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* [gcc r13-4138] c++: Implement CWG2635 - Constrained structured bindings
@ 2022-11-18 8:05 Jakub Jelinek
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From: Jakub Jelinek @ 2022-11-18 8:05 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:e5049dfbe294abc56953d4f0b412000cd8a1f39e
commit r13-4138-ge5049dfbe294abc56953d4f0b412000cd8a1f39e
Author: Jakub Jelinek <jakub@redhat.com>
Date: Fri Nov 18 09:04:16 2022 +0100
c++: Implement CWG2635 - Constrained structured bindings
The following patch implements CWG2635.
2022-11-18 Jakub Jelinek <jakub@redhat.com>
* decl.cc (grokdeclarator): Implement
CWG2635 - Constrained structured bindings. Emit a pedwarn on
constrained auto type. Add auto_diagnostic_group for error_at
and inform for non-auto type on structured bindings declaration.
* g++.dg/cpp2a/decomp5.C: New test.
* g++.dg/cpp2a/decomp6.C: New test.
* g++.dg/cpp2a/decomp7.C: New test.
* g++.dg/cpp2a/concepts-placeholder7.C: Adjust expected diagnostics.
* g++.dg/cpp2a/concepts-placeholder8.C: Likewise.
* g++.dg/cpp2a/concepts-placeholder9.C: New test.
* g++.dg/cpp2a/concepts-placeholder10.C: New test.
Diff:
---
gcc/cp/decl.cc | 5 ++++
.../g++.dg/cpp2a/concepts-placeholder10.C | 11 ++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-placeholder7.C | 12 ++++----
gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C | 5 ++--
gcc/testsuite/g++.dg/cpp2a/concepts-placeholder9.C | 33 ++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/decomp5.C | 19 +++++++++++++
gcc/testsuite/g++.dg/cpp2a/decomp6.C | 20 +++++++++++++
gcc/testsuite/g++.dg/cpp2a/decomp7.C | 20 +++++++++++++
8 files changed, 118 insertions(+), 7 deletions(-)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 9a7b1a6c381..341b4bba992 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -12664,6 +12664,7 @@ grokdeclarator (const cp_declarator *declarator,
{
if (type != error_mark_node)
{
+ auto_diagnostic_group d;
error_at (loc, "structured binding declaration cannot have "
"type %qT", type);
inform (loc,
@@ -12673,6 +12674,10 @@ grokdeclarator (const cp_declarator *declarator,
type = build_qualified_type (make_auto (), type_quals);
declspecs->type = type;
}
+ else if (PLACEHOLDER_TYPE_CONSTRAINTS_INFO (type))
+ pedwarn (loc, OPT_Wpedantic,
+ "structured binding declaration cannot have constrained "
+ "%<auto%> type %qT", type);
inlinep = 0;
typedef_p = 0;
constexpr_p = 0;
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder10.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder10.C
new file mode 100644
index 00000000000..b831531b113
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder10.C
@@ -0,0 +1,11 @@
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wno-pedantic" }
+
+template <class T> concept is_const = __is_same(T, const T);
+
+void f() {
+ int x[] = {1,2};
+ const int y[] = {3};
+ const is_const auto [a,b] = x; // { dg-error "constraints" }
+ const is_const auto [c] = y;
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder7.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder7.C
index 93219ff4f05..7ba6ab942b5 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder7.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder7.C
@@ -7,16 +7,18 @@ template <class>
void f() {
int x[] = {1,2};
int y[] = {3};
- C1 auto [a,b] = x;
- C1 auto [c] = y; // { dg-error "constraints" }
+ C1 auto [a,b] = x; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C1<<placeholder>, >\\\]'" }
+ C1 auto [c] = y; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C1<<placeholder>, >\\\]'" }
+ // { dg-error "constraints" "" { target *-*-* } .-1 }
}
template <class T>
void g() {
T x[] = {1,2};
T y[] = {3};
- C1 auto [a,b] = x;
- C1 auto [c] = y; // { dg-error "constraints" }
+ C1 auto [a,b] = x; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C1<<placeholder>, >\\\]'" }
+ C1 auto [c] = y; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C1<<placeholder>, >\\\]'" }
+ // { dg-error "constraints" "" { target *-*-* } .-1 }
}
template void g<int>();
@@ -27,6 +29,6 @@ struct S { int a, b; } s;
template <class T>
void h() {
- const C2<T> auto& [a, b] = s;
+ const C2<T> auto& [a, b] = s; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'const auto \\\[requires ::C2<<placeholder>, >\\\]'" }
