------- Additional Comments From aoliva at gcc dot gnu dot org 2005-03-05
14:03 -------
Subject: Re: [PR c++/20103] failure to gimplify constructors for addressable
types
On Mar 5, 2005, Alexandre Oliva <[EMAIL PROTECTED]> wrote:
> On Mar 4, 2005, Mark Mitchell <[EMAIL PROTECTED]> wrote:
>>> + foo ((B){x});
>> I don't think (B){x} should be an lvalue, C99 notwithstanding. B(3)
>> is not be an lavalue; I don't see why "(B){x}" should be.
> Works for me. We can always extend it later, should the ISO C++
> committee make a decision different from ours.
> Patch will follow hopefully later today.
For small values of later :-)
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. Ok
to install if testing passes?
Index: gcc/cp/ChangeLog
from Alexandre Oliva <[EMAIL PROTECTED]>
PR c++/20103
* semantics.c (finish_compound_literal): Wrap it in a
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 5 Mar 2005 13:56:17 -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/testsuite/ChangeLog
from Alexandre Oliva <[EMAIL PROTECTED]>
* g++.dg/tree-ssa/pr20103.C: New.
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 5 Mar 2005 13:56:31 -0000
@@ -0,0 +1,41 @@
+// 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});
+}
--
Alexandre Oliva http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer [EMAIL PROTECTED], gcc.gnu.org}
Free Software Evangelist [EMAIL PROTECTED], gnu.org}
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20103
