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* [gcc r9-9436] c++: Diagnose references to void in structured bindings [PR99650]
@ 2021-04-20 23:33 Jakub Jelinek
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From: Jakub Jelinek @ 2021-04-20 23:33 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:dd320787b4eb11521e3ae3f9aa9504b31ee08c36
commit r9-9436-gdd320787b4eb11521e3ae3f9aa9504b31ee08c36
Author: Jakub Jelinek <jakub@redhat.com>
Date: Tue Mar 23 10:23:42 2021 +0100
c++: Diagnose references to void in structured bindings [PR99650]
We ICE on the following testcase, because std::tuple_element<...,...>::type
is void and for structured bindings we therefore need to create
void & or void && which is invalid. We created such REFERENCE_TYPE and
later ICEd in the middle-end.
The following patch fixes it by diagnosing that.
2021-03-23 Jakub Jelinek <jakub@redhat.com>
PR c++/99650
* decl.c (cp_finish_decomp): Diagnose void initializers when
using tuple_element and get.
* g++.dg/cpp1z/decomp55.C: New test.
(cherry picked from commit d5e379e3fe19362442b5d0ac608fb8ddf67fecd3)
Diff:
---
gcc/cp/decl.c | 6 ++++++
gcc/testsuite/g++.dg/cpp1z/decomp55.C | 19 +++++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 1b20d13e4b3..782f0f6e60f 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -7842,6 +7842,12 @@ cp_finish_decomp (tree decl, tree first, unsigned int count)
: get_tuple_element_type (type, i));
input_location = sloc;
+ if (VOID_TYPE_P (eltype))
+ {
+ error ("%<std::tuple_element<%u, %T>::type%> is %<void%>",
+ i, type);
+ eltype = error_mark_node;
+ }
if (init == error_mark_node || eltype == error_mark_node)
{
inform (dloc, "in initialization of structured binding "
diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp55.C b/gcc/testsuite/g++.dg/cpp1z/decomp55.C
new file mode 100644
index 00000000000..bb4bf754abb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp55.C
@@ -0,0 +1,19 @@
+// PR c++/99650
+// { dg-do compile { target c++17 } }
+
+namespace std {
+ template<typename T> struct tuple_size;
+ template<int, typename> struct tuple_element;
+}
+
+struct A {
+ int i;
+ template <int I> void get() { }
+};
+
+template<> struct std::tuple_size<A> { static const int value = 2; };
+template<int I> struct std::tuple_element<I,A> { using type = void; };
+
+A a = { 42 };
+auto [ x, y ] = a; // { dg-error ".std::tuple_element<0, A>::type. is .void." }
+// { dg-message "in initialization of structured binding variable 'x'" "" { target *-*-* } .-1 }
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