}
template void h<int>();
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C
index e78659203ba..d887961227f 100644
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder8.C
@@ -5,6 +5,7 @@ template <class T> concept is_const = __is_same(T, const T);
void f() {
int x[] = {1,2};
const int y[] = {3};
- const is_const auto [a,b] = x; // { dg-error "constraints" }
- const is_const auto [c] = y;
+ const is_const auto [a,b] = x; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'const auto \\\[requires ::is_const<<placeholder>, >\\\]'" }
+ // { dg-error "constraints" "" { target *-*-* } .-1 }
+ const is_const auto [c] = y; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'const auto \\\[requires ::is_const<<placeholder>, >\\\]'" }
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder9.C b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder9.C
new file mode 100644
index 00000000000..96732f39756
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-placeholder9.C
@@ -0,0 +1,33 @@
+// PR c++/99899
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wno-pedantic" }
+
+template <class T> concept C1 = sizeof(T) > sizeof(int[1]);
+
+template <class>
+void f() {
+ int x[] = {1,2};
+ int y[] = {3};
+ C1 auto [a,b] = x;
+ C1 auto [c] = y; // { dg-error "constraints" }
+}
+
+template <class T>
+void g() {
+ T x[] = {1,2};
+ T y[] = {3};
+ C1 auto [a,b] = x;
+ C1 auto [c] = y; // { dg-error "constraints" }
+}
+template void g<int>();
+
+
+template <class... Ts> concept C2 = sizeof...(Ts) > 1;
+
+struct S { int a, b; } s;
+
+template <class T>
+void h() {
+ const C2<T> auto& [a, b] = s;
+}
+template void h<int>();
diff --git a/gcc/testsuite/g++.dg/cpp2a/decomp5.C b/gcc/testsuite/g++.dg/cpp2a/decomp5.C
new file mode 100644
index 00000000000..9ea31c6b87b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/decomp5.C
@@ -0,0 +1,19 @@
+// CWG2635 - Constrained structured bindings
+// { dg-do compile { target c++20 } }
+
+namespace std {
+ template<typename T> struct tuple_size;
+ template<int, typename> struct tuple_element;
+}
+
+struct A {
+ int i;
+ A(int x) : i(x) {}
+ template <int I> int& get() { return i; }
+};
+
+template<> struct std::tuple_size<A> { static const int value = 2; };
+template<int I> struct std::tuple_element<I,A> { using type = int; };
+
+template<class T> concept C = true;
+C auto [x, y] = A{1}; // { dg-error "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C<<placeholder>, >\\\]'" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/decomp6.C b/gcc/testsuite/g++.dg/cpp2a/decomp6.C
new file mode 100644
index 00000000000..e6cd034ca35
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/decomp6.C
@@ -0,0 +1,20 @@
+// CWG2635 - Constrained structured bindings
+// { dg-do compile { target c++20 } }
+// { dg-options "-pedantic" }
+
+namespace std {
+ template<typename T> struct tuple_size;
+ template<int, typename> struct tuple_element;
+}
+
+struct A {
+ int i;
+ A(int x) : i(x) {}
+ template <int I> int& get() { return i; }
+};
+
+template<> struct std::tuple_size<A> { static const int value = 2; };
+template<int I> struct std::tuple_element<I,A> { using type = int; };
+
+template<class T> concept C = true;
+C auto [x, y] = A{1}; // { dg-warning "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C<<placeholder>, >\\\]'" }
diff --git a/gcc/testsuite/g++.dg/cpp2a/decomp7.C b/gcc/testsuite/g++.dg/cpp2a/decomp7.C
new file mode 100644
index 00000000000..581797e2d44
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/decomp7.C
@@ -0,0 +1,20 @@
+// CWG2635 - Constrained structured bindings
+// { dg-do compile { target c++20 } }
+// { dg-options "-Wno-pedantic" }
+
+namespace std {
+ template<typename T> struct tuple_size;
+ template<int, typename> struct tuple_element;
+}
+
+struct A {
+ int i;
+ A(int x) : i(x) {}
+ template <int I> int& get() { return i; }
+};
+
+template<> struct std::tuple_size<A> { static const int value = 2; };
+template<int I> struct std::tuple_element<I,A> { using type = int; };
+
+template<class T> concept C = true;
+C auto [x, y] = A{1}; // { dg-bogus "structured binding declaration cannot have constrained 'auto' type 'auto \\\[requires ::C<<placeholder>, >\\\]'" }
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