[Bug c++/20103] [4.0/4.1 regression] ICE in create_tmp_var with C99 style struct initializer

["aoliva at redhat dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From aoliva at gcc dot gnu dot org  2005-03-06 07:29 -------
Subject: Re: [PR c++/20103] failure to gimplify constructors for addressable types

On Mar  5, 2005, Mark Mitchell <mark@codesourcery.com> wrote:

> Alexandre Oliva wrote:
>> Testing now.  I was a bit surprised that the casts to (const B&)
>> weren't reported as faulty, but didn't check the standard on it.

> I'd have to check the rules -- but I'm sure it's not a problem with
> your patch.  Either its correct, or an already-present bug.

>> Ok
>> to install if testing passes?

> Yes.

Unfortunately, g++.dg/template/ctor1.C and g++.dg/template/complit1.C
regressed.  As it turned out, complit1.C was in error, and had to be
adjusted to match g++.dg/ext/complit1.C, since the only significant
difference between them was that one of them had the compound-literal
within a ctor of a template class.

ctor1.C, however, exposed a failure to handle TARGET_EXPRs while
instantiating templates.  So I extended the tsubst machinery to do it,
and now ctor1.C passes again.

I also noticed that the patch fixes g++.old-deja/g++.oliva/expr2.C,
yay!

Here's the latest version of the patch, that so far passed make -C gcc
all check-g++.  Full bootstrap and regtest on x86_64-linux-gnu still
pending.  Ok to install if it passes?

Index: gcc/cp/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c++/20103
	* semantics.c (finish_compound_literal): Wrap it in a
	target_expr.
	* pt.c (tsubst_copy_and_build): Handle TARGET_EXPR.

Index: gcc/cp/semantics.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/semantics.c,v
retrieving revision 1.463
diff -u -p -r1.463 semantics.c
--- gcc/cp/semantics.c 23 Feb 2005 05:30:48 -0000 1.463
+++ gcc/cp/semantics.c 6 Mar 2005 07:12:11 -0000
@@ -1996,7 +1996,9 @@ finish_compound_literal (tree type, tree
 	complete_array_type (type, compound_literal, 1);
     }
 
-  return compound_literal;
+  /* A compound-literal is an lvalue in C, but is it going to be
+     in ISO C++?  Assume it's an rvalue for now.  */
+  return get_target_expr (compound_literal);
 }
 
 /* Return the declaration for the function-name variable indicated by
Index: gcc/cp/pt.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/pt.c,v
retrieving revision 1.978
diff -u -p -r1.978 pt.c
--- gcc/cp/pt.c 21 Feb 2005 23:12:26 -0000 1.978
+++ gcc/cp/pt.c 6 Mar 2005 07:12:19 -0000
@@ -8744,6 +8744,26 @@ tsubst_copy_and_build (tree t, 
       return build_throw
 	(RECUR (TREE_OPERAND (t, 0)));
 
+    case TARGET_EXPR:
+      {
+	tree r = tsubst_copy (t, args, complain, in_decl);
+
+	TREE_TYPE (r) = RECUR (TREE_TYPE (t));
+	TARGET_EXPR_SLOT (r) = RECUR (TARGET_EXPR_SLOT (t));
+	TARGET_EXPR_INITIAL (r) = RECUR (TARGET_EXPR_INITIAL (t));
+	TARGET_EXPR_CLEANUP (r) = RECUR (TARGET_EXPR_CLEANUP (t));
+
+	if (TREE_TYPE (TARGET_EXPR_SLOT (t))
+	    == TREE_TYPE (TARGET_EXPR_INITIAL (t)))
+	  TREE_TYPE (TARGET_EXPR_SLOT (r)) =
+	    TREE_TYPE (TARGET_EXPR_INITIAL (r));
+
+	if (TREE_TYPE (t) == TREE_TYPE (TARGET_EXPR_SLOT (t)))
+	  TREE_TYPE (r) = TREE_TYPE (TARGET_EXPR_SLOT (r));
+
+	return r;
+      }
+
     case CONSTRUCTOR:
       {
 	tree r;
Index: gcc/testsuite/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c++/20103
	* g++.dg/tree-ssa/pr20103.C: New.
	* g++.dg/template/complit1.C: Expect error like ext/complit1.C.

