c++: ICE with structured bindings and m-d array [PR102594]
We ICE in decay_conversion with this test:
struct S {
S() {}
};
S arr[1][1];
auto [m](arr3);
But not when the last line is:
auto [n] = arr3;
Therefore the difference is between copy- and direct-init. In
particular, in build_vec_init we have:
if (direct_init)
from = build_tree_list (NULL_TREE, from);
and then we call build_vec_init again with init==from. Then
decay_conversion gets the TREE_LIST and it crashes.
build_aggr_init has:
/* Wrap the initializer in a CONSTRUCTOR so that build_vec_init
recognizes it as direct-initialization. */
init = build_constructor_single (init_list_type_node,
NULL_TREE, init);
CONSTRUCTOR_IS_DIRECT_INIT (init) = true;
so I propose to do the same in build_vec_init.
PR c++/102594
gcc/cp/ChangeLog:
* init.cc (build_vec_init): Build up a CONSTRUCTOR to signal
direct-initialization rather than a TREE_LIST.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/decomp61.C: New test.
Reviewed-by: Jason Merrill <jason@redhat.com>
(cherry picked from commit 96e0370f4daef29b918aafcff68c7f5e4ef397fd)
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 5a99437..f9b651b 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -4919,7 +4919,13 @@
if (xvalue)
from = move (from);
if (direct_init)
- from = build_tree_list (NULL_TREE, from);
+ {
+ /* Wrap the initializer in a CONSTRUCTOR so that
+ build_vec_init recognizes it as direct-initialization. */
+ from = build_constructor_single (init_list_type_node,
+ NULL_TREE, from);
+ CONSTRUCTOR_IS_DIRECT_INIT (from) = true;
+ }
}
else
from = NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp61.C b/gcc/testsuite/g++.dg/cpp1z/decomp61.C
new file mode 100644
index 0000000..ad0a20c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp61.C
@@ -0,0 +1,28 @@
+// PR c++/102594
+// { dg-do compile { target c++17 } }
+
+struct S {
+ S() {}
+};
+S arr1[2];
+S arr2[2][1];
+S arr3[1][1];
+auto [m](arr3);
+auto [n] = arr3;
+
+struct X {
+ int i;
+};
+
+void
+g (X x)
+{
+ auto [a, b](arr2);
+ auto [c, d] = arr2;
+ auto [e, f] = (arr2);
+ auto [i, j](arr1);
+ auto [k, l] = arr1;
+ auto [m, n] = (arr1);
+ auto [z] = x;
+ auto [y](x);
+}
