1/* Source locations within string literals.
2 Copyright (C) 2016-2025 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along 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#include "diagnostic-highlight-colors.h"
31
32const char *const
33format_string_diagnostic_t::highlight_color_format_string
34 = highlight_colors::expected;
35
36const char *const
37format_string_diagnostic_t::highlight_color_param
38 = highlight_colors::actual;
39
40/* format_string_diagnostic_t's ctor, giving information for use by
41 the emit_warning* member functions, as follows:
42
43 They attempt to obtain precise location information within a string
44 literal from FMT_LOC.
45
46 Case 1: if substring location is available, and is within the range of
47 the format string itself, the primary location of the
48 diagnostic is the substring range obtained from FMT_LOC, with the
49 caret at the *end* of the substring range.
50
51 For example:
52
53 test.c:90:10: warning: problem with '%i' here [-Wformat=]
54 printf ("hello %i", msg);
55 ~^
56
57 Case 2: if the substring location is available, but is not within
58 the range of the format string, the primary location is that of the
59 format string, and a note is emitted showing the substring location.
60
61 For example:
62 test.c:90:10: warning: problem with '%i' here [-Wformat=]
63 printf("hello " INT_FMT " world", msg);
64 ^~~~~~~~~~~~~~~~~~~~~~~~~
65 test.c:19: note: format string is defined here
66 #define INT_FMT "%i"
67 ~^
68
69 Case 3: if precise substring information is unavailable, the primary
70 location is that of the whole string passed to FMT_LOC's constructor.
71 For example:
72
73 test.c:90:10: warning: problem with '%i' here [-Wformat=]
74 printf(fmt, msg);
75 ^~~
76
77 For each of cases 1-3, if param_loc is not UNKNOWN_LOCATION, then it is used
78 as a secondary range within the warning. For example, here it
79 is used with case 1:
80
81 test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
82 printf ("foo %s bar", long_i + long_j);
83 ~^ ~~~~~~~~~~~~~~~
84
85 and here with case 2:
86
87 test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
88 printf ("foo " STR_FMT " bar", long_i + long_j);
89 ^~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~
90 test.c:89:16: note: format string is defined here
91 #define STR_FMT "%s"
92 ~^
93
94 and with case 3:
95
96 test.c:90:10: warning: '%i' here, but arg 2 is "const char *' [-Wformat=]
97 printf(fmt, msg);
98 ^~~ ~~~
99
100 If non-NULL, then FMT_LABEL will be used to label the location within the
101 string for cases 1 and 2; if non-NULL, then PARAM_LABEL will be used to label
102 the parameter. For example with case 1:
103
104 test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
105 printf ("foo %s bar", long_i + long_j);
106 ~^ ~~~~~~~~~~~~~~~
107 |
108 int
109
110 and with case 2:
111
112 test.c:90:10: warning: problem with '%i' here [-Wformat=]
113 printf("hello " INT_FMT " world", msg);
114 ^~~~~~~~~~~~~~~~~~~~~~~~~
115 test.c:19: note: format string is defined here
116 #define INT_FMT "%i"
117 ~^
118 |
119 int
120
121 If CORRECTED_SUBSTRING is non-NULL, use it for cases 1 and 2 to provide
122 a fix-it hint, suggesting that it should replace the text within the
123 substring range. For example:
124
125 test.c:90:10: warning: problem with '%i' here [-Wformat=]
126 printf ("hello %i", msg);
127 ~^
128 %s
129
130*/
131
132format_string_diagnostic_t::
133format_string_diagnostic_t (const substring_loc &fmt_loc,
134 const range_label *fmt_label,
135 location_t param_loc,
136 const range_label *param_label,
137 const char *corrected_substring)
138: m_fmt_loc (fmt_loc),
139 m_fmt_label (fmt_label),
140 m_param_loc (param_loc),
141 m_param_label (param_label),
142 m_corrected_substring (corrected_substring)
143{
144}
145
146/* Emit a warning governed by option OPTION_ID, using SINGULAR_GMSGID as the
147 format string (or if PLURAL_GMSGID is different from SINGULAR_GMSGID,
148 using SINGULAR_GMSGID, PLURAL_GMSGID and N as arguments to ngettext)
149 and AP as its arguments.
