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* [gcc r12-5860] c++: Handle auto(x) in parameter-declaration-clause [PR103401]
@ 2021-12-09 16:49 Marek Polacek
0 siblings, 0 replies; only message in thread
From: Marek Polacek @ 2021-12-09 16:49 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:6a071b2d40a1078b4029c2b77ef29ffca4e7050c
commit r12-5860-g6a071b2d40a1078b4029c2b77ef29ffca4e7050c
Author: Marek Polacek <polacek@redhat.com>
Date: Thu Nov 25 09:08:03 2021 -0500
c++: Handle auto(x) in parameter-declaration-clause [PR103401]
In C++23, auto(x) is valid, so decltype(auto(x)) should also be valid,
so
void f(decltype(auto(0)));
should be just as
void f(int);
but currently, everytime we see 'auto' in a parameter-declaration-clause,
we try to synthesize_implicit_template_parm for it, creating a new template
parameter list. The code above actually has us calling s_i_t_p twice;
once from cp_parser_decltype_expr -> cp_parser_postfix_expression which
fails and then again from cp_parser_decltype_expr -> cp_parser_expression.
So it looks like we have f<auto, auto> and we accept ill-formed code.
This shows that we need to be more careful about synthesizing the
implicit template parameter. [dcl.spec.auto.general] says that "A
placeholder-type-specifier of the form type-constraintopt auto can be
used as a decl-specifier of the decl-specifier-seq of a
parameter-declaration of a function declaration or lambda-expression..."
so this patch turns off auto_is_... after we've parsed the decl-specifier-seq.
That doesn't quite cut it yet though, because we also need to handle an
auto nested in the decl-specifier:
void f(decltype(new auto{0}));
therefore the cp_parser_decltype change.
To accept "sizeof(auto{10})", the cp_parser_type_id_1 hunk only gives a
hard error when we're not parsing tentatively.
The cp_parser_parameter_declaration hunk broke lambda-generic-85713-2.C but
I think the error we issue with this patch is in fact correct, and clang++
agrees.
The r11-1913 change is OK: we need to make sure that we see '(auto)' after
decltype to go ahead with 'decltype(auto)'.
PR c++/103401
gcc/cp/ChangeLog:
* parser.c (cp_parser_decltype): Clear
auto_is_implicit_function_template_parm_p.
(cp_parser_type_id_1): Give errors only when !cp_parser_simulate_error.
(cp_parser_parameter_declaration): Clear
auto_is_implicit_function_template_parm_p after parsing the
decl-specifier-seq.
(cp_parser_sizeof_operand): Clear
auto_is_implicit_function_template_parm_p.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/lambda-generic-85713-2.C: Add dg-error.
* g++.dg/cpp1y/pr60054.C: Adjust dg-error.
* g++.dg/cpp1y/pr60332.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-2.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979-3.C: Likewise.
* g++.dg/cpp2a/concepts-pr84979.C: Likewise.
* g++.dg/cpp23/auto-fncast7.C: New test.
* g++.dg/cpp23/auto-fncast8.C: New test.
* g++.dg/cpp23/auto-fncast9.C: New test.
Diff:
---
gcc/cp/parser.c | 38 +++++++++++++++-----
.../g++.dg/cpp1y/lambda-generic-85713-2.C | 2 +-
gcc/testsuite/g++.dg/cpp1y/pr60054.C | 4 +--
gcc/testsuite/g++.dg/cpp1y/pr60332.C | 3 +-
gcc/testsuite/g++.dg/cpp23/auto-fncast7.C | 9 +++++
gcc/testsuite/g++.dg/cpp23/auto-fncast8.C | 42 ++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp23/auto-fncast9.C | 17 +++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C | 12 +++----
gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C | 12 +++----
gcc/testsuite/g++.dg/cpp2a/concepts-pr84979.C | 2 +-
10 files changed, 116 insertions(+), 25 deletions(-)
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 6f273bfe21f..de464afdb54 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -16432,6 +16432,16 @@ cp_parser_decltype (cp_parser *parser)
= parser->greater_than_is_operator_p;
parser->greater_than_is_operator_p = true;
+ /* Don't synthesize an implicit template type parameter here. This
+ could happen with C++23 code like
+
+ void f(decltype(new auto{0}));
+
+ where we want to deduce the auto right away so that the parameter
+ is of type 'int *'. */
+ auto cleanup = make_temp_override
+ (parser->auto_is_implicit_function_template_parm_p, false);
+
/* Do not actually evaluate the expression. */
++cp_unevaluated_operand;
@@ -24144,22 +24154,22 @@ cp_parser_type_id_1 (cp_parser *parser, cp_parser_flags flags,
