The problem here is that some code paths are not prepared to handle a
non-dependent PAREN_EXPR, which my fix for PR c++/70106 introduced. In
particular lvalue_kind() returns clk_none for a PAREN_EXPR which makes
build_x_unary_op() emit a bogus error for an expression like &(A::b).
(If the PAREN_EXPR were dependent then lvalue_kind() wouldn't get called
in the first place, build_x_unary_op() would exit early.)
This patch replaces the 70106 fix. Instead of wrapping a SCOPE_REF in a
PAREN_EXPR, this patch overloads the REF_PARENTHESIZED_P to apply to
SCOPE_REFs too. This makes sense to me because the two tree codes are
closely related (e.g. a SCOPE_REF before instantiation may become a
COMPONENT_REF after instantiation) so they should be treated similarly
by force_paren_expr().
There are two rather simpler ways to fix this PR. One is to make
lvalue_kind() recurse into PAREN_EXPRs (although other parts of the FE
may be mishandling non-dependent PAREN_EXPRs as well), and the other is
to make force_paren_expr() never return a non-dependent PAREN_EXPR,
which can be achieved by building the PAREN_EXPR with build_nt(). I am
not sure which approach is best for GCC 7 and for GCC 6.
Somewhat unrelated the fix: I couldn't find an existing test that
checked that force_paren_expr handles SCOPE_REFs properly wrt auto
deduction so I added one.
Bootstrap and regtesting in progress on x86_64-pc-linux-gnu.
gcc/cp/ChangeLog:
PR c++/70822
PR c++/70106
* cp-tree.h (REF_PARENTHESIZED_P): Make this flag apply to
SCOPE_REFs too.
* pt.c (tsubst_qualified_id): If REF_PARENTHESIZED_P is set
on the qualified_id then propagate it to the resulting
expression.
(do_auto_deduction): Check REF_PARENTHESIZED_P on SCOPE_REFs
too.
* semantics.c (force_paren_expr): If given a SCOPE_REF, just set
its REF_PARENTHESIZED_P flag.
gcc/testsuite/ChangeLog:
PR c++/70822
PR c++/70106
* g++.dg/cpp1y/auto-fn31.C: New test.
* g++.dg/cpp1y/paren4.C: New test.
---
gcc/cp/cp-tree.h | 4 ++--
gcc/cp/pt.c | 15 +++++++++++----
gcc/cp/semantics.c | 13 +++----------
gcc/testsuite/g++.dg/cpp1y/auto-fn31.C | 33 +++++++++++++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp1y/paren4.C | 14 ++++++++++++++
5 files changed, 63 insertions(+), 16 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/auto-fn31.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/paren4.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 2caf7ce..0df5953 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -170,7 +170,7 @@ operator == (const cp_expr &lhs, tree rhs)
TARGET_EXPR_DIRECT_INIT_P (in TARGET_EXPR)
FNDECL_USED_AUTO (in FUNCTION_DECL)
DECLTYPE_FOR_LAMBDA_PROXY (in DECLTYPE_TYPE)
- REF_PARENTHESIZED_P (in COMPONENT_REF, INDIRECT_REF)
+ REF_PARENTHESIZED_P (in COMPONENT_REF, INDIRECT_REF, SCOPE_REF)
AGGR_INIT_ZERO_FIRST (in AGGR_INIT_EXPR)
CONSTRUCTOR_MUTABLE_POISON (in CONSTRUCTOR)
3: (TREE_REFERENCE_EXPR) (in NON_LVALUE_EXPR) (commented-out).
