From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1734) id F218E3858D28; Tue, 7 Dec 2021 14:30:45 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F218E3858D28 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Marek Polacek To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-9363] c++: Fix for decltype and bit-fields [PR95009] X-Act-Checkin: gcc X-Git-Author: Marek Polacek X-Git-Refname: refs/heads/releases/gcc-11 X-Git-Oldrev: 15563293a9210c43e8156ce1dee098ee9cb6d6ea X-Git-Newrev: e3fab19a79e3dc3cdf3e54ca20107e1dc15a3927 Message-Id: <20211207143045.F218E3858D28@sourceware.org> Date: Tue, 7 Dec 2021 14:30:45 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Dec 2021 14:30:46 -0000 https://gcc.gnu.org/g:e3fab19a79e3dc3cdf3e54ca20107e1dc15a3927 commit r11-9363-ge3fab19a79e3dc3cdf3e54ca20107e1dc15a3927 Author: Marek Polacek Date: Sat Dec 4 12:07:41 2021 -0500 c++: Fix for decltype and bit-fields [PR95009] Here, decltype deduces the wrong type for certain expressions involving bit-fields. Unlike in C, in C++ bit-field width is explicitly not part of the type, so I think decltype should never deduce to 'int:N'. The problem isn't that we're not calling unlowered_expr_type--we are--it's that is_bitfield_expr_with_lowered_type only handles certain codes, but not others. For example, += works fine but ++ does not. This also fixes decltype-bitfield2.C where we were crashing (!), but unfortunately it does not fix 84516 or 70733 where the problem is likely a missing call to unlowered_expr_type. It occurs to me now that typeof likely has had the same issue, but this patch should fix that too. PR c++/95009 gcc/cp/ChangeLog: * typeck.c (is_bitfield_expr_with_lowered_type) : Handle UNARY_PLUS_EXPR, NEGATE_EXPR, NON_LVALUE_EXPR, BIT_NOT_EXPR, P*CREMENT_EXPR too. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/decltype-bitfield1.C: New test. * g++.dg/cpp0x/decltype-bitfield2.C: New test. (cherry picked from commit 3a2257e6b3fa288d6c50831987949b9ff7dfb865) Diff: --- gcc/cp/typeck.c | 14 ++++-- gcc/testsuite/g++.dg/cpp0x/decltype-bitfield1.C | 65 +++++++++++++++++++++++++ gcc/testsuite/g++.dg/cpp0x/decltype-bitfield2.C | 18 +++++++ 3 files changed, 94 insertions(+), 3 deletions(-) diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index 1b68c53b831..6241cd080ec 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -2039,9 +2039,9 @@ invalid_nonstatic_memfn_p (location_t loc, tree expr, tsubst_flags_t complain) return false; } -/* If EXP is a reference to a bitfield, and the type of EXP does not - match the declared type of the bitfield, return the declared type - of the bitfield. Otherwise, return NULL_TREE. */ +/* If EXP is a reference to a bit-field, and the type of EXP does not + match the declared type of the bit-field, return the declared type + of the bit-field. Otherwise, return NULL_TREE. */ tree is_bitfield_expr_with_lowered_type (const_tree exp) @@ -2060,6 +2060,14 @@ is_bitfield_expr_with_lowered_type (const_tree exp) case MODIFY_EXPR: case SAVE_EXPR: + case UNARY_PLUS_EXPR: + case PREDECREMENT_EXPR: + case PREINCREMENT_EXPR: + case POSTDECREMENT_EXPR: + case POSTINCREMENT_EXPR: + case NEGATE_EXPR: + case NON_LVALUE_EXPR: + case BIT_NOT_EXPR: return is_bitfield_expr_with_lowered_type (TREE_OPERAND (exp, 0)); case COMPONENT_REF: diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield1.C b/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield1.C new file mode 100644 index 00000000000..2d8d8e81bff --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield1.C @@ -0,0 +1,65 @@ +// PR c++/95009 +// { dg-do compile { target c++11 } } + +struct false_type { static constexpr bool value = false; }; +struct true_type { static constexpr bool value = true; }; +template +struct is_same : false_type {}; +template +struct is_same : true_type {}; + +struct A { + int i : 31; + unsigned long l : 37; +} a; + +void +g () +{ + // Careful: pre{in,de}crements are lvalues -> deduce T&. */ + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); + static_assert (is_same::value, ""); +} diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield2.C b/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield2.C new file mode 100644 index 00000000000..4bf9c7682ff --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/decltype-bitfield2.C @@ -0,0 +1,18 @@ +// PR c++/95009 +// { dg-do compile { target c++11 } } + +struct A { + int i:31; +}; + +template +void f () +{ +} + +int main () +{ + A a; + f(); + f(); +}