Re: [C++ PATCH] PR 70501, ICE in verify ctor sanity

[Nathan Sidwell <nathan at acm dot org>]

On 04/06/16 07:49, Jason Merrill wrote:

> Sure, but that also seems unnecessary; vector rvalues don't have object identity
> the way class and array rvalues do.

I attach 2 patches.

70501-2.patch fixes the ICE by treating VECTOR_TYPEs thesame as PMFs in 
cxx_eval_bare_aggregate).

70501-other.patch stops finish_compound_literal wrapping VECTOR_TYPEs in a 
TARGET_EXPR.  And also moves the comments  around, as I found them a little 
confusing.  We might want to wait until 7.0 to apply that patch, as it's not a 
regression.

For avoidance of doubt I tested the first patch both with and without the second 
patch.

ok?

nathan

2016-04-06  Nathan Sidwell  <nathan@acm.org>

	PR c++/70501
	* constexpr.c (cxx_eval_bare_aggregate): Handle VECTOR_TYPE
	similarly to PMF.

	* g++.dg/init/pr70501.C: New.

Index: cp/constexpr.c
===================================================================
--- cp/constexpr.c	(revision 234768)
+++ cp/constexpr.c	(working copy)
@@ -2370,10 +2370,10 @@ cxx_eval_bare_aggregate (const constexpr
   tree type = TREE_TYPE (t);
 
   constexpr_ctx new_ctx;
-  if (TYPE_PTRMEMFUNC_P (type))
+  if (TYPE_PTRMEMFUNC_P (type) || VECTOR_TYPE_P (type))
     {
-      /* We don't really need the ctx->ctor business for a PMF, but it's
-	 simpler to use the same code.  */
+      /* We don't really need the ctx->ctor business for a PMF or
+	 vector, but it's simpler to use the same code.  */
       new_ctx = *ctx;
       new_ctx.ctor = build_constructor (type, NULL);
       new_ctx.object = NULL_TREE;
Index: testsuite/g++.dg/init/pr70501.C
===================================================================
--- testsuite/g++.dg/init/pr70501.C	(nonexistent)
+++ testsuite/g++.dg/init/pr70501.C	(working copy)
@@ -0,0 +1,11 @@
+/* { dg-options "" } Not pedantic */
+
+typedef int v4si __attribute__ ((vector_size (16)));
+
+struct S { v4si v; };
+
+void
+fn2 (int i, int j)
+{
+  struct S s = { .v = i <= j + (v4si){(1, 2)} };
+}

2016-04-06  Nathan Sidwell  <nathan@acm.org>

	* semantics.c (finish_compound_lteral): Don't wrap VECTOR_TYPEs in a
	TARGET_EXPR.

Index: cp/semantics.c
===================================================================
--- cp/semantics.c	(revision 234768)
+++ cp/semantics.c	(working copy)
@@ -2732,8 +2732,8 @@ finish_compound_literal (tree type, tree
   compound_literal = digest_init (type, compound_literal, complain);
   if (TREE_CODE (compound_literal) == CONSTRUCTOR)
     TREE_HAS_CONSTRUCTOR (compound_literal) = true;
-  /* Put static/constant array temporaries in static variables, but always
-     represent class temporaries with TARGET_EXPR so we elide copies.  */
+
+  /* Put static/constant array temporaries in static variables.  */
   if ((!at_function_scope_p () || CP_TYPE_CONST_P (type))
       && TREE_CODE (type) == ARRAY_TYPE
       && !TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)
@@ -2763,8 +2763,13 @@ finish_compound_literal (tree type, tree
 	return error_mark_node;
       return decl;
     }
-  else
-    return get_target_expr_sfinae (compound_literal, complain);
+
+  /* Represent other compound literals with TARGET_EXPR so we produce
+     an lvalue, but can elide copies.  */
+  if (!VECTOR_TYPE_P (type))
+    compound_literal = get_target_expr_sfinae (compound_literal, complain);
+
+  return compound_literal;
 }
 
 /* Return the declaration for the function-name variable indicated by