Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
We've had a problem with lost conversions to template parameter types for a
while now; looking at this PR, it occurred to me that the problem is really
with alias (and concept) templates, since we do substitution of dependent
arguments into them in a way that we don't for other templates. And fixing
that specific problem is a lot simpler than adding IMPLICIT_CONV_EXPR around
all dependent template arguments the way I gave up on for 111357.
The other part of the fix was changing tsubst_expr to actually call
convert_nontype_argument instead of assuming it will eventually happen.
I waffled about stripping the forced conversion when !force_conv
vs. skipping them in iterative_hash_template_arg and
template_args_equal (like we already do for some other conversions) and
decided to go with the former, but that isn't a strong preference if it
turns out to be somehow problematic.
PR c++/112632
PR c++/112594
PR c++/111357
PR c++/104594
PR c++/67898
gcc/cp/ChangeLog:
* cp-tree.h (IMPLICIT_CONV_EXPR_FORCED): New.
* pt.cc (expand_integer_pack): Remove 111357 workaround.
(maybe_convert_nontype_argument): Add force parm.
(convert_template_argument): Handle alias template args
specially.
(tsubst_expr): Don't ignore IMPLICIT_CONV_EXPR_NONTYPE_ARG.
* error.cc (dump_expr) [CASE_CONVERT]: Handle null optype.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/alias-decl-nontype1.C: New test.
* g++.dg/cpp2a/concepts-narrowing1.C: New test.
* g++.dg/cpp2a/nontype-class63.C: New test.
* g++.dg/cpp2a/nontype-class63a.C: New test.
---
gcc/cp/cp-tree.h | 5 ++
gcc/cp/error.cc | 4 +-
gcc/cp/pt.cc | 48 +++++++++++++------
.../g++.dg/cpp0x/alias-decl-nontype1.C | 9 ++++
.../g++.dg/cpp2a/concepts-narrowing1.C | 16 +++++++
gcc/testsuite/g++.dg/cpp2a/nontype-class63.C | 24 ++++++++++
gcc/testsuite/g++.dg/cpp2a/nontype-class63a.C | 24 ++++++++++
7 files changed, 114 insertions(+), 16 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype1.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-narrowing1.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class63.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class63a.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index d9b14d7c4f5..60e6dafc549 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4717,6 +4717,11 @@ get_vec_init_expr (tree t)
#define IMPLICIT_CONV_EXPR_BRACED_INIT(NODE) \
(TREE_LANG_FLAG_2 (IMPLICIT_CONV_EXPR_CHECK (NODE)))
+/* True if NODE represents a conversion forced to be represented in
+ maybe_convert_nontype_argument, i.e. for an alias template. */
+#define IMPLICIT_CONV_EXPR_FORCED(NODE) \
+ (TREE_LANG_FLAG_3 (IMPLICIT_CONV_EXPR_CHECK (NODE)))
+
/* Nonzero means that an object of this type cannot be initialized using
an initializer list. */
#define CLASSTYPE_NON_AGGREGATE(NODE) \
diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index 52e24fb086c..d3fcac70ea1 100644
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -2673,6 +2673,8 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
tree ttype = TREE_TYPE (t);
tree optype = TREE_TYPE (op);
+ if (!optype)
+ optype = unknown_type_node;
if (TREE_CODE (ttype) != TREE_CODE (optype)
&& INDIRECT_TYPE_P (ttype)
@@ -2691,7 +2693,7 @@ dump_expr (cxx_pretty_printer *pp, tree t, int flags)
else
dump_unary_op (pp, "&", t, flags);
}
- else if (!same_type_p (TREE_TYPE (op), TREE_TYPE (t)))
+ else if (!same_type_p (optype, ttype))
{
/* It is a cast, but we cannot tell whether it is a
reinterpret or static cast. Use the C style notation. */
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index f82d018c981..fbbca469219 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -3760,13 +3760,6 @@ expand_integer_pack (tree call, tree args,
tsubst_flags_t complain,
{
if (hi != ohi)
{
- /* Work around maybe_convert_nontype_argument not doing this for
- dependent arguments. Don't use IMPLICIT_CONV_EXPR_NONTYPE_ARG
- because that will make tsubst_expr ignore it. */
- tree type = tsubst (TREE_TYPE (ohi), args, complain, in_decl);
- if (!TREE_TYPE (hi) || !same_type_p (type, TREE_TYPE (hi)))
- hi = build1 (IMPLICIT_CONV_EXPR, type, hi);
-
call = copy_node (call);
CALL_EXPR_ARG (call, 0) = hi;
}
@@ -8457,23 +8450,30 @@ convert_wildcard_argument (tree parm, tree arg)
conversion for the benefit of cp_tree_equal. */
static tree
-maybe_convert_nontype_argument (tree type, tree arg)
+maybe_convert_nontype_argument (tree type, tree arg, bool force)
{
/* Auto parms get no conversion. */
if (type_uses_auto (type))
return arg;
+ /* ??? Do we need to push the IMPLICIT_CONV_EXPR into the pack expansion?
