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C++ PATCH for c++/49528 (omitting destructor for temporary with constant value)
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Cc: Jakub Jelinek <jakub at redhat dot com>
- Date: Sun, 26 Jun 2011 10:00:19 -0400
- Subject: C++ PATCH for c++/49528 (omitting destructor for temporary with constant value)
The constant expression evaluation code was happily replacing an
expression involving a temporary with its constant value even if the
temporary had a destructor that needed to be run.
After fixing that, I needed to adjust expand_default_init to avoid
adding a TARGET_EXPR when we aren't really creating a temporary.
Tested x86_64-pc-linux-gnu, applying to trunk. Jakub, should this go
into 4.6.1 or .2?
commit e42fdb0afe8827e3320239e252d804e2e3bbd63d
Author: Jason Merrill <jason@redhat.com>
Date: Sat Jun 25 20:52:43 2011 -0400
PR c++/49528
* semantics.c (potential_constant_expression_1): A TARGET_EXPR
with a cleanup isn't constant.
(cxx_eval_constant_expression): Likewise.
* init.c (expand_default_init): Use maybe_constant_init.
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 3c347a4..3ceed90 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -1514,7 +1514,7 @@ expand_default_init (tree binfo, tree true_exp, tree exp, tree init, int flags,
tree fn = get_callee_fndecl (rval);
if (fn && DECL_DECLARED_CONSTEXPR_P (fn))
{
- tree e = maybe_constant_value (rval);
+ tree e = maybe_constant_init (rval);
if (TREE_CONSTANT (e))
rval = build2 (INIT_EXPR, type, exp, e);
}
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index f4aa350..5404c9f 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -7020,6 +7020,16 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t,
break;
case TARGET_EXPR:
+ /* A cleanup isn't constant. */
+ if (TARGET_EXPR_CLEANUP (t))
+ {
+ if (!allow_non_constant)
+ error ("temporary of type %qT needing destruction in a "
+ "constant expression", TREE_TYPE (t));
+ *non_constant_p = true;
+ break;
+ }
+ /* else fall through. */
case INIT_EXPR:
/* Pass false for 'addr' because these codes indicate
initialization of a temporary. */
@@ -7840,8 +7850,16 @@ potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags)
return potential_constant_expression_1 (TREE_OPERAND (t, 1),
want_rval, flags);
- case INIT_EXPR:
case TARGET_EXPR:
+ /* A cleanup isn't constant. */
+ if (TARGET_EXPR_CLEANUP (t))
+ {
+ if (flags & tf_error)
+ error ("temporary of type %qT needing destruction in a "
+ "constant expression", TREE_TYPE (t));
+ return false;
+ }
+ case INIT_EXPR:
return potential_constant_expression_1 (TREE_OPERAND (t, 1),
rval, flags);
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-cleanup.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-cleanup.C
new file mode 100644
index 0000000..b3fb9a8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-cleanup.C
@@ -0,0 +1,9 @@
+// { dg-options -std=c++0x }
+
+struct A
+{
+ int i;
+ ~A();
+};
+
+constexpr int i = A().i; // { dg-error "destruction" }
diff --git a/gcc/testsuite/g++.dg/init/ref19.C b/gcc/testsuite/g++.dg/init/ref19.C
new file mode 100644
index 0000000..ed78c93
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/ref19.C
@@ -0,0 +1,17 @@
+// PR c++/49528
+// { dg-do run }
+
+int d;
+
+struct A
+{
+ int i;
+ ~A() { ++d; };
+};
+
+int main()
+{
+ const int &r = A().i;
+ if (d != 1)
+ return 1;
+}