/* OK */;
else
{
- location_t loc = type_specifier_seq.locations[ds_type_spec];
- if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node))
+ if (!cp_parser_simulate_error (parser))
{
- if (!cp_parser_simulate_error (parser))
+ location_t loc = type_specifier_seq.locations[ds_type_spec];
+ if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node))
{
error_at (loc, "missing template arguments after %qT",
auto_node);
inform (DECL_SOURCE_LOCATION (tmpl), "%qD declared here",
tmpl);
}
+ else if (parser->in_template_argument_list_p)
+ error_at (loc, "%qT not permitted in template argument",
+ auto_node);
+ else
+ error_at (loc, "invalid use of %qT", auto_node);
}
- else if (parser->in_template_argument_list_p)
- error_at (loc, "%qT not permitted in template argument",
- auto_node);
- else
- error_at (loc, "invalid use of %qT", auto_node);
return error_mark_node;
}
}
@@ -24668,6 +24678,15 @@ cp_parser_parameter_declaration (cp_parser *parser,
&decl_specifiers,
&declares_class_or_enum);
+ /* [dcl.spec.auto.general]: "A placeholder-type-specifier of the form
+ type-constraint opt auto can be used as a decl-specifier of the
+ decl-specifier-seq of a parameter-declaration of a function declaration
+ or lambda-expression..." but we must not synthesize an implicit template
+ type parameter in its declarator. That is, in "void f(auto[auto{10}]);"
+ we want to synthesize only the first auto. */
+ auto cleanup = make_temp_override
+ (parser->auto_is_implicit_function_template_parm_p, false);
+
/* Complain about missing 'typename' or other invalid type names. */
if (!decl_specifiers.any_type_specifiers_p
&& cp_parser_parse_and_diagnose_invalid_type_name (parser))
@@ -32369,6 +32388,9 @@ cp_parser_sizeof_operand (cp_parser* parser, enum rid keyword)
= parser->non_integral_constant_expression_p;
parser->integral_constant_expression_p = false;
+ auto cleanup = make_temp_override
+ (parser->auto_is_implicit_function_template_parm_p, false);
+
/* Do not actually evaluate the expression. */
++cp_unevaluated_operand;
++c_inhibit_evaluation_warnings;
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-85713-2.C b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-85713-2.C
index 8fb8dfdeaf0..dbc9e8c732c 100644
--- a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-85713-2.C
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-85713-2.C
@@ -2,6 +2,6 @@
// { dg-do compile { target c++14 } }
auto l4 = [](auto v, auto (&array (int)) [5]) -> int { return v + array[0]; };
-auto l5 = [](auto v, auto (&array (auto)) [5]) -> int { return v + array[0]; };
+auto l5 = [](auto v, auto (&array (auto)) [5]) -> int { return v + array[0]; }; // { dg-error ".auto. parameter not permitted in this context" }
auto l6 = [](auto v, auto (&array (int int)) [5]) -> int { return v + array[0]; }; // { dg-error "two or more data types" }
auto l7 = [](auto v, auto (&array (int auto)) [5]) -> int { return v + array[0]; }; // { dg-error "two or more data types" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr60054.C b/gcc/testsuite/g++.dg/cpp1y/pr60054.C
index f51120f6425..0d4925afbf2 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr60054.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr60054.C
@@ -6,6 +6,6 @@ template<typename T> decltype(T{}) fooB(T);
void bar()
{
- fooA((auto*)0); // { dg-error "invalid use" }
- fooB((auto*)0); // { dg-error "invalid use" }
+ fooA((auto*)0); // { dg-error "expected" }
+ fooB((auto*)0); // { dg-error "expected" }
}
diff --git a/gcc/testsuite/g++.dg/cpp1y/pr60332.C b/gcc/testsuite/g++.dg/cpp1y/pr60332.C
index e75ab8584e3..f3a7980b380 100644
--- a/gcc/testsuite/g++.dg/cpp1y/pr60332.C
+++ b/gcc/testsuite/g++.dg/cpp1y/pr60332.C
@@ -3,4 +3,5 @@
void foo();
-auto f = (auto(*)())(&foo); // { dg-error "invalid" }
+auto f = (auto(*)())(&foo); // { dg-error "expected" }
+// { dg-error "only available" "" { target c++20_down } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast7.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast7.C
new file mode 100644
index 00000000000..763164f3e5b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast7.C
@@ -0,0 +1,9 @@
+// PR c++/103401
+// { dg-do compile { target c++23 } }
+
+void f(decltype(auto(0))) { }
+
+int main()
+{
