c++: EH and partially constructed aggr temp [PR66139]

Now that PR94041 is fixed, I can return to addressing PR66139, missing
cleanups for partially constructed aggregate temporaries.  My previous
approach of calling split_nonconstant_init in cp_gimplify_init_expr broke
because gimplification is too late to be introducing destructor calls.  So
instead I now call it under cp_fold_function, just before cp_genericize;
doing it from cp_genericize itself ran into trouble with the rewriting of
invisible references.

So now the prediction in cp_gimplify_expr that cp_gimplify_init_expr
might need to replace references to TARGET_EXPR_SLOT within
TARGET_EXPR_INITIAL has come to pass.  constexpr.c already had the simple
search-and-replace tree walk I needed, but it needed to be fixed to actually
replace all occurrences instead of just the first one.

Handling of VEC_INIT_EXPR at gimplify time had similar issues that we worked
around with build_vec_init_elt, so I'm moving that to cp_fold_function as
well.  But it seems that build_vec_init_elt is still useful for setting the
VEC_INIT_EXPR_IS_CONSTEXPR flag, so I'm leaving it alone.

This also fixes 52320, because build_aggr_init of each X from build_vec_init
builds an INIT_EXPR rather than call split_nonconstant_init at that point,
and now that INIT_EXPR gets split later.

	PR c++/66139
	PR c++/52320

gcc/cp/ChangeLog:

	* constexpr.c (replace_decl): Rename from replace_result_decl.
	* cp-tree.h (replace_decl): Declare it.
	* cp-gimplify.c (cp_gimplify_init_expr): Call it.
	(cp_gimplify_expr): Don't handle VEC_INIT_EXPR.
	(cp_genericize_init, cp_genericize_init_expr)
	(cp_genericize_target_expr): New.
	(cp_fold_r): Call them.
	* tree.c (build_array_copy): Add a TARGET_EXPR.
	* typeck2.c (digest_init_r): Look through a TARGET_EXPR.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/initlist116.C: New test.
	* g++.dg/cpp0x/initlist117.C: New test.
	* g++.dg/cpp0x/lambda/lambda-eh.C: New test.
	* g++.dg/eh/aggregate1.C: New test.

1 files changed, 8 insertions, 7 deletions

diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 964e40e..4c1135b 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -737,12 +737,12 @@ build_cplus_new (tree type, tree init, tsubst_flags_t complain)
    intialization as a proxy for the full array initialization to get things
    marked as used and any appropriate diagnostics.
 
-   Since we're deferring building the actual constructor calls until
-   gimplification time, we need to build one now and throw it away so
-   that the relevant constructor gets mark_used before cgraph decides
-   what functions are needed.  Here we assume that init is either
-   NULL_TREE, void_type_node (indicating value-initialization), or
-   another array to copy.  */
+   This used to be necessary because we were deferring building the actual
+   constructor calls until gimplification time; now we only do it to set
+   VEC_INIT_EXPR_IS_CONSTEXPR.
+
+   We assume that init is either NULL_TREE, void_type_node (indicating
+   value-initialization), or another array to copy.  */
 
 static tree
 build_vec_init_elt (tree type, tree init, tsubst_flags_t complain)
@@ -858,7 +858,8 @@ diagnose_non_constexpr_vec_init (tree expr)
 tree
 build_array_copy (tree init)
 {
-  return build_vec_init_expr (TREE_TYPE (init), init, tf_warning_or_error);
+  return get_target_expr (build_vec_init_expr
+			  (TREE_TYPE (init), init, tf_warning_or_error));
 }
 
 /* Build a TARGET_EXPR using INIT to initialize a new temporary of the