From 8aa045c97485d75e0b6eb1068464c0ddaa6beacb Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Tue, 20 Dec 2022 17:02:37 -0500 Subject: [PATCH] c++, tree: walk TREE_VEC (and VECTOR_CST) in natural order [PR101886] 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 instead of 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 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 not consistent with how we walk all other compound trees such as CONSTRUCTORs and EXPR_P trees in forward order. So this patch makes walk_tree_1 walk TREE_VEC (and VECTOR_CST) in forward order as well, which fixes the testcase. Doing so revealed that keep_template_parm grows the list of found template parameters from the front, which previously compensated for the TREE_VEC behavior, so now we should grow it from the back. 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 forward instead of reverse order. : Likewise. gcc/testsuite/ChangeLog: * g++.dg/concepts/diagnostic12.C: Adjust expected order of template parameters within pretty printed 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 83da1ba1bf5a..2d902988a439 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 000000000000..1f6d72e54ccf --- /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 548ba9c1b3d0..8086500760bf 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 0a51f9ddb4d8..92199bb65033 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: -- 2.47.2