From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-x629.google.com (mail-pl1-x629.google.com [IPv6:2607:f8b0:4864:20::629]) by sourceware.org (Postfix) with ESMTPS id 9AF333858433 for ; Wed, 5 Apr 2023 17:36:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 9AF333858433 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pl1-x629.google.com with SMTP id iw3so35102091plb.6 for ; Wed, 05 Apr 2023 10:36:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680716172; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=wDz+8xdgxzmMIk/brx4UrcS4E34Zzm70ZbdbSnXw7/g=; b=SAyIeCr/kP/EQGp8k17pGXuxDksndpIyFN3/Pew94Q9W3PsR3oRTU6F5yyGXRJktEM 67uuJFlvKjme25/lHCJy9pbgYgcXI3kQF+8Y6xA90l8rFZbidrIWv/S6aOFqYCuINPfp SGVKm5BZy/FPUiYHmEUytjRPTmDPcLCmTSpXRnuGKCFQDPd4myDRmTSacNe2595cR8u+ Cv0hdLui3KAPs0PXZHkeJur45DLeD0SMTwjmu2m0KVSlnLLaqPotKiKlpnwBs66RQT7z juKYxWHQwcvB9M4qb4ALUtxlBy25AZlagY57fCDQdC5i74S+M9YxBfek+3NAGqF2P+qF lDtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680716172; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=wDz+8xdgxzmMIk/brx4UrcS4E34Zzm70ZbdbSnXw7/g=; b=YipQeqhYkq6BeNlrPHhbBOytQ06ynzD4EpstwUfPQcCSn1TF7IWdxkFCT5olHXATMN MPG7cTaHOkikMaBm6wla3Ocw5jPcFTQRz7M1QzeeIssZExUpVzkvZ57O6a84IznBvBvC Ir3CS89+TK8yQOdcOZhLfHEcdLoy9K7AOtBeu95es2VQhhS/XVWIoQs3aflN1HJhK3ki rRU7/9qL8qPO9CweARtIywAAyXZew9Ou9OMX4eaiwlXLqIeY8RmVbzA0Mu/3Rwoq9JLa zV0WLFSFAQ2sY4fwNqy/vqb5KrrpSE1pBawTikP4jJZYlbIBjPlh1IGX/F0UNgF5JVFz 7RmQ== X-Gm-Message-State: AAQBX9dIwWaa8uuyjZ1X6ojp09/FhNBORgKGy1vYoBmsFWPebNnkwlBU fTxX6iYtQ0pFSi4mSZ6AlWwgY6k0rDvEULyrlEY= X-Google-Smtp-Source: AKy350Yy/ReF4p5+/aANlaYl/KjV27lzbJJLxbDIFdR5w7pGLfSxmHOL9/euzXSUdokZX4qQNrS14Hj07qM15Z+7tHg= X-Received: by 2002:a17:902:dac7:b0:1a2:87a2:c927 with SMTP id q7-20020a170902dac700b001a287a2c927mr3004108plx.12.1680716172396; Wed, 05 Apr 2023 10:36:12 -0700 (PDT) MIME-Version: 1.0 References: <20230405165927.1987914-1-ppalka@redhat.com> In-Reply-To: From: Andrew Pinski Date: Wed, 5 Apr 2023 10:35:59 -0700 Message-ID: Subject: Re: [PATCH] c++: 'typename T::X' vs 'struct T::X' lookup [PR109420] To: Patrick Palka Cc: gcc-patches@gcc.gnu.org, jason@redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Apr 5, 2023 at 10:32=E2=80=AFAM Patrick Palka via Gcc-patches wrote: > > On Wed, 5 Apr 2023, Patrick Palka wrote: > > > r13-6098-g46711ff8e60d64 made make_typename_type no longer ignore > > non-types during the lookup, unless the TYPENAME_TYPE in question was > > followed by the :: scope resolution operator. But there is another > > exception to this rule: we need to ignore non-types during the lookup > > also if the TYPENAME_TYPE was named with a tag other than 'typename', > > such as 'struct' or 'enum', as per [dcl.type.elab]/5. > > > > This patch implements this additional exception. It occurred to me tha= t > > the tf_qualifying_scope flag is probably unnecessary if we'd use the > > scope_type tag more thoroughly, but that requires parser changes that > > are probably too risky at this stage. (I'm working on addressing the > > FIXME/TODOs here for GCC 14.) > > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK fo= r > > trunk? > > > > PR c++/109420 > > > > gcc/cp/ChangeLog: > > > > * decl.cc (make_typename_type): Also ignore non-types during > > the lookup if tag_type is something other than none_type or > > typename_type. > > * pt.cc (tsubst) : Pass class_type or > > enum_type as tag_type to make_typename_type as appropriate > > instead of always passing typename_type. > > > > gcc/testsuite/ChangeLog: > > > > * g++.dg/template/typename27.C: New test. > > --- > > gcc/cp/decl.cc | 9 ++++++++- > > gcc/cp/pt.cc | 9 ++++++++- > > gcc/testsuite/g++.dg/template/typename27.C | 19 +++++++++++++++++++ > > 3 files changed, 35 insertions(+), 2 deletions(-) > > create mode 100644 gcc/testsuite/g++.dg/template/typename27.C > > > > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc > > index 5369714f9b3..a0a20c5accc 100644 > > --- a/gcc/cp/decl.cc > > +++ b/gcc/cp/decl.cc > > @@ -4307,7 +4307,14 @@ make_typename_type (tree context, tree name, enu= m tag_types tag_type, > > lookup will stop when we hit a dependent base. */ > > if (!dependent_scope_p (context)) > > { > > - bool want_type =3D (complain & tf_qualifying_scope); > > + /* As per [dcl.type.elab]/5 and [temp.res.general]/3, ignore non= -types if > > + the tag corresponds to a class-key or 'enum' (or is scope_type),= or if > > + this typename is followed by :: as per [basic.lookup.qual.genera= l]/1. > > + TODO: If we'd set the scope_type tag accurately on all TYPENAME_= TYPEs > > + that are followed by :: then we wouldn't need the tf_qualifying_= scope > > + flag. */ > > + bool want_type =3D (tag_type !