From: Marek Polacek <polacek@redhat.com>
Date: Wed, 10 Mar 2021 01:55:14 +0000 (-0500)
Subject: c++: Fix error-recovery with requires expression [PR99500]
X-Git-Tag: basepoints/gcc-12~530
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=bd9b262fa9243e08fefa4973f08d1f09f6694ba0;p=thirdparty%2Fgcc.git

c++: Fix error-recovery with requires expression [PR99500]

This fixes an ICE on invalid code where one of the parameters was
error_mark_node and thus resetting its DECL_CONTEXT crashed.

gcc/cp/ChangeLog:

	PR c++/99500
	* parser.c (cp_parser_requirement_parameter_list): Handle
	error_mark_node.

gcc/testsuite/ChangeLog:

	PR c++/99500
	* g++.dg/cpp2a/concepts-err3.C: New test.
---

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index d4e485930a4f..ced4bd5a0e51 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -28839,8 +28839,11 @@ cp_parser_requirement_parameter_list (cp_parser *parser)
       if (parm == void_list_node || parm == explicit_void_list_node)
 	break;
       tree decl = TREE_VALUE (parm);
-      DECL_CONTEXT (decl) = NULL_TREE;
-      CONSTRAINT_VAR_P (decl) = true;
+      if (decl != error_mark_node)
+	{
+	  DECL_CONTEXT (decl) = NULL_TREE;
+	  CONSTRAINT_VAR_P (decl) = true;
+	}
     }
 
   return parms;
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-err3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-err3.C
new file mode 100644
index 000000000000..9427fd5c5a65
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-err3.C
@@ -0,0 +1,4 @@
+// PR c++/99500
+// { dg-do compile { target c++20 } }
+
+bool b = requires (bool a, int a) { requires true; }; // { dg-error "conflicting declaration" }