PR c++/93280 - ICE with aggregate assignment and DMI.

I recently added an assert to cp-gimplify to catch any
TARGET_EXPR_DIRECT_INIT_P being expanded without a target object, and this
testcase found one.  We started out with a TARGET_EXPR around the
CONSTRUCTOR, which would normally mean that the member initializer would be
used to directly initialize the appropriate member of whatever object the
TARGET_EXPR ends up initializing.  But then gimplify_modify_expr_rhs
stripped the TARGET_EXPR in order to assign directly from the elements of
the CONSTRUCTOR, leaving no object for the TARGET_EXPR_DIRECT_INIT_P to
initialize.  I considered setting CONSTRUCTOR_PLACEHOLDER_BOUNDARY in that
case, which implies TARGET_EXPR_NO_ELIDE, but decided that there's no
particular reason the A initializer needs to initialize a member of a B
rather than a distinct A object, so let's only set TARGET_EXPR_DIRECT_INIT_P
when we're using the DMI in a constructor.

	* init.c (get_nsdmi): Set TARGET_EXPR_DIRECT_INIT_P here.
	* typeck2.c (digest_nsdmi_init): Not here.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 47d55e5066d608a96d9bdca9fe1058eaa8b3a88a..3ca5d7a11b43607ffb756ca3977838208aff2a51 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-16  Jason Merrill  <jason@redhat.com>
+
+       PR c++/93280 - ICE with aggregate assignment and DMI.
+       * init.c (get_nsdmi): Set TARGET_EXPR_DIRECT_INIT_P here.
+       * typeck2.c (digest_nsdmi_init): Not here.
+
 2020-01-15  Paolo Carlini  <paolo.carlini@oracle.com>
 
        PR c++/91073

diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index ba80474e6ac6f5d500cf050bf0c17bbcdc6fabc2..543d127abcd8079256385022d0c9d8aee1f6f9f0 100644 (file)
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -655,6 +655,10 @@ get_nsdmi (tree member, bool in_ctor, tsubst_flags_t complain)
   if (simple_target)
     init = TARGET_EXPR_INITIAL (init);
   init = break_out_target_exprs (init, /*loc*/true);
+  if (in_ctor && init && TREE_CODE (init) == TARGET_EXPR)
+    /* This expresses the full initialization, prevent perform_member_init from
+       calling another constructor (58162).  */
+    TARGET_EXPR_DIRECT_INIT_P (init) = true;
   if (simple_target && TREE_CODE (init) != CONSTRUCTOR)
     /* Now put it back so C++17 copy elision works.  */
     init = get_target_expr (init);

diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index f36a5649ae65b63c53be034635bdcc2fa9e535c9..371b203c29bd6d208db92794e772179c9569db2f 100644 (file)
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -1369,9 +1369,6 @@ digest_nsdmi_init (tree decl, tree init, tsubst_flags_t complain)
       && CP_AGGREGATE_TYPE_P (type))
     init = reshape_init (type, init, complain);
   init = digest_init_flags (type, init, flags, complain);
-  if (TREE_CODE (init) == TARGET_EXPR)
-    /* This represents the whole initialization.  */
-    TARGET_EXPR_DIRECT_INIT_P (init) = true;
   return init;
 }
 \f