re PR c++/91925 (-fpack-struct causes a decltype with template to ICE)

	PR c++/91925
	* c-warn.c (check_alignment_of_packed_member): Ignore FIELD_DECLs
	with NULL DECL_FIELD_OFFSET.

	* g++.dg/conversion/packed2.C: New test.

From-SVN: r276415

gcc/c-family/ChangeLog

+2019-10-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/91925
+	* c-warn.c (check_alignment_of_packed_member): Ignore FIELD_DECLs
+	with NULL DECL_FIELD_OFFSET.
+
 2019-10-01  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* c-pretty-print.c (pp_c_specifier_qualifier_list): If a vector type

gcc/c-family/c-warn.c

@@ -2798,6 +2798,8 @@ check_alignment_of_packed_member (tree type, tree field, bool rvalue)
   /* Check alignment of the data member.  */
   if (TREE_CODE (field) == FIELD_DECL
       && (DECL_PACKED (field) || TYPE_PACKED (TREE_TYPE (field)))
+      /* Ignore FIELDs not laid out yet.  */
+      && DECL_FIELD_OFFSET (field)
       && (!rvalue || TREE_CODE (TREE_TYPE (field)) == ARRAY_TYPE))
     {
       /* Check the expected alignment against the field alignment.  */

gcc/testsuite/ChangeLog

+2019-10-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/91925
+	* g++.dg/conversion/packed2.C: New test.
+
 2019-10-01  Bill Schmidt  <wschmdit@linux.ibm.com>
 
 	* gcc.target/powerpc/pr91275.c: New.

gcc/testsuite/g++.dg/conversion/packed2.C

+// PR c++/91925
+// { dg-do compile { target c++11 } }
+// { dg-options "-fpack-struct" }
+
+struct A {};
+int foo (A);
+struct B {
+  A a;
+  decltype (foo (a)) p;
+};
+template <typename T> T bar (T);
+class C {
+  A a;
+  decltype (bar (a)) p;
+};