Here, the problem was that we weren't calling convert_from_reference
when substituting the argument for a non-type template parameter as we
do in other places that might produce a reference. Once that change was
made, I had to adjust a couple of other functions to deal with getting a
reference ref instead of a raw reference.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 176d3b3cbf489dfc485576a3d8a204da3e95acde
Author: Jason Merrill <ja...@redhat.com>
Date: Wed Jul 27 00:01:15 2011 -0700
PR c++/49808
* pt.c (tsubst) [TEMPLATE_PARM_INDEX]: Call convert_from_reference.
(convert_nontype_argument, tsubst_template_arg): Handle its output.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b9e09af..a3cd956 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5556,41 +5556,45 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
function). We just strip everything and get to the arg.
See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
for examples. */
- if (TREE_CODE (expr) == NOP_EXPR)
+ if (TYPE_REF_OBJ_P (type) || TYPE_REFFN_P (type))
{
- if (TYPE_REF_OBJ_P (type) || TYPE_REFFN_P (type))
+ tree probe_type, probe = expr;
+ if (REFERENCE_REF_P (probe))
+ probe = TREE_OPERAND (probe, 0);
+ probe_type = TREE_TYPE (probe);
+ if (TREE_CODE (probe) == NOP_EXPR)
{
/* ??? Maybe we could use convert_from_reference here, but we
would need to relax its constraints because the NOP_EXPR
could actually change the type to something more cv-qualified,
and this is not folded by convert_from_reference. */
- tree addr = TREE_OPERAND (expr, 0);
- gcc_assert (TREE_CODE (expr_type) == REFERENCE_TYPE);
+ tree addr = TREE_OPERAND (probe, 0);
+ gcc_assert (TREE_CODE (probe_type) == REFERENCE_TYPE);
gcc_assert (TREE_CODE (addr) == ADDR_EXPR);
gcc_assert (TREE_CODE (TREE_TYPE (addr)) == POINTER_TYPE);
gcc_assert (same_type_ignoring_top_level_qualifiers_p
- (TREE_TYPE (expr_type),
+ (TREE_TYPE (probe_type),
TREE_TYPE (TREE_TYPE (addr))));
expr = TREE_OPERAND (addr, 0);
expr_type = TREE_TYPE (expr);
}
+ }
- /* We could also generate a NOP_EXPR(ADDR_EXPR()) when the
- parameter is a pointer to object, through decay and
- qualification conversion. Let's strip everything. */
- else if (TYPE_PTROBV_P (type))
- {
- STRIP_NOPS (expr);
- gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
- gcc_assert (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE);
- /* Skip the ADDR_EXPR only if it is part of the decay for
- an array. Otherwise, it is part of the original argument
- in the source code. */
- if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == ARRAY_TYPE)
- expr = TREE_OPERAND (expr, 0);
- expr_type = TREE_TYPE (expr);
- }
+ /* We could also generate a NOP_EXPR(ADDR_EXPR()) when the
+ parameter is a pointer to object, through decay and
+ qualification conversion. Let's strip everything. */
+ else if (TREE_CODE (expr) == NOP_EXPR && TYPE_PTROBV_P (type))
+ {
+ STRIP_NOPS (expr);
+ gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
+ gcc_assert (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE);
+ /* Skip the ADDR_EXPR only if it is part of the decay for
+ an array. Otherwise, it is part of the original argument
+ in the source code. */
+ if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == ARRAY_TYPE)
+ expr = TREE_OPERAND (expr, 0);
+ expr_type = TREE_TYPE (expr);
}
/* [temp.arg.nontype]/5, bullet 1
@@ -8941,6 +8945,10 @@ tsubst_template_arg (tree t, tree args, tsubst_flags_t complain, tree in_decl)
/*integral_constant_expression_p=*/true);
if (!(complain & tf_warning))
--c_inhibit_evaluation_warnings;
+ /* Preserve the raw-reference nature of T. */
+ if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == REFERENCE_TYPE
+ && REFERENCE_REF_P (r))
+ r = TREE_OPERAND (r, 0);
}
return r;
}
@@ -10981,7 +10989,7 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
}
else
/* TEMPLATE_TEMPLATE_PARM or TEMPLATE_PARM_INDEX. */
- return unshare_expr (arg);
+ return convert_from_reference (unshare_expr (arg));
}
if (level == 1)
diff --git a/gcc/testsuite/g++.dg/template/nontype24.C b/gcc/testsuite/g++.dg/template/nontype24.C
new file mode 100644
index 0000000..57fbe43
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/nontype24.C
@@ -0,0 +1,16 @@
+// PR c++/49808
+
+template <class X, X g>
+struct A
+{
+ A() { float r = g(0); }
+};
+
+struct f_t
+{
+ float operator() (float) const { return 1; }
+};
+
+f_t f;
+
+A<f_t&, f> x;
