c++: Fix value-init crash in template [PR93676]

	PR c++/93676 - value-init crash in template.
	* init.c (build_new_1): Don't call build_vec_init in a template.

	* g++.dg/cpp0x/nsdmi-template19.C: New test.

gcc/cp/ChangeLog

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index cb5211e..26d9a08 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,11 @@
+2020-03-04  Marek Polacek  <polacek@redhat.com>
+
+	Backported from mainline
+	2020-02-26  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/93676 - value-init crash in template.
+	* init.c (build_new_1): Don't call build_vec_init in a template.
+
 2020-03-04  Jason Merrill  <jason@redhat.com>
 	    Marek Polacek  <polacek@redhat.com>
 

gcc/cp/init.c

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 44ddc8c..fcc91fc 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -3448,13 +3448,17 @@
 	  explicit_value_init_p = true;
 	}
 
-      if (processing_template_decl && explicit_value_init_p)
+      if (processing_template_decl)
 	{
+	  /* Avoid an ICE when converting to a base in build_simple_base_path.
+	     We'll throw this all away anyway, and build_new will create
+	     a NEW_EXPR.  */
+	  tree t = fold_convert (build_pointer_type (elt_type), data_addr);
 	  /* build_value_init doesn't work in templates, and we don't need
 	     the initializer anyway since we're going to throw it away and
 	     rebuild it at instantiation time, so just build up a single
 	     constructor call to get any appropriate diagnostics.  */
-	  init_expr = cp_build_fold_indirect_ref (data_addr);
+	  init_expr = cp_build_fold_indirect_ref (t);
 	  if (type_build_ctor_call (elt_type))
 	    init_expr = build_special_member_call (init_expr,
 						   complete_ctor_identifier,

gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C

diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C
new file mode 100644
index 0000000..f3e2cb8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template19.C
@@ -0,0 +1,13 @@
+// PR c++/93676 - value-init crash in template.
+// { dg-do compile { target c++11 } }
+
+struct P {
+  int x = 0;
+};
+
+template<class T>
+struct S {
+  S() { new P[2][2]; }
+};
+
+S<int> s;