+ f<int,int>(0); // { dg-error "no matching function" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast8.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast8.C
new file mode 100644
index 00000000000..9fb7b9c2516
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast8.C
@@ -0,0 +1,42 @@
+// PR c++/103401
+// { dg-do compile { target c++23 } }
+
+void f1 (decltype(auto(0)));
+void f2 (decltype(auto{0}));
+void f3 (int = auto(42));
+void f4 (int = auto{42});
+void f5 (decltype(auto(0)) = auto(42));
+void f6 (auto (x));
+void f7 (int[auto(10)]);
+void f8 (int[auto{10}]);
+void f9 (auto[auto{10}]);
+void f10 (auto);
+void f11 (int x, decltype(x) y);
+void f12 (int[sizeof(auto{10})]);
+void f13 (int[sizeof(auto(10))]);
+void f14 (int[__extension__ alignof(auto{10})]);
+void f15 (int[__extension__ alignof(auto(10))]);
+
+void
+g ()
+{
+ int a[2];
+ f1 (1);
+ f2 (1);
+ f3 ();
+ f3 (1);
+ f4 ();
+ f4 (1);
+ f5 ();
+ f5 (1);
+ f6 ('a');
+ f7 (&a[0]);
+ f8 (&a[0]);
+ f9 (&a[0]);
+ f10 (1);
+ f11 (1, 2);
+ f12 (&a[0]);
+ f13 (&a[0]);
+ f14 (&a[0]);
+ f15 (&a[0]);
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast9.C b/gcc/testsuite/g++.dg/cpp23/auto-fncast9.C
new file mode 100644
index 00000000000..12a0dcece75
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast9.C
@@ -0,0 +1,17 @@
+// PR c++/103401
+// { dg-do compile { target c++23 } }
+
+void f1(decltype(new auto{0}));
+void f2(decltype(new int{0}));
+
+void
+g ()
+{
+ int i;
+ void f3(decltype(new auto{0}));
+ void f4(decltype(new int{0}));
+ f1 (&i);
+ f2 (&i);
+ f3 (&i);
+ f4 (&i);
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
index 025bbf3bb93..75f8e40ca58 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-2.C
@@ -4,9 +4,9 @@
template <typename T>
void foo1(T& t) {
typename T::template C<void> tcv = t;
- typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
- T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted|unable" }
+ typename T::template C<auto> u = tcv; // { dg-error "" "" { target c++20 } }
+ T::template C<auto>::f (tcv, u); // { dg-error "" }
+ (typename T::template D<auto> (t)); // { dg-error "" }
// { dg-warning "only available" "" { target c++17_down } .-1 }
}
@@ -23,9 +23,9 @@ struct T1 {
template <typename T>
void foo2(T& t) {
typename T::template C<void> tcv = t;
- typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
- T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- T::template D<auto> (t); // { dg-error "invalid|not permitted" }
+ typename T::template C<auto> u = tcv; // { dg-error "" "" { target c++20 } }
+ T::template C<auto>::f (tcv, u); // { dg-error "" }
+ T::template D<auto> (t); // { dg-error "" }
}
struct T2 {
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
index 80a388462eb..1c1a41c0fa2 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979-3.C
@@ -8,9 +8,9 @@
template <typename T>
void foo1(T& t) {
typename T::template C<void> tcv = t;
- typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
- T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- (typename T::template D<auto> (t)); // { dg-error "invalid|not permitted|no class" }
+ typename T::template C<auto> u = tcv; // { dg-error "" "" { target c++20 } }
+ T::template C<auto>::f (tcv, u); // { dg-error "" }
+ (typename T::template D<auto> (t)); // { dg-error "" }
// { dg-warning "only available" "" { target c++17_down } .-1 }
}
@@ -27,9 +27,9 @@ struct T1 {
template <typename T>
void foo2(T& t) {
typename T::template C<void> tcv = t;
- typename T::template C<auto> u = tcv; // { dg-error "not permitted" "" { target c++20 } }
- T::template C<auto>::f (tcv, u); // { dg-error "incomplete|not permitted" }
- T::template D<auto> (t); // { dg-error "yields a type|not permitted" }
+ typename T::template C<auto> u = tcv; // { dg-error "" "" { target c++20 } }
+ T::template C<auto>::f (tcv, u); // { dg-error "" }
+ T::template D<auto> (t); // { dg-error "" }
}
struct T2 {
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979.C
index 81555eb4554..a83601527bb 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr84979.C
@@ -5,5 +5,5 @@ template<typename> void foo() {}
void bar()
{
- foo<auto>(); // { dg-error "not permitted|invalid|no matching function" }
+ foo<auto>(); // { dg-error "" }
}
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