Index: gcc/testsuite/g++.dg/tree-ssa/pr20103.C
===================================================================
RCS file: gcc/testsuite/g++.dg/tree-ssa/pr20103.C
diff -N gcc/testsuite/g++.dg/tree-ssa/pr20103.C
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gcc/testsuite/g++.dg/tree-ssa/pr20103.C 6 Mar 2005 07:12:35 -0000
@@ -0,0 +1,59 @@
+// PR c++/20103
+
+// { dg-do compile }
+
+// { dg-options "" }
+
+// Gimplification used to fail for (B){x}, because create_tmp_var
+// required a non-addressable type, and we didn't wrap the constructor
+// in a target_expr, ensuring it's moved to a separate decl.
+
+// Whether it is an lvalue, like in C, or an rvalue, is up to the ISO
+// C++ Commitete to decide in the second version of the C++ Standard.
+// We're going with rvalues for now.
+
+struct A
+{
+    A(const A&);
+};
+
+struct B
+{
+    A a;
+};
+
+void foo(B);
+void bar(B&); // { dg-error "in passing argument" }
+void bac(const B&);
+void bap(const B*);
+
+void baz(A &x)
+{
+    foo ((B){x});
+    bar ((B){x}); // { dg-error "non-const reference" }
+    bac ((B){x});
+    bap (&(B){x}); // { dg-error "address of temporary" }
+
+    foo ((const B&)(B){x});
+    bar ((B&)(B){x}); // { dg-error "invalid cast" }
+    bac ((const B&)(B){x});
+    bap (&(const B&)(B){x});
+}
+
+template <typename T, typename U>
+void baz(T &x)
+{
+    foo ((U){x});
+    bar ((U){x}); // { dg-error "non-const reference" }
+    bac ((U){x});
+    bap (&(U){x}); // { dg-error "address of temporary" }
+
+    foo ((const U&)(U){x});
+    bar ((U&)(U){x}); // { dg-error "invalid cast" }
+    bac ((const U&)(U){x});
+    bap (&(const U&)(U){x});
+}
+
+void bazT(A &x) {
+  baz<A,B>(x);
+}
Index: gcc/testsuite/g++.dg/template/complit1.C
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.dg/template/complit1.C,v
retrieving revision 1.3
diff -u -p -r1.3 complit1.C
--- gcc/testsuite/g++.dg/template/complit1.C 28 Dec 2002 07:48:08 -0000 1.3
+++ gcc/testsuite/g++.dg/template/complit1.C 6 Mar 2005 07:12:35 -0000
@@ -6,6 +6,6 @@ template <int D> struct C {
 };
 
 template<int D>
-C<D>::C() : d((int[]){1,2,3}) {}
+C<D>::C() : d((int[]){1,2,3}) {}  // { dg-error "assignment of arrays" }
 
-template class C<1>;
+template class C<1>; // { dg-error "instantiated from" }
Index: gcc/testsuite/g++.old-deja/g++.oliva/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c++/20103
	* expr2.C: Fixed.

Index: gcc/testsuite/g++.old-deja/g++.oliva/expr2.C
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.old-deja/g++.oliva/expr2.C,v
retrieving revision 1.5
diff -u -p -r1.5 expr2.C
--- gcc/testsuite/g++.old-deja/g++.oliva/expr2.C 1 May 2003 02:02:47 -0000 1.5
+++ gcc/testsuite/g++.old-deja/g++.oliva/expr2.C 6 Mar 2005 07:12:35 -0000
@@ -1,4 +1,4 @@
-// { dg-do run { xfail *-*-* } }
+// { dg-do run }
 
 // Copyright (C) 2000 Free Software Foundation
 

-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20103