c++: ICE on invalid concept placeholder [PR94481].

Here the 'decltype' is missing '(auto)', so open_paren was NULL, and trying
to get its location is a SEGV.  Using matching_parens avoids that problem.

gcc/cp/ChangeLog
2020-04-07  Jason Merrill  <jason@redhat.com>

	PR c++/94481
	* parser.c (cp_parser_placeholder_type_specifier): Use
	matching_parens.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 60d92798112935b9f04a9e49193825bfc02627d8..8227f28e1bf807143af9c95611594c51163a693e 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-07  Jason Merrill  <jason@redhat.com>
+
+       PR c++/94481
+       * parser.c (cp_parser_placeholder_type_specifier): Use
+       matching_parens.
+
 2020-04-07  Iain Sandoe  <iain@sandoe.co.uk>
 
        * coroutines.cc (maybe_promote_captured_temps): Ensure that

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index fbcdc9bb5fc96cf4f760ab99e480562d1dc22e02..2c33ca4dd168dc37d836ca520694c5eae6fa026f 100644 (file)
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -18367,7 +18367,7 @@ cp_parser_placeholder_type_specifier (cp_parser *parser, location_t loc,
 
   /* As per the standard, require auto or decltype(auto), except in some
      cases (template parameter lists, -fconcepts-ts enabled).  */
-  cp_token *placeholder = NULL, *open_paren = NULL, *close_paren = NULL;
+  cp_token *placeholder = NULL, *close_paren = NULL;
   if (cxx_dialect >= cxx2a)
     {
       if (cp_lexer_next_token_is_keyword (parser->lexer, RID_AUTO))
@@ -18375,12 +18375,10 @@ cp_parser_placeholder_type_specifier (cp_parser *parser, location_t loc,
       else if (cp_lexer_next_token_is_keyword (parser->lexer, RID_DECLTYPE))
        {
          placeholder = cp_lexer_consume_token (parser->lexer);
-         open_paren = cp_parser_require (parser, CPP_OPEN_PAREN,
-                                         RT_OPEN_PAREN);
+         matching_parens parens;
+         parens.require_open (parser);
          cp_parser_require_keyword (parser, RID_AUTO, RT_AUTO);
-          close_paren = cp_parser_require (parser, CPP_CLOSE_PAREN,
-                                          RT_CLOSE_PAREN,
-                                          open_paren->location);
+         close_paren = parens.require_close (parser);
        }
     }
 
@@ -18429,7 +18427,7 @@ cp_parser_placeholder_type_specifier (cp_parser *parser, location_t loc,
      results in an invented template parameter.  */
   if (parser->auto_is_implicit_function_template_parm_p)
     {
-      if (placeholder && token_is_decltype (placeholder))
+      if (close_paren)
        {
          location_t loc = make_location (placeholder->location,
                                          placeholder->location,

diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder2.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder2.C
new file mode 100644 (file)
index 0000000..b04354c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder2.C
@@ -0,0 +1,9 @@
+// PR c++/94481
+// { dg-do compile { target c++2a } }
+
+template<typename T>
+concept C = true;
+
+void foo() {
+  C decltype c = 1;            // { dg-error "" }
+}