diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a382235d7cce..fc75879d14fd 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-04-04  Marek Polacek  <polacek@redhat.com>
+	    Jason Merrill  <jason@redhat.com>
+
+	PR c++/94155 - crash in gimplifier with paren init of aggregates.
+	* init.c (build_vec_init): Fill in indexes.
+
 2020-04-04  Jason Merrill  <jason@redhat.com>
 
 	PR c++/91377
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 27623cf4db19..ea95a3bc9103 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -4438,6 +4438,8 @@ build_vec_init (tree base, tree maxindex, tree init,
 	    errors = true;
 	  if (try_const)
 	    {
+	      if (!field)
+		field = size_int (idx);
 	      tree e = maybe_constant_init (one_init);
 	      if (reduced_constant_expression_p (e))
 		{
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 88bab5d3d19c..29830633d793 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/94155 - crash in gimplifier with paren init of aggregates.
+	* g++.dg/cpp2a/paren-init22.C: New test.
+
 2020-04-05  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* g++.dg/coroutines/torture/co-await-14-template-traits.C: Rename...
diff --git a/gcc/testsuite/g++.dg/cpp2a/paren-init22.C b/gcc/testsuite/g++.dg/cpp2a/paren-init22.C
new file mode 100644
index 000000000000..1b2959e7731c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/paren-init22.C
@@ -0,0 +1,15 @@
+// PR c++/94155 - crash in gimplifier with paren init of aggregates.
+// { dg-do compile { target c++2a } }
+
+struct S { int i, j; };
+
+struct A {
+  S s;
+  constexpr A(S e) : s(e) {}
+};
+
+void
+f()
+{
+  A g[1]({{1, 1}});
+}