Hi!
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.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2025-02-02 Jakub Jelinek <ja...@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.jj 2025-01-24 17:37:49.004457905 +0100
+++ gcc/cp/lambda.cc 2025-01-31 23:47:08.907034696 +0100
@@ -613,7 +613,7 @@ add_capture (tree lambda, tree id, tree
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);
--- gcc/testsuite/g++.dg/cpp1z/decomp63.C.jj 2025-01-31 23:54:15.480699418
+0100
+++ gcc/testsuite/g++.dg/cpp1z/decomp63.C 2025-01-31 23:53:02.998578507
+0100
@@ -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 } }
+}
Jakub
