1 files changed, 285 insertions, 0 deletions
diff --git a/gcc/substring-locations.cc b/gcc/substring-locations.cc
new file mode 100644
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--- /dev/null
+++ b/gcc/substring-locations.cc
@@ -0,0 +1,285 @@
+/* Source locations within string literals.
+   Copyright (C) 2016-2022 Free Software Foundation, Inc.
+
+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/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "intl.h"
+#include "diagnostic.h"
+#include "cpplib.h"
+#include "tree.h"
+#include "langhooks.h"
+#include "substring-locations.h"
+#include "gcc-rich-location.h"
+
+/* format_string_diagnostic_t's ctor, giving information for use by
+   the emit_warning* member functions, as follows:
+
+   They attempt to obtain precise location information within a string
+   literal from FMT_LOC.
+
+   Case 1: if substring location is available, and is within the range of
+   the format string itself, the primary location of the
+   diagnostic is the substring range obtained from FMT_LOC, with the
+   caret at the *end* of the substring range.
+
+   For example:
+
+     test.c:90:10: warning: problem with '%i' here [-Wformat=]
+     printf ("hello %i", msg);
+                    ~^
+
+   Case 2: if the substring location is available, but is not within
+   the range of the format string, the primary location is that of the
+   format string, and a note is emitted showing the substring location.
+
+   For example:
+     test.c:90:10: warning: problem with '%i' here [-Wformat=]
+     printf("hello " INT_FMT " world", msg);
+            ^~~~~~~~~~~~~~~~~~~~~~~~~
+     test.c:19: note: format string is defined here
+     #define INT_FMT "%i"
+                      ~^
+
+   Case 3: if precise substring information is unavailable, the primary
+   location is that of the whole string passed to FMT_LOC's constructor.
+   For example:
+
+     test.c:90:10: warning: problem with '%i' here [-Wformat=]
+     printf(fmt, msg);
+            ^~~
+
+   For each of cases 1-3, if param_loc is not UNKNOWN_LOCATION, then it is used
+   as a secondary range within the warning.  For example, here it
+   is used with case 1:
+
+     test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
+     printf ("foo %s bar", long_i + long_j);
+                  ~^       ~~~~~~~~~~~~~~~
+
+   and here with case 2:
+
+     test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
+     printf ("foo " STR_FMT " bar", long_i + long_j);
+             ^~~~~~~~~~~~~~~~~~~~~  ~~~~~~~~~~~~~~~
+     test.c:89:16: note: format string is defined here
+     #define STR_FMT "%s"
+                      ~^
+
+   and with case 3:
+
+     test.c:90:10: warning: '%i' here, but arg 2 is "const char *' [-Wformat=]
+     printf(fmt, msg);
+            ^~~  ~~~
+
+   If non-NULL, then FMT_LABEL will be used to label the location within the
+   string for cases 1 and 2; if non-NULL, then PARAM_LABEL will be used to label
+   the parameter.  For example with case 1:
+
+    test.c:90:16: warning: '%s' here but arg 2 has 'long' type [-Wformat=]
+     printf ("foo %s bar", long_i + long_j);
+                  ~^       ~~~~~~~~~~~~~~~
+                                  |
+                                  int
+
+   and with case 2:
+
+     test.c:90:10: warning: problem with '%i' here [-Wformat=]
+     printf("hello " INT_FMT " world", msg);
+            ^~~~~~~~~~~~~~~~~~~~~~~~~
+     test.c:19: note: format string is defined here
+     #define INT_FMT "%i"
+                      ~^
+                       |
+                       int
+
+   If CORRECTED_SUBSTRING is non-NULL, use it for cases 1 and 2 to provide
+   a fix-it hint, suggesting that it should replace the text within the
+   substring range.  For example:
+
+     test.c:90:10: warning: problem with '%i' here [-Wformat=]
+     printf ("hello %i", msg);
+                    ~^
+                    %s
+
+*/
+
+format_string_diagnostic_t::
+format_string_diagnostic_t (const substring_loc &fmt_loc,
+			    const range_label *fmt_label,
+			    location_t param_loc,
+			    const range_label *param_label,
+			    const char *corrected_substring)
+: m_fmt_loc (fmt_loc),
+  m_fmt_label (fmt_label),
+  m_param_loc (param_loc),
+  m_param_label (param_label),
+  m_corrected_substring (corrected_substring)
+{
+}
+
+/* Emit a warning governed by option OPT, using SINGULAR_GMSGID as the
+   format string (or if PLURAL_GMSGID is different from SINGULAR_GMSGID,
+   using SINGULAR_GMSGID, PLURAL_GMSGID and N as arguments to ngettext)
+   and AP as its arguments.
