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* [gcc r9-9416] c++: Fix ICE with structured binding initialized to incomplete array [PR97878]
@ 2021-04-20 23:32 Jakub Jelinek
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From: Jakub Jelinek @ 2021-04-20 23:32 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:5c85df8968b00acc934396d7461a4a5ac6ddedd1
commit r9-9416-g5c85df8968b00acc934396d7461a4a5ac6ddedd1
Author: Jakub Jelinek <jakub@redhat.com>
Date: Fri Feb 5 10:22:07 2021 +0100
c++: Fix ICE with structured binding initialized to incomplete array [PR97878]
We ICE on the following testcase, for incomplete array a on auto [b] { a }; without
giving any kind of diagnostics, with auto [c] = a; during error-recovery.
The problem is that we get too far through check_initializer and e.g.
store_init_value -> constexpr stuff can't deal with incomplete array types.
As the type of the structured binding artificial variable is always deduced,
I think it is easiest to diagnose this early, even if they have array types
we'll need their deduced type to be complete rather than just its element
type.
2021-02-05 Jakub Jelinek <jakub@redhat.com>
PR c++/97878
* decl.c (check_array_initializer): For structured bindings, require
the array type to be complete.
* g++.dg/cpp1z/decomp54.C: New test.
(cherry picked from commit 8b7f2d3eae16dd629ae7ae40bb76f4bb0099f441)
Diff:
---
gcc/cp/decl.c | 13 +++++++++++++
gcc/testsuite/g++.dg/cpp1z/decomp54.C | 17 +++++++++++++++++
2 files changed, 30 insertions(+)
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 3d51daeec30..7350212b8e7 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -6319,6 +6319,19 @@ check_array_initializer (tree decl, tree type, tree init)
{
tree element_type = TREE_TYPE (type);
+ /* Structured binding when initialized with an array type needs
+ to have complete type. */
+ if (decl
+ && DECL_DECOMPOSITION_P (decl)
+ && !DECL_DECOMP_BASE (decl)
+ && !COMPLETE_TYPE_P (type))
+ {
+ error_at (DECL_SOURCE_LOCATION (decl),
+ "structured binding has incomplete type %qT", type);
+ TREE_TYPE (decl) = error_mark_node;
+ return true;
+ }
+
/* The array type itself need not be complete, because the
initializer may tell us how many elements are in the array.
But, the elements of the array must be complete. */
diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp54.C b/gcc/testsuite/g++.dg/cpp1z/decomp54.C
new file mode 100644
index 00000000000..1bee772d5ba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp54.C
@@ -0,0 +1,17 @@
+// PR c++/97878
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+extern int a[];
+auto [b] { a }; // { dg-error "has incomplete type" }
+ // { dg-warning "only available with" "" { target c++14_down } .-1 }
+auto [c] = a; // { dg-error "has incomplete type" }
+ // { dg-warning "only available with" "" { target c++14_down } .-1 }
+extern int d[0];
+auto [e] { d }; // { dg-error "too many initializers for" }
+ // { dg-error "1 name provided for structured binding" "" { target *-*-* } .-1 }
+ // { dg-message "decomposes into 0 elements" "" { target *-*-* } .-2 }
+ // { dg-warning "only available with" "" { target c++14_down } .-3 }
+auto [f] = d; // { dg-error "1 name provided for structured binding" }
+ // { dg-message "decomposes into 0 elements" "" { target *-*-* } .-1 }
+ // { dg-warning "only available with" "" { target c++14_down } .-2 }
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