From 5546e1604519ca18e2e3f96f59ce636bb69d773a Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Wed, 25 Nov 2015 13:58:11 -0500
Subject: [PATCH] re PR sanitizer/67941 (calls on function pointer from a
 captureless lambda cause ubsan warning)

	PR c++/67941
	* lambda.c (maybe_add_lambda_conv_op): Mark _FUN as
	no_sanitize_undefined.

From-SVN: r230897
---
 gcc/cp/ChangeLog                    | 4 ++++
 gcc/cp/lambda.c                     | 6 ++++++
 gcc/testsuite/g++.dg/ubsan/null-6.C | 5 +++++
 3 files changed, 15 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ubsan/null-6.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 968482f3a3e..635db4e46e9 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,9 @@
 2015-11-25  Jason Merrill  <jason@redhat.com>
 
+	PR c++/67941
+	* lambda.c (maybe_add_lambda_conv_op): Mark _FUN as
+	no_sanitize_undefined.
+
 	* cp-ubsan.c (cp_ubsan_instrument_vptr_p): Use
 	do_ubsan_in_current_function.
 
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 5fe34731e4f..f9b686b16e8 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -1053,6 +1053,12 @@ maybe_add_lambda_conv_op (tree type)
   if (generic_lambda_p)
     fn = add_inherited_template_parms (fn, DECL_TI_TEMPLATE (callop));
 
+  /* Don't UBsan this function; we're deliberately calling op() with a null
+     object argument.  */
+  tree attrs = build_tree_list (get_identifier ("no_sanitize_undefined"),
+				NULL_TREE);
+  cplus_decl_attributes (&fn, attrs, 0);
+
   add_method (type, fn, NULL_TREE);
 
   if (nested)
diff --git a/gcc/testsuite/g++.dg/ubsan/null-6.C b/gcc/testsuite/g++.dg/ubsan/null-6.C
new file mode 100644
index 00000000000..2efe5c2b8cc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ubsan/null-6.C
@@ -0,0 +1,5 @@
+// PR c++/67941
+// { dg-do run { target c++11 } }
+// { dg-options -fsanitize=null }
+
+int main(){ (+[](){})(); }