From 4b2726a62ddfe958302d6790725503ac09b28f11 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 4 Feb 2025 09:23:15 +0100
Subject: [PATCH] c++: Fix up pedwarn for capturing structured bindings in
lambdas [PR118719]
As mentioned in the PR, this pedwarni is desirable for the implicit or
explicit capturing of structured bindings in C++17, but in the case of
init-captures the initializer is just some expression and that can include
structured bindings.
So, the following patch limits the warning to non-explicit_init_p.
2025-02-04 Jakub Jelinek <jakub@redhat.com>
PR c++/118719
* lambda.cc (add_capture): Only pedwarn about capturing structured
binding if !explicit_init_p.
* g++.dg/cpp1z/decomp63.C: New test.
---
gcc/cp/lambda.cc | 2 +-
gcc/testsuite/g++.dg/cpp1z/decomp63.C | 18 ++++++++++++++++++
2 files changed, 19 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/decomp63.C
diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc
index 5593636eaf8e..2d86e9892f99 100644
--- a/gcc/cp/lambda.cc
+++ b/gcc/cp/lambda.cc
@@ -613,7 +613,7 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p,
return error_mark_node;
}
- if (cxx_dialect < cxx20)
+ if (cxx_dialect < cxx20 && !explicit_init_p)
{
auto_diagnostic_group d;
tree stripped_init = tree_strip_any_location_wrapper (initializer);
diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp63.C b/gcc/testsuite/g++.dg/cpp1z/decomp63.C
new file mode 100644
index 000000000000..50049255efb1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/decomp63.C
@@ -0,0 +1,18 @@
+// PR c++/118719
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+int
+main ()
+{
+ int a[] = { 42 };
+ auto [x] = a; // { dg-warning "structured bindings only available with" "" { target c++14_down } }
+ // { dg-message "declared here" "" { target c++17_down } .-1 }
+ [=] () { int b = x; (void) b; }; // { dg-warning "captured structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
+ [&] () { int b = x; (void) b; }; // { dg-warning "captured structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
+ [x] () { int b = x; (void) b; }; // { dg-warning "captured structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
+ [&x] () { int b = x; (void) b; }; // { dg-warning "captured structured bindings are a C\\\+\\\+20 extension" "" { target c++17_down } }
+ [x = x] () { int b = x; (void) b; }; // { dg-warning "lambda capture initializers only available with" "" { target c++11_only } }
+ [y = x] () { int b = y; (void) b; }; // { dg-warning "lambda capture initializers only available with" "" { target c++11_only } }
+ [y = x * 2] () { int b = y; (void) b; }; // { dg-warning "lambda capture initializers only available with" "" { target c++11_only } }
+}
--
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