+
+   Return true if a warning was emitted, false otherwise.  */
+
+bool
+format_string_diagnostic_t::emit_warning_n_va (int opt,
+					       unsigned HOST_WIDE_INT n,
+					       const char *singular_gmsgid,
+					       const char *plural_gmsgid,
+					       va_list *ap) const
+{
+  bool substring_within_range = false;
+  location_t primary_loc;
+  location_t fmt_substring_loc = UNKNOWN_LOCATION;
+  source_range fmt_loc_range
+    = get_range_from_loc (line_table, m_fmt_loc.get_fmt_string_loc ());
+  const char *err = m_fmt_loc.get_location (&fmt_substring_loc);
+  source_range fmt_substring_range
+    = get_range_from_loc (line_table, fmt_substring_loc);
+  if (err)
+    /* Case 3: unable to get substring location.  */
+    primary_loc = m_fmt_loc.get_fmt_string_loc ();
+  else
+    {
+      if (fmt_substring_range.m_start >= fmt_loc_range.m_start
+	  && fmt_substring_range.m_start <= fmt_loc_range.m_finish
+	  && fmt_substring_range.m_finish >= fmt_loc_range.m_start
+	  && fmt_substring_range.m_finish <= fmt_loc_range.m_finish)
+	/* Case 1.  */
+	{
+	  substring_within_range = true;
+	  primary_loc = fmt_substring_loc;
+	}
+      else
+	/* Case 2.  */
+	{
+	  substring_within_range = false;
+	  primary_loc = m_fmt_loc.get_fmt_string_loc ();
+	}
+    }
+
+  /* Only use fmt_label in the initial warning for case 1.  */
+  const range_label *primary_label = NULL;
+  if (substring_within_range)
+    primary_label = m_fmt_label;
+
+  auto_diagnostic_group d;
+  gcc_rich_location richloc (primary_loc, primary_label);
+
+  if (m_param_loc != UNKNOWN_LOCATION)
+    richloc.add_range (m_param_loc, SHOW_RANGE_WITHOUT_CARET, m_param_label);
+
+  if (!err && m_corrected_substring && substring_within_range)
+    richloc.add_fixit_replace (fmt_substring_range, m_corrected_substring);
+
+  diagnostic_info diagnostic;
+  if (singular_gmsgid != plural_gmsgid)
+    {
+      unsigned long gtn;
+
+      if (sizeof n <= sizeof gtn)
+	gtn = n;
+      else
+	/* Use the largest number ngettext can handle, otherwise
+	   preserve the six least significant decimal digits for
+	   languages where the plural form depends on them.  */
+	gtn = n <= ULONG_MAX ? n : n % 1000000LU + 1000000LU;
+
+      const char *text = ngettext (singular_gmsgid, plural_gmsgid, gtn);
+      diagnostic_set_info_translated (&diagnostic, text, ap, &richloc,
+				      DK_WARNING);
+    }
+  else
+    diagnostic_set_info (&diagnostic, singular_gmsgid, ap, &richloc,
+			 DK_WARNING);
+  diagnostic.option_index = opt;
+  bool warned = diagnostic_report_diagnostic (global_dc, &diagnostic);
+
+  if (!err && fmt_substring_loc && !substring_within_range)
+    /* Case 2.  */
+    if (warned)
+      {
+	/* Use fmt_label in the note for case 2.  */
+	rich_location substring_richloc (line_table, fmt_substring_loc,
+					 m_fmt_label);
+	if (m_corrected_substring)
+	  substring_richloc.add_fixit_replace (fmt_substring_range,
+					       m_corrected_substring);
+	inform (&substring_richloc,
+		"format string is defined here");
+      }
+
+  return warned;
+}
+
+/* Singular-only version of the above.  */
+
+bool
+format_string_diagnostic_t::emit_warning_va (int opt, const char *gmsgid,
+					     va_list *ap) const
+{
+  return emit_warning_n_va (opt, 0, gmsgid, gmsgid, ap);
+}
+
+/* Variadic version of the above (singular only).  */
+
+bool
+format_string_diagnostic_t::emit_warning (int opt, const char *gmsgid,
+					  ...) const
+{
+  va_list ap;
+  va_start (ap, gmsgid);
+  bool warned = emit_warning_va (opt, gmsgid, &ap);
+  va_end (ap);
+
+  return warned;
+}
+
+/* Variadic version of the above (singular vs plural).  */
+
+bool
+format_string_diagnostic_t::emit_warning_n (int opt, unsigned HOST_WIDE_INT n,
+					    const char *singular_gmsgid,
+					    const char *plural_gmsgid,
+					    ...) const
+{
+  va_list ap;
+  va_start (ap, plural_gmsgid);
+  bool warned = emit_warning_n_va (opt, n, singular_gmsgid, plural_gmsgid,
+				   &ap);
+  va_end (ap);
+
+  return warned;
+}
+
+/* Attempt to determine the source location of the substring.
+   If successful, return NULL and write the source location to *OUT_LOC.
+   Otherwise return an error message.  Error messages are intended
+   for GCC developers (to help debugging) rather than for end-users.  */
+
+const char *
+substring_loc::get_location (location_t *out_loc) const
+{
+  gcc_assert (out_loc);
+  return lang_hooks.get_substring_location (*this, out_loc);
+}