From d54ce4641ed106666208be36fd514cae8ff1153c Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Tue, 8 Mar 2022 13:55:15 -0500
Subject: [PATCH] c++: Wrong error with alias template in class tmpl [PR104108]
In r10-6329 I tried to optimize the number of calls to v_d_e_p in
convert_nontype_argument by remembering whether the expression was
value-dependent in a bool flag. I did that wrongly assuming that its
value-dependence will not be changed by build_converted_constant_expr.
This testcase shows that it can: b_c_c_e gets a VAR_DECL for m_parameter,
which is not value-dependent, but we're converting it to "const int &"
so it returns
(const int &)(const int *) &m_parameter
which suddenly becomes value-dependent because of the added ADDR_EXPR:
has_value_dependent_address is now true because m_parameter's context S<T>
is dependent. With this bug in place, we went to the second branch here:
if (TYPE_REF_OBJ_P (TREE_TYPE (expr)) && val_dep_p)
/* OK, dependent reference. We don't want to ask whether a DECL is
itself value-dependent, since what we want here is its address. */;
else
{
expr = build_address (expr);
if (invalid_tparm_referent_p (type, expr, complain))
return NULL_TREE;
}
wherein build_address created a bad tree and then i_t_r_p complained.
PR c++/104108
gcc/cp/ChangeLog:
* pt.cc (convert_nontype_argument): Recompute
value_dependent_expression_p after build_converted_constant_expr.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/alias-decl-74.C: New test.
---
gcc/cp/pt.cc | 4 +++-
gcc/testsuite/g++.dg/cpp0x/alias-decl-74.C | 9 +++++++++
2 files changed, 12 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/alias-decl-74.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index c350ebb0a799..d47483dd4f20 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -7316,7 +7316,7 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
if (non_dep)
expr = instantiate_non_dependent_expr_internal (expr, complain);
- const bool val_dep_p = value_dependent_expression_p (expr);
+ bool val_dep_p = value_dependent_expression_p (expr);
if (val_dep_p)
expr = canonicalize_expr_argument (expr, complain);
else
@@ -7357,6 +7357,8 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
expr = maybe_constant_value (expr, NULL_TREE,
/*manifestly_const_eval=*/true);
expr = convert_from_reference (expr);
+ /* EXPR may have become value-dependent. */
+ val_dep_p = value_dependent_expression_p (expr);
}
else if (TYPE_PTR_OR_PTRMEM_P (type))
{
diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-74.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-74.C
new file mode 100644
index 000000000000..8382d8563827
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-74.C
@@ -0,0 +1,9 @@
+// PR c++/104108
+// { dg-do compile { target c++11 } }
+
+template<template<const int&> class T>
+struct S {
+ static int m_parameter;
+ template<template<const int&> class TT>
+ using U = TT<m_parameter>;
+};
--
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