re PR c++/84925 (ICE with segfault in __PRETTY_FUNCTION__)

	PR c++/84925
	* pt.c (enclosing_instantiation_of): Check if fn is null.

	* g++.dg/cpp1z/lambda-__func__.C: New test.

From-SVN: r258660

gcc/cp/ChangeLog

+2018-03-19  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/84925
+	* pt.c (enclosing_instantiation_of): Check if fn is null.
+
 2018-03-16  Jason Merrill  <jason@redhat.com>
 
 	PR c++/71834 - template-id with too few arguments.

gcc/cp/pt.c

@@ -12917,7 +12917,7 @@ enclosing_instantiation_of (tree otctx)
       for (; flambda_count < lambda_count && fn && LAMBDA_FUNCTION_P (fn);
 	   fn = decl_function_context (fn))
 	++flambda_count;
-      if (DECL_TEMPLATE_INFO (fn)
+      if ((fn && DECL_TEMPLATE_INFO (fn))
 	  ? most_general_template (fn) != most_general_template (tctx)
 	  : fn != tctx)
 	continue;

gcc/testsuite/ChangeLog

+2018-03-19  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/84925
+	* g++.dg/cpp1z/lambda-__func__.C: New test.
+
 2018-03-19  Maxim Ostapenko  <m.ostapenko@samsung.com>
 
 	PR sanitizer/78651

gcc/testsuite/g++.dg/cpp1z/lambda-__func__.C

+// PR c++/84925
+// { dg-options "-std=c++17" }
+
+template <typename>
+struct A {
+  static const int value = 0;
+  static auto constexpr fn = [] { return __func__; };
+};
+
+template <typename type>
+int x = A<type>::value;
+
+auto s = x<int>;