[PATCH] Fix __has_include error recovery in libcpp (PR preprocessor/88974)

[Jakub Jelinek]

Hi!

On the following testcase, 
_cpp_bracket_include -> glue_header_name emits
      if (token->type == CPP_EOF)
        {
          cpp_error (pfile, CPP_DL_ERROR, "missing terminating > character");
          break;
        }
which works, that last token has proper src_loc etc., but then 
parse_has_include as _cpp_bracket_include caller will do cpp_get_token
(pfile) again and emit another error, which is both IMHO unnecessary when
we've emitted the earlier one, but also is a different CPP_EOF from the
earlier one and so it has uninitializer src_loc etc., so diagnostics on it
doesn't work.  Looking around elsewhere in libcpp, we have in directives.c
#define SEEN_EOL() (pfile->cur_token[-1].type == CPP_EOF)
macro and if SEEN_EOL, we omit some diagnostics.

If pfile->cur_token[-1].type is CPP_EOF, we must have emitted some error
already, either the:
    cpp_error (pfile, CPP_DL_ERROR,
               "operator \"__has_include__\" requires a header string");
one or
          cpp_error (pfile, CPP_DL_ERROR, "missing terminating > character");
otherwise pfile->cur_token[-1].type must be CPP_GREATER, CPP_STRING or
CPP_HEADER_NAME, so there is no point getting another token when we know we
are at CPP_EOF and emitting another diagnostics.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2019-01-24  Jakub Jelinek  <jakub@redhat.com>

	PR preprocessor/88974
	* expr.c (parse_has_include): Don't cpp_get_token if EOL has been
	seen.

	* c-c++-common/cpp/pr88974.c: New test.

--- libcpp/expr.c.jj	2019-01-01 12:38:16.132007335 +0100
+++ libcpp/expr.c	2019-01-24 14:07:10.080774120 +0100
@@ -2238,7 +2238,9 @@ parse_has_include (cpp_reader *pfile, en
       XDELETEVEC (fname);
     }
 
-  if (paren && cpp_get_token (pfile)->type != CPP_CLOSE_PAREN)
+  if (paren
+      && pfile->cur_token[-1].type != CPP_EOF
+      && cpp_get_token (pfile)->type != CPP_CLOSE_PAREN)
     cpp_error (pfile, CPP_DL_ERROR,
 	       "missing ')' after \"__has_include__\"");
 
--- gcc/testsuite/c-c++-common/cpp/pr88974.c.jj	2019-01-24 14:25:02.271100711 +0100
+++ gcc/testsuite/c-c++-common/cpp/pr88974.c	2019-01-24 14:24:48.098334156 +0100
@@ -0,0 +1,6 @@
+/* PR preprocessor/88974 */
+/* { dg-do preprocess } */
+
+#if __has_include (<pr88974.h)
+/* { dg-error "missing terminating > character" "" { target *-*-* } .-1 } */
+#endif

	Jakub