re PR c++/80145 ([c++1y] ICE after failed return type deduction)

/cp
2017-05-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/80145
	* decl.c (finish_function): To improve error recovery, change the
	logic for calling apply_deduced_return_type.

/testsuite
2017-05-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/80145
	* g++.dg/cpp1y/auto-fn37.C: New.
	* g++.dg/cpp1y/auto-fn38.C: Likewise.

From-SVN: r247828

gcc/cp/ChangeLog

+2017-05-10  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/80145
+	* decl.c (finish_function): To improve error recovery, change the
+	logic for calling apply_deduced_return_type.
+
 2017-05-09  Jason Merrill  <jason@redhat.com>
 
 	* class.c (check_bases): Ignore empty bases.

gcc/cp/decl.c

@@ -15562,16 +15562,19 @@ finish_function (int flags)
   if (!processing_template_decl && FNDECL_USED_AUTO (fndecl)
       && TREE_TYPE (fntype) == current_function_auto_return_pattern)
     {
-      if (!is_auto (current_function_auto_return_pattern)
-	  && !current_function_returns_value && !current_function_returns_null)
+      if (is_auto (current_function_auto_return_pattern))
+	{
+	  apply_deduced_return_type (fndecl, void_type_node);
+	  fntype = TREE_TYPE (fndecl);
+	}
+      else if (!current_function_returns_value
+	       && !current_function_returns_null)
 	{
 	  error ("no return statements in function returning %qT",
 		 current_function_auto_return_pattern);
 	  inform (input_location, "only plain %<auto%> return type can be "
 		  "deduced to %<void%>");
 	}
-      apply_deduced_return_type (fndecl, void_type_node);
-      fntype = TREE_TYPE (fndecl);
     }
 
   // If this is a concept, check that the definition is reasonable.

gcc/testsuite/ChangeLog

+2017-05-10  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/80145
+	* g++.dg/cpp1y/auto-fn37.C: New.
+	* g++.dg/cpp1y/auto-fn38.C: Likewise.
+
 2017-05-09  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	PR target/68163

gcc/testsuite/g++.dg/cpp1y/auto-fn37.C

+// PR c++/80145
+// { dg-do compile { target c++14 } }
+
+auto* foo() { return 0; }  // { dg-error "unable to deduce" }
+auto* foo();

gcc/testsuite/g++.dg/cpp1y/auto-fn38.C

+// PR c++/80145
+// { dg-do compile { target c++14 } }
+
+auto* foo() { }  // { dg-error "no return statements" }
+auto* foo();