+ That would complicate other things, and it doesn't seem necessary. */
+ if (TREE_CODE (arg) == EXPR_PACK_EXPANSION)
+ return arg;
/* We don't need or want to add this conversion now if we're going to use the
argument for deduction. */
- if (value_dependent_expression_p (arg))
+ if (!value_dependent_expression_p (arg))
+ force = false;
+ else if (!force)
return arg;
type = cv_unqualified (type);
tree argtype = TREE_TYPE (arg);
- if (same_type_p (type, argtype))
+ if (argtype && same_type_p (type, argtype))
return arg;
arg = build1 (IMPLICIT_CONV_EXPR, type, arg);
IMPLICIT_CONV_EXPR_NONTYPE_ARG (arg) = true;
+ IMPLICIT_CONV_EXPR_FORCED (arg) = force;
return arg;
}
@@ -8741,6 +8741,22 @@ convert_template_argument (tree parm,
if (t != TREE_TYPE (parm))
t = canonicalize_type_argument (t, complain);
+ /* We need to handle arguments for alias or concept templates
+ differently: we need to force building an IMPLICIT_CONV_EXPR, because
+ these arguments are going to be substituted directly into the
+ dependent type; they might not get another chance at
+ convert_nontype_argument. But if the argument ends up here again for
+ a template that isn't one of those, remove the conversion for
+ consistency between naming the same dependent type directly or through
+ an alias. */
+ bool force_conv = in_decl && (DECL_ALIAS_TEMPLATE_P (in_decl)
+ || concept_definition_p (in_decl));
+ if (!force_conv
+ && TREE_CODE (orig_arg) == IMPLICIT_CONV_EXPR
+ && IMPLICIT_CONV_EXPR_FORCED (orig_arg)
+ && same_type_p (TREE_TYPE (orig_arg), t))
+ orig_arg = TREE_OPERAND (orig_arg, 0);
+
if (!type_dependent_expression_p (orig_arg)
&& !uses_template_parms (t))
/* We used to call digest_init here. However, digest_init
@@ -8757,10 +8773,9 @@ convert_template_argument (tree parm,
else
{
val = canonicalize_expr_argument (orig_arg, complain);
- val = maybe_convert_nontype_argument (t, val);
+ val = maybe_convert_nontype_argument (t, val, force_conv);
}
-
if (val == NULL_TREE)
val = error_mark_node;
else if (val == error_mark_node && (complain & tf_error))
@@ -20056,9 +20071,12 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
RETURN (retval);
}
if (IMPLICIT_CONV_EXPR_NONTYPE_ARG (t))
- /* We'll pass this to convert_nontype_argument again, we don't need
- to actually perform any conversion here. */
- RETURN (expr);
+ {
+ tree r = convert_nontype_argument (type, expr, complain);
+ if (r == NULL_TREE)
+ r = error_mark_node;
+ RETURN (r);
+ }
int flags = LOOKUP_IMPLICIT;
if (IMPLICIT_CONV_EXPR_DIRECT_INIT (t))
flags = LOOKUP_NORMAL;
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype1.C
b/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype1.C
new file mode 100644
index 00000000000..3a9f0de834e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-nontype1.C
@@ -0,0 +1,9 @@
+// PR c++/67898
+// { dg-do compile { target c++11 } }
+
+template<class T, T V, class = decltype(V)> struct A;
+template<class U> using B = A<U, 0>;
+
+using type = A<bool, 0>;
+using type = B<bool>; // incorrectly resolves to A<bool, 0, int>
+ // instead of A<bool, 0, bool>
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-narrowing1.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-narrowing1.C
new file mode 100644
index 00000000000..dcfe2729f70
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-narrowing1.C
@@ -0,0 +1,16 @@
+// PR c++/104594
+// { dg-do compile { target c++20 } }
+
+template <unsigned char DIM_FROM>
+concept Geometry = (DIM_FROM == -1);
+
+template <class INIT>
+requires Geometry<INIT::n>
+auto GaussNewton(const INIT& init) -> void {}
+
+template<int N>
+struct X {
+ static constexpr int n = N;
+};
+
+int main() { GaussNewton(X<-1>{}); } // { dg-error "no match|narrowing" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class63.C
b/gcc/testsuite/g++.dg/cpp2a/nontype-class63.C
new file mode 100644
index 00000000000..2e617396912
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class63.C
@@ -0,0 +1,24 @@
+// PR c++/112632
+// { dg-do compile { target c++20 } }
+
+template<typename T>
+inline constexpr bool C = true;
+
+struct n {
+ constexpr n(int a) : i(a) {}
+ int i;
+};
+
+template<n N>
+using get_n_i_type = decltype(N.i);
+
+template<int X>
+int f() {
+ using iii = get_n_i_type<X>;
+#if 1 // Change to 0 and this compiles
+ static_assert(C<iii>);
+#endif
+ return iii{};
+}
+
+template int f<3>();
diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class63a.C
b/gcc/testsuite/g++.dg/cpp2a/nontype-class63a.C
new file mode 100644
index 00000000000..489a90d9fdb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class63a.C
@@ -0,0 +1,24 @@
+// PR c++/112594
+// { dg-do compile { target c++20 } }
+
+template<typename T>
+concept C = true;
+
+struct n {
+ constexpr n(int) {}
+ static int i;
+};
+
+template<n N>
+using get_n_i_type = decltype(N.i);
+
+template<int X>
+int f() {
+ using iii = get_n_i_type<X>;
+#if 1 // Change to 0 and this compiles
+ static_assert(C<iii>);
+#endif
+ return iii{};
+}
+
+template int f<3>();
base-commit: e04376b336502016456eaf4e90c3ea792c77c8df
--
2.39.3
