report_diagnostic (global_dc, &diagnostic);
 217
 218   if (!err && fmt_substring_loc && !substring_within_range)
 219     /* Case 2.  */
 220     if (warned)
 221       {
 222         /* Use fmt_label in the note for case 2.  */
 223         rich_location substring_richloc (line_table, fmt_substring_loc,
 224                                          m_fmt_label);
 225         if (m_corrected_substring)
 226           substring_richloc.add_fixit_replace (fmt_substring_range,
 227                                                m_corrected_substring);
 228         inform (&substring_richloc,
 229                 "format string is defined here");
 230       }
 231
 232   return warned;
 233 }
 234
 235 /* Singular-only version of the above.  */
 236
 237 bool
 238 format_string_diagnostic_t::emit_warning_va (int opt, const char *gmsgid,
 239                                              va_list *ap) const
 240 {
 241   return emit_warning_n_va (opt, 0, gmsgid, gmsgid, ap);
 242 }
 243
 244 /* Variadic version of the above (singular only).  */
 245
 246 bool
 247 format_string_diagnostic_t::emit_warning (int opt, const char *gmsgid,
 248                                           ...) const
 249 {
 250   va_list ap;
 251   va_start (ap, gmsgid);
 252   bool warned = emit_warning_va (opt, gmsgid, &ap);
 253   va_end (ap);
 254
 255   return warned;
 256 }
 257
 258 /* Variadic version of the above (singular vs plural).  */
 259
 260 bool
 261 format_string_diagnostic_t::emit_warning_n (int opt, unsigned HOST_WIDE_INT n,
 262                                             const char *singular_gmsgid,
 263                                             const char *plural_gmsgid,
 264                                             ...) const
 265 {
 266   va_list ap;
 267   va_start (ap, plural_gmsgid);
 268   bool warned = emit_warning_n_va (opt, n, singular_gmsgid, plural_gmsgid,
 269                                    &ap);
 270   va_end (ap);
 271
 272   return warned;
 273 }
 274
 275 /* Attempt to determine the source location of the substring.
 276    If successful, return NULL and write the source location to *OUT_LOC.
 277    Otherwise return an error message.  Error messages are intended
 278    for GCC developers (to help debugging) rather than for end-users.  */
 279
 280 const char *
 281 substring_loc::get_location (location_t *out_loc) const
 282 {
 283   gcc_assert (out_loc);
 284   return lang_hooks.get_substring_location (*this, out_loc);
 285 }