150
151 Return true if a warning was emitted, false otherwise. */
152
153bool
154format_string_diagnostic_t::emit_warning_n_va (diagnostic_option_id option_id,
155 unsigned HOST_WIDE_INT n,
156 const char *singular_gmsgid,
157 const char *plural_gmsgid,
158 va_list *ap) const
159{
160 bool substring_within_range = false;
161 location_t primary_loc;
162 location_t fmt_substring_loc = UNKNOWN_LOCATION;
163 source_range fmt_loc_range
164 = get_range_from_loc (set: line_table, loc: m_fmt_loc.get_fmt_string_loc ());
165 const char *err = m_fmt_loc.get_location (out_loc: &fmt_substring_loc);
166 source_range fmt_substring_range
167 = get_range_from_loc (set: line_table, loc: fmt_substring_loc);
168 if (err)
169 /* Case 3: unable to get substring location. */
170 primary_loc = m_fmt_loc.get_fmt_string_loc ();
171 else
172 {
173 if (fmt_substring_range.m_start >= fmt_loc_range.m_start
174 && fmt_substring_range.m_start <= fmt_loc_range.m_finish
175 && fmt_substring_range.m_finish >= fmt_loc_range.m_start
176 && fmt_substring_range.m_finish <= fmt_loc_range.m_finish)
177 /* Case 1. */
178 {
179 substring_within_range = true;
180 primary_loc = fmt_substring_loc;
181 }
182 else
183 /* Case 2. */
184 {
185 substring_within_range = false;
186 primary_loc = m_fmt_loc.get_fmt_string_loc ();
187 }
188 }
189
190 /* Only use fmt_label in the initial warning for case 1. */
191 const range_label *primary_label = NULL;
192 if (substring_within_range)
193 primary_label = m_fmt_label;
194
195 auto_diagnostic_group d;
196 gcc_rich_location richloc (primary_loc, primary_label,
197 highlight_color_format_string);
198
199 if (m_param_loc != UNKNOWN_LOCATION)
200 richloc.add_range (loc: m_param_loc, range_display_kind: SHOW_RANGE_WITHOUT_CARET, label: m_param_label,
201 highlight_color: highlight_color_param);
202
203 if (!err && m_corrected_substring && substring_within_range)
204 richloc.add_fixit_replace (src_range: fmt_substring_range, new_content: m_corrected_substring);
205
206 diagnostic_info diagnostic;
207 if (singular_gmsgid != plural_gmsgid)
208 {
209 unsigned long gtn;
210
211 if (sizeof n <= sizeof gtn)
212 gtn = n;
213 else
214 /* Use the largest number ngettext can handle, otherwise
215 preserve the six least significant decimal digits for
216 languages where the plural form depends on them. */
217 gtn = n <= ULONG_MAX ? n : n % 1000000LU + 1000000LU;
218
219 const char *text = ngettext (msgid1: singular_gmsgid, msgid2: plural_gmsgid, n: gtn);
220 diagnostic_set_info_translated (&diagnostic, text, ap, &richloc,
221 DK_WARNING);
222 }
223 else
224 diagnostic_set_info (&diagnostic, singular_gmsgid, ap, &richloc,
225 DK_WARNING);
226 diagnostic.option_id = option_id;
227 bool warned = diagnostic_report_diagnostic (context: global_dc, diagnostic: &diagnostic);
228
229 if (!err && fmt_substring_loc && !substring_within_range)
230 /* Case 2. */
231 if (warned)
232 {
233 /* Use fmt_label in the note for case 2. */
234 rich_location substring_richloc
235 (line_table, fmt_substring_loc,
236 m_fmt_label,
237 highlight_color_format_string);
238 if (m_corrected_substring)
239 substring_richloc.add_fixit_replace (src_range: fmt_substring_range,
240 new_content: m_corrected_substring);
241 inform (&substring_richloc,
242 "format string is defined here");
243 }
244
245 return warned;
246}
247
248/* Singular-only version of the above. */
249
250bool
251format_string_diagnostic_t::emit_warning_va (diagnostic_option_id option_id,
252 const char *gmsgid,
253 va_list *ap) const
254{
255 return emit_warning_n_va (option_id, n: 0, singular_gmsgid: gmsgid, plural_gmsgid: gmsgid, ap);
256}
257
258/* Variadic version of the above (singular only). */
259
260bool
261format_string_diagnostic_t::emit_warning (diagnostic_option_id option_id,
262 const char *gmsgid,
263 ...) const
264{
265 va_list ap;
266 va_start (ap, gmsgid);
267 bool warned = emit_warning_va (option_id, gmsgid, ap: &ap);
268 va_end (ap);
269
270 return warned;
271}
272
273/* Variadic version of the above (singular vs plural). */
274
275bool
276format_string_diagnostic_t::emit_warning_n (diagnostic_option_id option_id,
277 unsigned HOST_WIDE_INT n,
278 const char *singular_gmsgid,
279 const char *plural_gmsgid,
280 ...) const
281{
282 va_list ap;
283 va_start (ap, plural_gmsgid);
284 bool warned = emit_warning_n_va (option_id, n, singular_gmsgid, plural_gmsgid,
285 ap: &ap);
286 va_end (ap);
287
288 return warned;
289}
290
291/* Attempt to determine the source location of the substring.
292 If successful, return NULL and write the source location to *OUT_LOC.
293 Otherwise return an error message. Error messages are intended
294 for GCC developers (to help debugging) rather than for end-users. */
295
296const char *
297substring_loc::get_location (location_t *out_loc) const
298{
299 gcc_assert (out_loc);
300 return lang_hooks.get_substring_location (*this, out_loc);
301}
302

source code of gcc/substring-locations.cc