[gcc r13-463] c++: array {}-init [PR105589]

[gcc r13-463] c++: array {}-init [PR105589]

[Jason Merrill]

https://gcc.gnu.org/g:ce46d6041358052dfa26f3720732f0357c5d72e7

commit r13-463-gce46d6041358052dfa26f3720732f0357c5d72e7
Author: Jason Merrill <jason@redhat.com>
Date:   Fri May 13 16:07:10 2022 -0400

    c++: array {}-init [PR105589]
    
    My patch for 105191 made us use build_value_init more frequently from
    build_vec_init_expr, but build_value_init doesn't like to be called to
    initialize a class in a template.  That's caused trouble in the past, and
    seems like a strange restriction, so let's fix it.
    
            PR c++/105589
            PR c++/105191
            PR c++/92385
    
    gcc/cp/ChangeLog:
    
            * init.cc (build_value_init): Handle class in template.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/initlist-array16.C: New test.

Diff:
---
 gcc/cp/init.cc                                |  7 +++----
 gcc/testsuite/g++.dg/cpp0x/initlist-array16.C | 11 +++++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index f1ed9336dc9..a4a0a0ac0c2 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -343,10 +343,6 @@ build_value_init (tree type, tsubst_flags_t complain)
      A program that calls for default-initialization or
      value-initialization of an entity of reference type is ill-formed.  */
 
-  /* The AGGR_INIT_EXPR tweaking below breaks in templates.  */
-  gcc_assert (!processing_template_decl
-	      || (SCALAR_TYPE_P (type) || TREE_CODE (type) == ARRAY_TYPE));
-
   if (CLASS_TYPE_P (type) && type_build_ctor_call (type))
     {
       tree ctor
@@ -354,6 +350,9 @@ build_value_init (tree type, tsubst_flags_t complain)
 				     NULL, type, LOOKUP_NORMAL, complain);
       if (ctor == error_mark_node || TREE_CONSTANT (ctor))
 	return ctor;
+      if (processing_template_decl)
+	/* The AGGR_INIT_EXPR tweaking below breaks in templates.  */
+	return build_min (CAST_EXPR, type, NULL_TREE);
       tree fn = NULL_TREE;
       if (TREE_CODE (ctor) == CALL_EXPR)
 	fn = get_callee_fndecl (ctor);
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-array16.C b/gcc/testsuite/g++.dg/cpp0x/initlist-array16.C
new file mode 100644
index 00000000000..bb1d8d84704
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-array16.C
@@ -0,0 +1,11 @@
+// PR c++/105589
+// { dg-do compile { target c++11 } }
+
+struct X { X(); };
+
+struct array { X m[2]; };
+
+template<class>
+void f() {
+  array w = array{};
+}