On 2/21/20 2:14 PM, Marek Polacek wrote:
This was approved in the Prague 2020 WG21 meeting so let's adjust the comment. Since it's supposed to be a DR I think we should no longer limit it to C++20.
I'm a bit nervous about the impact, but OK. It's easy enough to turn off -Wnarrowing if it's a problem for users.
Bootstrapped/regtested on x86_64-linux, ok for trunk? 2020-02-21 Marek Polacek <pola...@redhat.com> P1957R2 * typeck2.c (check_narrowing): Consider T* to bool narrowing in C++11 and up. * g++.dg/cpp0x/initlist92.C: Don't expect an error in C++20 only. --- gcc/cp/typeck2.c | 7 ++++--- gcc/testsuite/g++.dg/cpp0x/initlist92.C | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c index 48920894b3b..68bc2e5c170 100644 --- a/gcc/cp/typeck2.c +++ b/gcc/cp/typeck2.c @@ -1036,9 +1036,10 @@ check_narrowing (tree type, tree init, tsubst_flags_t complain, } else if (TREE_CODE (type) == BOOLEAN_TYPE && (TYPE_PTR_P (ftype) || TYPE_PTRMEM_P (ftype))) - /* This hasn't actually made it into C++20 yet, but let's add it now to get - an idea of the impact. */ - ok = (cxx_dialect < cxx2a); + /* C++20 P1957R2: converting from a pointer type or a pointer-to-member + type to bool should be considered narrowing. This is a DR so is not + limited to C++20 only. */ + ok = false;bool almost_ok = ok;if (!ok && !CONSTANT_CLASS_P (init) && (complain & tf_warning_or_error)) diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist92.C b/gcc/testsuite/g++.dg/cpp0x/initlist92.C index 319264ae274..213b192d441 100644 --- a/gcc/testsuite/g++.dg/cpp0x/initlist92.C +++ b/gcc/testsuite/g++.dg/cpp0x/initlist92.C @@ -23,7 +23,7 @@ bool Test4(std::initializer_list<std::string>);int main (){ - ( Test1({"false"}) ); // { dg-error "narrowing" "" { target c++2a } } + ( Test1({"false"}) ); // { dg-error "narrowing" } ( Test2({123}) ); ( Test3({456}) ); ( Test4({"false"}) ); base-commit: dbfba41e95d1d93b17e907b7f516b52ed3a3c415