=3D none_type && tag_type !=3D typ= ename_type) > > + || (complain & tf_qualifying_scope); > > Here's v2 which just slightly improves this comment. I reckon [basic.loo= kup.elab] > is a better reference than [dcl.type.elab]/5 for justifying why the > lookup should be type-only for class-key and 'enum' TYPENAME_TYPEs. > > -- >8 -- > > PR c++/109420 > > gcc/cp/ChangeLog: > > * decl.cc (make_typename_type): Also ignore non-types during the > lookup if tag_type corresponds to an elaborated-type-specifier. > * pt.cc (tsubst) : Pass class_type or > enum_type as tag_type to make_typename_type as appropriate > instead of always passing typename_type. > > gcc/testsuite/ChangeLog: > > * g++.dg/template/typename27.C: New test. > --- > gcc/cp/decl.cc | 12 +++++++++++- > gcc/cp/pt.cc | 9 ++++++++- > gcc/testsuite/g++.dg/template/typename27.C | 19 +++++++++++++++++++ > 3 files changed, 38 insertions(+), 2 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/template/typename27.C > > diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc > index 5369714f9b3..772c059dc2c 100644 > --- a/gcc/cp/decl.cc > +++ b/gcc/cp/decl.cc > @@ -4307,7 +4307,17 @@ make_typename_type (tree context, tree name, enum = tag_types tag_type, > lookup will stop when we hit a dependent base. */ > if (!dependent_scope_p (context)) > { > - bool want_type =3D (complain & tf_qualifying_scope); > + /* We generally don't ignore non-types during TYPENAME_TYPE lookup > + (as per [temp.res.general]/3), unless > + - the tag corresponds to a class-key or 'enum' so > + [basic.lookup.elab] applies, or > + - the tag corresponds to scope_type or tf_qualifying_scope is > + set so [basic.lookup.qual]/1 applies. > + TODO: If we'd set/track the scope_type tag thoroughly on all > + TYPENAME_TYPEs that are followed by :: then we wouldn't need the > + tf_qualifying_scope flag. */ > + bool want_type =3D (tag_type !=3D none_type && tag_type !=3D typen= ame_type) > + || (complain & tf_qualifying_scope); > t =3D lookup_member (context, name, /*protect=3D*/2, want_type, co= mplain); > } > else > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 821e0035c08..09559c88f29 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -16580,9 +16580,16 @@ tsubst (tree t, tree args, tsubst_flags_t compla= in, tree in_decl) > return error_mark_node; > } > > + /* FIXME: TYPENAME_IS_CLASS_P conflates 'union' vs 'struct' vs 'c= lass' > + tags. TYPENAME_TYPE should probably remember the exact tag th= at > + was written. */ Yes I had a patch for that but I submitted during stage 4 of GCC 12 and never updated again during stage 1 of GCC 13. I hope to submit it again with updated changes post this patch. Thanks, Andrew > + enum tag_types tag > + =3D TYPENAME_IS_CLASS_P (t) ? class_type > + : TYPENAME_IS_ENUM_P (t) ? enum_type > + : typename_type; > tsubst_flags_t tcomplain =3D complain | tf_keep_type_decl; > tcomplain |=3D tst_ok_flag | qualifying_scope_flag; > - f =3D make_typename_type (ctx, f, typename_type, tcomplain); > + f =3D make_typename_type (ctx, f, tag, tcomplain); > if (f =3D=3D error_mark_node) > return f; > if (TREE_CODE (f) =3D=3D TYPE_DECL) > diff --git a/gcc/testsuite/g++.dg/template/typename27.C b/gcc/testsuite/g= ++.dg/template/typename27.C > new file mode 100644 > index 00000000000..61b3efd998e > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/typename27.C > @@ -0,0 +1,19 @@ > +// PR c++/109420 > + > +struct A { > + struct X { }; > + int X; > +}; > + > +struct B { > + enum E { }; > + enum F { E }; > +}; > + > +template > +void f() { > + struct T::X x; // OK, lookup ignores the data member 'int A::X' > + enum U::E e; // OK, lookup ignores the enumerator 'B::F::E' > +} > + > +template void f(); > -- > 2.40.0.153.g6369acd968 >