Provide location information for terminator characters (PR preprocessor/77672)

substring_loc::get_location currently fails for the final terminator
character in a STRING_CST from the C frontend, so that format_warning_va
falls back to using the location of the string as a whole.

This patch tweaks things [1] so that we use the final closing quote
as the location of the terminator character, as requested in
PR preprocessor/77672.

[1] specifically, cpp_interpret_string_1.

gcc/ChangeLog:
	PR preprocessor/77672
	* input.c (selftest::test_lexer_string_locations_simple): Update
	test to expect location information of the terminator character
	at the location of the final closing quote.
	(selftest::test_lexer_string_locations_hex): Likewise.
	(selftest::test_lexer_string_locations_oct): Likewise.
	(selftest::test_lexer_string_locations_letter_escape_1): Likewise.
	(selftest::test_lexer_string_locations_letter_escape_2): Likewise.
	(selftest::test_lexer_string_locations_ucn4): Likewise.
	(selftest::test_lexer_string_locations_ucn8): Likewise.
	(selftest::test_lexer_string_locations_u8): Likewise.
	(selftest::test_lexer_string_locations_utf8_source): Likewise.
	(selftest::test_lexer_string_locations_concatenation_1): Likewise.
	(selftest::test_lexer_string_locations_concatenation_2): Likewise.
	(selftest::test_lexer_string_locations_concatenation_3): Likewise.
	(selftest::test_lexer_string_locations_macro): Likewise.
	(selftest::test_lexer_string_locations_long_line): Likewise.

gcc/testsuite/ChangeLog:
	PR preprocessor/77672
	* gcc.dg/plugin/diagnostic-test-string-literals-1.c
	(test_terminator_location): New function.

libcpp/ChangeLog:
	PR preprocessor/77672
	* charset.c (cpp_interpret_string_1): Add a source_range for the
	NUL-terminator, using the location of the trailing quote of the
	final string.

From-SVN: r240434

2 files changed, 15 insertions, 1 deletions

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index e039069a714..61304cb6bcb 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,10 @@
+2016-09-23  David Malcolm  <dmalcolm@redhat.com>
+
+	PR preprocessor/77672
+	* charset.c (cpp_interpret_string_1): Add a source_range for the
+	NUL-terminator, using the location of the trailing quote of the
+	final string.
+
 2016-09-21  Jason Merrill  <jason@redhat.com>
 
 	* line-map.c (linemap_location_from_macro_definition_p): New.
diff --git a/libcpp/charset.c b/libcpp/charset.c
index 6a92ade272a..e77270a18eb 100644
--- a/libcpp/charset.c
+++ b/libcpp/charset.c
@@ -1538,9 +1538,9 @@ cpp_interpret_string_1 (cpp_reader *pfile, const cpp_string *from, size_t count,
       tbuf.len = 0;
     }
 
+  cpp_string_location_reader *loc_reader = NULL;
   for (i = 0; i < count; i++)
     {
-      cpp_string_location_reader *loc_reader = NULL;
       if (loc_readers)
 	loc_reader = &loc_readers[i];
 
@@ -1652,6 +1652,13 @@ cpp_interpret_string_1 (cpp_reader *pfile, const cpp_string *from, size_t count,
       to->text = tbuf.text;
       to->len = tbuf.len;
     }
+  /* Use the location of the trailing quote as the location of the
+     NUL-terminator.  */
+  if (loc_reader)
+    {
+      source_range range = loc_reader->get_next ();
+      out->add_range (range);
+    }
 
   return true;