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| author | Jakub Jelinek <jakub@redhat.com> | 2021-03-23 10:23:42 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-03-23 10:23:42 +0100 |
| commit | 3e07e7a6a7f34f0ec2f1a3e50ebc52b77de11a30 (patch) | |
| tree | 9de1e3a2da95fe61d4939efd2fba0bfa1813a0e4 | |
| parent | a28cc94a27529b3108ea85be9ef5557a3c95791d (diff) | |
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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.
| -rw-r--r-- | gcc/cp/decl.c | 6 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp1z/decomp55.C | 19 |
2 files changed, 25 insertions, 0 deletions
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 8e8f37d..b1d8e44 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -8629,6 +8629,12 @@ 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 0000000..bb4bf75 --- /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 } |