Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for 15? (Or even trunk?)
-- >8 -- <https://wg21.link/p1381r1> clarifies that it's OK to capture structured bindings. [expr.prim.lambda.capture]/4 says "The identifier in a simple-capture shall denote a local entity" and [basic.pre]/3: "An entity is a [...] structured binding". It doesn't appear that this was made a DR, so, strictly speaking, we should have a -Wc++20-extensions warning, like clang++. PR c++/85889 gcc/cp/ChangeLog: * lambda.cc (add_capture): Add a pedwarn for capturing structured bindings. gcc/testsuite/ChangeLog: * g++.dg/cpp2a/decomp3.C: Use -Wno-c++20-extensions. * g++.dg/cpp1z/decomp60.C: New test. --- gcc/cp/lambda.cc | 9 +++++++++ gcc/testsuite/g++.dg/cpp1z/decomp60.C | 12 ++++++++++++ gcc/testsuite/g++.dg/cpp2a/decomp3.C | 2 +- 3 files changed, 22 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp1z/decomp60.C diff --git a/gcc/cp/lambda.cc b/gcc/cp/lambda.cc index 4b1f9391fee..470f9d2c4f1 100644 --- a/gcc/cp/lambda.cc +++ b/gcc/cp/lambda.cc @@ -607,6 +607,15 @@ add_capture (tree lambda, tree id, tree orig_init, bool by_reference_p, TCTX_CAPTURE_BY_COPY, type)) return error_mark_node; } + + if (cxx_dialect < cxx20) + { + tree stripped_init = tree_strip_any_location_wrapper (initializer); + if (DECL_DECOMPOSITION_P (stripped_init) + && pedwarn (input_location, OPT_Wc__20_extensions, + "captured structured bindings are a C++20 extension")) + inform (DECL_SOURCE_LOCATION (stripped_init), "declared here"); + } } /* Add __ to the beginning of the field name so that user code diff --git a/gcc/testsuite/g++.dg/cpp1z/decomp60.C b/gcc/testsuite/g++.dg/cpp1z/decomp60.C new file mode 100644 index 00000000000..b6117f3af58 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp1z/decomp60.C @@ -0,0 +1,12 @@ +// PR c++/85889 +// { dg-do compile { target c++17 } } +// { dg-options "" } + +struct X { int i, j; }; +void f() { + X x{}; + auto [i, j] = x; + [&i]() { }; // { dg-warning "captured structured bindings" "" { target c++17_only } } + [i]() { }; // { dg-warning "captured structured bindings" "" { target c++17_only } } +} + diff --git a/gcc/testsuite/g++.dg/cpp2a/decomp3.C b/gcc/testsuite/g++.dg/cpp2a/decomp3.C index 5e77973d41f..25ab8319975 100644 --- a/gcc/testsuite/g++.dg/cpp2a/decomp3.C +++ b/gcc/testsuite/g++.dg/cpp2a/decomp3.C @@ -1,6 +1,6 @@ // P1381R1 // { dg-do compile { target c++11 } } -// { dg-options "" } +// { dg-options "-Wno-c++20-extensions" } struct Foo { int a : 1; int b; }; base-commit: 574fd1f17f100c7c355ad26bc525ab5a3386bb2d -- 2.44.0
