Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
The problem here was that we were building an IMPLICIT_CONV_EXPR around a
capture proxy, so that when we try to substitute that into the alias
template we are no longer within the lambda scope and fall over.
convert_nontype_argument properly calls mark_rvalue_use, which resolves the
use of the capture to its constant value. So instead of only adding an
IMPLICIT_CONV_EXPR wrapper, in this situation let's do the normal conversion
and then rewrite a NOP_EXPR/CONVERT_EXPR in the result to
IMPLICIT_CONV_EXPR.
PR c++/126828
PR c++/112632
gcc/cp/ChangeLog:
* pt.cc (dependent_implicit_conv_p): Remove.
(convert_nontype_argument_maybe_dependent): Rewrite
simple conversion when force_conv.
(tsubst_expr): Use it.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/alias-decl-nontype2.C: New test.
---
gcc/cp/pt.cc | 46 +++++++++----------
.../g++.dg/cpp0x/alias-decl-nontype2.C | 11 +++++
2 files changed, 32 insertions(+), 25 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype2.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 85204c5536e..6b8fbcd1c14 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -8881,19 +8881,6 @@ maybe_build_nontype_implicit_conv (tree type, tree arg,
bool force)
return arg;
}
-/* True if we need an IMPLICIT_CONV_EXPR for converting EXPR to TYPE, possibly
- in a FORCED context (i.e. alias or concept). */
-
-static bool
-dependent_implicit_conv_p (tree type, tree expr, bool forced)
-{
- return (dependent_type_p (type) || type_dependent_expression_p (expr)
- || (forced
- && !(same_type_ignoring_top_level_qualifiers_p
- (TREE_TYPE (expr), type))
- && value_dependent_expression_p (expr)));
-}
-
/* Convert the non-type template parameter ARG to the indicated TYPE.
If one of them is dependent, create an appropriate conversion.
FORCE_CONV is true in a forced context (i.e. alias or concept). */
@@ -8903,7 +8890,7 @@ convert_nontype_argument_maybe_dependent (tree type, tree
arg,
bool force_conv,
tsubst_flags_t complain)
{
- if (dependent_implicit_conv_p (type, arg, force_conv))
+ if (dependent_type_p (type) || type_dependent_expression_p (arg))
{
tree val = canonicalize_expr_argument (arg, complain);
return maybe_build_nontype_implicit_conv (type, val, force_conv);
@@ -8917,8 +8904,24 @@ convert_nontype_argument_maybe_dependent (tree type,
tree arg,
deciding whether or not these conversions can occur is part of
determining which function template to call, or whether a given
explicit argument specification is valid. */
- return convert_nontype_argument (type, convert_from_reference (arg),
- complain);
+ tree r = convert_nontype_argument (type, convert_from_reference (arg),
+ complain);
+
+ /* When force_conv, we need to express this conversion with
+ IMPLICIT_CONV_EXPR rather than NOP_EXPR so we go through
+ convert_nontype_argument again at substitution time for
+ e.g. narrowing checks. */
+ if (force_conv && r && CONVERT_EXPR_P (r)
+ && !same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (arg))
+ && value_dependent_expression_p (arg))
+ {
+ tree op = TREE_OPERAND (r, 0);
+ gcc_assert (same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (op),
+ TREE_TYPE (arg)));
+ r = maybe_build_nontype_implicit_conv (type, op, force_conv);
+ }
+
+ return r;
}
/* Convert the indicated template ARG as necessary to match the
@@ -21789,17 +21792,10 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
if (type == error_mark_node)
RETURN (error_mark_node);
tree expr = RECUR (TREE_OPERAND (t, 0));
- if (dependent_implicit_conv_p (type, expr,
- IMPLICIT_CONV_EXPR_FORCED (t)))
- {
- retval = copy_node (t);
- TREE_TYPE (retval) = type;
- TREE_OPERAND (retval, 0) = expr;
- RETURN (retval);
- }
if (IMPLICIT_CONV_EXPR_NONTYPE_ARG (t))
{
- tree r = convert_nontype_argument (type, expr, complain);
+ tree r = (convert_nontype_argument_maybe_dependent
+ (type, expr, IMPLICIT_CONV_EXPR_FORCED (t), complain));
if (r == NULL_TREE)
r = error_mark_node;
RETURN (r);
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype2.C
b/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype2.C
new file mode 100644
index 00000000000..067382642bf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype2.C
@@ -0,0 +1,11 @@
+// PR c++/126828
+// { dg-do compile { target c++11 } }
+
+template <int> class a{};
+template <int b> using c = a<b>;
+template <int> void d() {
+ constexpr unsigned blocksize = 8;
+ [&] {
+ c<blocksize> g;
+ };
+}
base-commit: 33600590ba53735410de9bf619171691b2703301
--
2.55.0