@@ -3403,7 +3403,7 @@ extern void decl_shadowed_for_var_insert (tree, tree);
some of the time in C++14 mode. */
#define REF_PARENTHESIZED_P(NODE) \
- TREE_LANG_FLAG_2 (TREE_CHECK2 ((NODE), COMPONENT_REF, INDIRECT_REF))
+ TREE_LANG_FLAG_2 (TREE_CHECK3 ((NODE), COMPONENT_REF, INDIRECT_REF,
SCOPE_REF))
/* Nonzero if this AGGR_INIT_EXPR provides for initialization via a
constructor call, rather than an ordinary function call. */
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index e7ec629..7adf308 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -13741,8 +13741,10 @@ tsubst_qualified_id (tree qualified_id, tree args,
{
if (is_template)
expr = build_min_nt_loc (loc, TEMPLATE_ID_EXPR, expr, template_args);
- return build_qualified_name (NULL_TREE, scope, expr,
- QUALIFIED_NAME_IS_TEMPLATE (qualified_id));
+ tree r = build_qualified_name (NULL_TREE, scope, expr,
+ QUALIFIED_NAME_IS_TEMPLATE (qualified_id));
+ REF_PARENTHESIZED_P (r) = REF_PARENTHESIZED_P (qualified_id);
+ return r;
}
if (!BASELINK_P (name) && !DECL_P (expr))
@@ -13822,6 +13824,9 @@ tsubst_qualified_id (tree qualified_id, tree args,
&& TREE_CODE (expr) != OFFSET_REF)
expr = convert_from_reference (expr);
+ if (REF_PARENTHESIZED_P (qualified_id))
+ expr = force_paren_expr (expr);
+
return expr;
}
@@ -23966,8 +23971,10 @@ do_auto_deduction (tree type, tree init, tree
auto_node,
if (AUTO_IS_DECLTYPE (auto_node))
{
- bool id = (DECL_P (init) || (TREE_CODE (init) == COMPONENT_REF
- && !REF_PARENTHESIZED_P (init)));
+ bool id = (DECL_P (init)
+ || ((TREE_CODE (init) == COMPONENT_REF
+ || TREE_CODE (init) == SCOPE_REF)
+ && !REF_PARENTHESIZED_P (init)));
targs = make_tree_vec (1);
TREE_VEC_ELT (targs, 0)
= finish_decltype_type (init, id, tf_warning_or_error);
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index bb13fad..89da773 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -1647,17 +1647,10 @@ force_paren_expr (tree expr)
&& TREE_CODE (expr) != SCOPE_REF)
return expr;
- if (TREE_CODE (expr) == COMPONENT_REF)
+ if (TREE_CODE (expr) == COMPONENT_REF
+ || TREE_CODE (expr) == SCOPE_REF)
REF_PARENTHESIZED_P (expr) = true;
- else if (type_dependent_expression_p (expr)
- /* When processing_template_decl, a SCOPE_REF may actually be
- referring to a non-static data member of the current class, in
- which case its TREE_TYPE may not be properly cv-qualified (the
- cv-qualifiers of the implicit *this object haven't yet been taken
- into account) so we have to delay building a static_cast until
- instantiation. */
- || (processing_template_decl
- && TREE_CODE (expr) == SCOPE_REF))
+ else if (type_dependent_expression_p (expr))
expr = build1 (PAREN_EXPR, TREE_TYPE (expr), expr);
else if (VAR_P (expr) && DECL_HARD_REGISTER (expr))
/* We can't bind a hard register variable to a reference. */;
diff --git a/gcc/testsuite/g++.dg/cpp1y/auto-fn31.C
b/gcc/testsuite/g++.dg/cpp1y/auto-fn31.C
new file mode 100644
index 0000000..0a5dafc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/auto-fn31.C
@@ -0,0 +1,33 @@
+// { dg-do compile { target c++14 } }
+
+template<class,class> struct same_type;
+template<class T> struct same_type<T,T> {};
+
+struct A
+{
+ static int b;
+ int c;
+
+ template <int>
+ decltype(auto) f() { return A::c; }
+
+ template <int>
+ decltype(auto) g() { return (A::c); }
+};
+
+A a;
+
+template <int>
+decltype(auto) f() { return A::b; }
+
+template <int>
+decltype(auto) g() { return (A::b); }
+
+int main()
+{
+ same_type<decltype(f<0>()), int>();
+ same_type<decltype(g<0>()), int&>();
+
+ same_type<decltype(a.f<0>()), int>();
+ same_type<decltype(a.g<0>()), int&>();
+}
diff --git a/gcc/testsuite/g++.dg/cpp1y/paren4.C
b/gcc/testsuite/g++.dg/cpp1y/paren4.C
new file mode 100644
index 0000000..71abe84
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/paren4.C
@@ -0,0 +1,14 @@
+// PR c++/70822
+// { dg-do compile { target c++14 } }
+
+struct a
+{
+ static int b;
+};
+
+template <typename>
+void
+foo ()
+{
+ &(a::b);
+}
--
2.8.1.361.g2fbef4c
