From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1888) id A1188384D17E; Thu, 21 Jul 2022 16:48:12 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A1188384D17E MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Patrick Palka To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-8604] c++: function NTTP argument considered unused [PR53164, PR105848] X-Act-Checkin: gcc X-Git-Author: Patrick Palka X-Git-Refname: refs/heads/releases/gcc-12 X-Git-Oldrev: 41487bff13fa98607ab5548bc1a0dca71147a5ac X-Git-Newrev: 670ef5b108d0acfbde96f44b064079f2fa0c92d4 Message-Id: <20220721164812.A1188384D17E@sourceware.org> Date: Thu, 21 Jul 2022 16:48:12 +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: Thu, 21 Jul 2022 16:48:12 -0000 https://gcc.gnu.org/g:670ef5b108d0acfbde96f44b064079f2fa0c92d4 commit r12-8604-g670ef5b108d0acfbde96f44b064079f2fa0c92d4 Author: Patrick Palka Date: Mon Jun 6 14:29:12 2022 -0400 c++: function NTTP argument considered unused [PR53164, PR105848] Here at parse time the template argument f (an OVERLOAD) in A gets resolved ahead of time to the FUNCTION_DECL f, and we defer marking f as used until instantiation (of g) as usual. Later when instantiating g the type A (where f has already been resolved) is non-dependent, so tsubst_aggr_type avoids re-processing its template arguments, and we end up never actually marking f as used (which means we never instantiate it) even though A::h() later calls it, leading to a link error. This patch works around this issue by looking through ADDR_EXPR when calling mark_used on the substituted callee of a CALL_EXPR. PR c++/53164 PR c++/105848 gcc/cp/ChangeLog: * pt.cc (tsubst_copy_and_build) : Look through an ADDR_EXPR callee when calling mark_used. gcc/testsuite/ChangeLog: * g++.dg/template/fn-ptr3.C: New test. (cherry picked from commit 733a792a2b2e1662e738fa358b45a2720a8618a7) Diff: --- gcc/cp/pt.cc | 20 ++++++++++++++++---- gcc/testsuite/g++.dg/template/fn-ptr3.C | 28 ++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 4 deletions(-) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index b2b1a5d1ec6..38c138bd835 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -20926,10 +20926,22 @@ tsubst_copy_and_build (tree t, } /* Remember that there was a reference to this entity. */ - if (function != NULL_TREE - && DECL_P (function) - && !mark_used (function, complain) && !(complain & tf_error)) - RETURN (error_mark_node); + if (function != NULL_TREE) + { + tree inner = function; + if (TREE_CODE (inner) == ADDR_EXPR + && TREE_CODE (TREE_OPERAND (inner, 0)) == FUNCTION_DECL) + /* We should already have called mark_used when taking the + address of this function, but do so again anyway to make + sure it's odr-used: at worst this is a no-op, but if we + obtained this FUNCTION_DECL as part of ahead-of-time overload + resolution then that call to mark_used wouldn't have marked it + odr-used yet (53164). */ + inner = TREE_OPERAND (inner, 0); + if (DECL_P (inner) + && !mark_used (inner, complain) && !(complain & tf_error)) + RETURN (error_mark_node); + } if (!maybe_fold_fn_template_args (function, complain)) return error_mark_node; diff --git a/gcc/testsuite/g++.dg/template/fn-ptr3.C b/gcc/testsuite/g++.dg/template/fn-ptr3.C new file mode 100644 index 00000000000..4c651f124f6 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/fn-ptr3.C @@ -0,0 +1,28 @@ +// PR c++/53164 +// PR c++/105848 +// { dg-do link } + +template +void f(T) { } + +template +struct A { + static void wrap() { + P(0); + } +}; + +template +void wrap() { + P(0); +} + +template +void g() { + A::wrap(); + wrap(); +} + +int main() { + g<0>(); +}