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[130.44.159.43]) by smtp.gmail.com with ESMTPSA id bp31-20020a05620a459f00b006bb2cd2f6d1sm9680688qkb.127.2022.12.20.13.29.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Dec 2022 13:29:43 -0800 (PST) Message-ID: <9de3b217-182f-e33e-1fea-d84d923332b7@redhat.com> Date: Tue, 20 Dec 2022 16:29:42 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.1 Subject: Re: [PATCH] c++, tree: walk TREE_VEC (and VECTOR_CST) in natural order [PR101886] To: Patrick Palka , gcc-patches@gcc.gnu.org References: <20221220153034.2746407-1-ppalka@redhat.com> From: Jason Merrill In-Reply-To: <20221220153034.2746407-1-ppalka@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-13.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,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 12/20/22 10:30, Patrick Palka wrote: > Unfortunately the extract_autos_r fix in r13-4799-ga7c8036b26082d is > derailed by the fact that walk_tree_1 currently walks the elements of a > TREE_VEC in reverse, which means for A in the below testcase > extract_autos_r ends up adjusting the TEMPLATE_TYPE_IDX of the first > auto rather than the second one, and the first auto is the canonical > auto of level 2 and index 0, so we rightfully trigger the sanity check > added in that commit. > > It seems TREE_VEC and VECTOR_CST are the only trees that we walk in > reverse, and this has been the case since r21884 whence the original > version of walk_tree_1 was introduced. But that's arguably unnatural > and inconsistent with how we walk other compound trees such as > CONSTRUCTORs and EXPR_P trees. So this patch makes walk_tree_1 walk > these trees in forward order, which fixes the below testcase. This in > turn revealed that keep_template_parm builds up the list of found > template parameters in reverse, which previously compensated for the > TREE_VEC behavior, but now we should be building the list in the natural > order as well for sake of pretty printing parameter mappings. > > Bootstrapped and regtested on x86_64-pc-linux-gnu with > --enable-languages=all,ada,go does this look OK for trunk? OK. > PR c++/101886 > > gcc/cp/ChangeLog: > > * pt.cc (find_template_parameter_info::parm_list_tail): > New data member. > (keep_template_parm): Use parm_list_tail to append rather > than prepend to parm_list. > > gcc/ChangeLog: > > * tree.cc (walk_tree_1) : Walk the elements > in the natural order. > : Likewise. > > gcc/testsuite/ChangeLog: > > * g++.dg/concepts/diagnostic12.C: Adjust expected order of > template parameters within parameter mapping. > * g++.dg/concepts/auto6.C: New test. > --- > gcc/cp/pt.cc | 13 +++++++++---- > gcc/testsuite/g++.dg/concepts/auto6.C | 14 ++++++++++++++ > gcc/testsuite/g++.dg/concepts/diagnostic12.C | 2 +- > gcc/tree.cc | 20 ++++++++++---------- > 4 files changed, 34 insertions(+), 15 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/concepts/auto6.C > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc > index 2b7b3756b68..df125a63785 100644 > --- a/gcc/cp/pt.cc > +++ b/gcc/cp/pt.cc > @@ -10640,14 +10640,14 @@ for_each_template_parm (tree t, tree_fn_t fn, void* data, > struct find_template_parameter_info > { > explicit find_template_parameter_info (tree ctx_parms) > - : parm_list (NULL_TREE), > - ctx_parms (ctx_parms), > + : ctx_parms (ctx_parms), > max_depth (TMPL_PARMS_DEPTH (ctx_parms)) > {} > > hash_set visited; > hash_set parms; > - tree parm_list; > + tree parm_list = NULL_TREE; > + tree *parm_list_tail = &parm_list; > tree ctx_parms; > int max_depth; > }; > @@ -10693,7 +10693,12 @@ keep_template_parm (tree t, void* data) > if (TYPE_P (t)) > t = TYPE_MAIN_VARIANT (t); > if (!ftpi->parms.add (t)) > - ftpi->parm_list = tree_cons (NULL_TREE, t, ftpi->parm_list); > + { > + /* Append T to PARM_LIST. */ > + tree node = build_tree_list (NULL_TREE, t); > + *ftpi->parm_list_tail = node; > + ftpi->parm_list_tail = &TREE_CHAIN (node); > + } > > /* Verify the parameter we found has a valid index. */ > if (flag_checking) > diff --git a/gcc/testsuite/g++.dg/concepts/auto6.C b/gcc/testsuite/g++.dg/concepts/auto6.C > new file mode 100644 > index 00000000000..1f6d72e54cc > --- /dev/null > +++ b/gcc/testsuite/g++.dg/concepts/auto6.C > @@ -0,0 +1,14 @@ > +// PR c++/101886 > +// { dg-do compile { target c++17_only } } > +// { dg-options "-fconcepts-ts" } > + > +template struct A { }; > + > +template > +void f() { > + A a; > + A b1 = a; > + A b2 = a; > +} > + > +template void f(); > diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic12.C b/gcc/testsuite/g++.dg/concepts/diagnostic12.C > index 548ba9c1b3d..8086500760b 100644 > --- a/gcc/testsuite/g++.dg/concepts/diagnostic12.C > +++ b/gcc/testsuite/g++.dg/concepts/diagnostic12.C > @@ -3,7 +3,7 @@ > > template > concept c1 = requires (T t, Args... args) { *t; }; > -// { dg-message "in requirements with .T t., .Args ... args. .with Args = \{\}; T = int" "" { target *-*-* } .-1 } > +// { dg-message "in requirements with .T t., .Args ... args. .with T = int; Args = \{\}" "" { target *-*-* } .-1 } > > static_assert(c1); // { dg-error "failed" } > > diff --git a/gcc/tree.cc b/gcc/tree.cc > index 0a51f9ddb4d..92199bb6503 100644 > --- a/gcc/tree.cc > +++ b/gcc/tree.cc > @@ -11310,12 +11310,12 @@ walk_tree_1 (tree *tp, walk_tree_fn func, void *data, > if (len == 0) > break; > > - /* Walk all elements but the first. */ > - while (--len) > - WALK_SUBTREE (TREE_VEC_ELT (*tp, len)); > + /* Walk all elements but the last. */ > + for (int i = 0; i < len - 1; ++i) > + WALK_SUBTREE (TREE_VEC_ELT (*tp, i)); > > - /* Now walk the first one as a tail call. */ > - WALK_SUBTREE_TAIL (TREE_VEC_ELT (*tp, 0)); > + /* Now walk the last one as a tail call. */ > + WALK_SUBTREE_TAIL (TREE_VEC_ELT (*tp, len - 1)); > } > > case VECTOR_CST: > @@ -11323,11 +11323,11 @@ walk_tree_1 (tree *tp, walk_tree_fn func, void *data, > unsigned len = vector_cst_encoded_nelts (*tp); > if (len == 0) > break; > - /* Walk all elements but the first. */ > - while (--len) > - WALK_SUBTREE (VECTOR_CST_ENCODED_ELT (*tp, len)); > - /* Now walk the first one as a tail call. */ > - WALK_SUBTREE_TAIL (VECTOR_CST_ENCODED_ELT (*tp, 0)); > + /* Walk all elements but the last. */ > + for (unsigned i = 0; i < len - 1; ++i) > + WALK_SUBTREE (VECTOR_CST_ENCODED_ELT (*tp, i)); > + /* Now walk the last one as a tail call. */ > + WALK_SUBTREE_TAIL (VECTOR_CST_ENCODED_ELT (*tp, len - 1)); > } > > case COMPLEX_CST: