From f83adb68ed9cef1fbd4c16447eb4e89676df9f62 Mon Sep 17 00:00:00 2001 From: Patrick Palka Date: Sat, 18 Apr 2020 06:22:21 -0400 Subject: [PATCH] c++: spec_hasher::equal and PARM_DECLs [PR94632] In the testcase below, during specialization of c::d, we build two identical specializations of the parameter type b -- one when substituting into c::d's TYPE_ARG_TYPES and another when substituting into c::d's DECL_ARGUMENTS. We don't reuse the first specialization the second time around as a consequence of the fix for PR c++/56247 which made PARM_DECLs always compare different from one another during spec_hasher::equal. As a result, when looking up existing specializations of 'b', spec_hasher::equal considers the template argument decltype(e')::k to be different from decltype(e'')::k, where e' and e'' are the result of two calls to tsubst_copy on the PARM_DECL e. Since the two specializations are considered different due to the mentioned fix, their TYPE_CANONICAL points to themselves even though they are otherwise identical types, and this triggers an ICE in maybe_rebuild_function_decl_type when comparing the TYPE_ARG_TYPES of c::d to its DECL_ARGUMENTS. This patch fixes this issue at the spec_hasher::equal level by ignoring the 'comparing_specializations' flag in cp_tree_equal whenever the DECL_CONTEXTs of the two parameters are identical. This seems to be a sufficient condition to be able to correctly compare PARM_DECLs structurally. (This also subsumes the CONSTRAINT_VAR_P check since constraint variables all have empty, and therefore identical, DECL_CONTEXTs.) gcc/cp/ChangeLog: PR c++/94632 * tree.c (cp_tree_equal) : Ignore comparing_specializations if the parameters' contexts are identical. gcc/testsuite/ChangeLog: PR c++/94632 * g++.dg/template/canon-type-14.C: New test. --- gcc/cp/ChangeLog | 4 ++++ gcc/cp/tree.c | 5 +++-- gcc/testsuite/ChangeLog | 3 +++ gcc/testsuite/g++.dg/template/canon-type-14.C | 8 ++++++++ 4 files changed, 18 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/canon-type-14.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 45c422f5950..9533cca7137 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,9 @@ 2020-04-18 Patrick Palka + PR c++/94632 + * tree.c (cp_tree_equal) : Ignore + comparing_specializations if the parameters' contexts are identical. + PR c++/92187 * pt.c (splice_late_return_type): Propagate cv-qualifiers and PLACEHOLDER_TYPE_CONSTRAINTS from the original auto node to the new one. diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c index 8e4934c0009..dc4f1f48d3c 100644 --- a/gcc/cp/tree.c +++ b/gcc/cp/tree.c @@ -3723,11 +3723,12 @@ cp_tree_equal (tree t1, tree t2) up for expressions that involve 'this' in a member function template. */ - if (comparing_specializations && !CONSTRAINT_VAR_P (t1)) + if (comparing_specializations + && DECL_CONTEXT (t1) != DECL_CONTEXT (t2)) /* When comparing hash table entries, only an exact match is good enough; we don't want to replace 'this' with the version from another function. But be more flexible - with local parameters in a requires-expression. */ + with parameters with identical contexts. */ return false; if (same_type_p (TREE_TYPE (t1), TREE_TYPE (t2))) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 08bef53e911..a41cc03f6fa 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,8 @@ 2020-04-18 Patrick Palka + PR c++/94632 + * g++.dg/template/canon-type-14.C: New test. + PR c++/92187 * g++.dg/concepts/abbrev5.C: New test. * g++.dg/concepts/abbrev6.C: New test. diff --git a/gcc/testsuite/g++.dg/template/canon-type-14.C b/gcc/testsuite/g++.dg/template/canon-type-14.C new file mode 100644 index 00000000000..fa05bdb9a74 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/canon-type-14.C @@ -0,0 +1,8 @@ +// PR c++/94632 +// { dg-do compile { target c++11 } } + +template struct b; +template class c { + template static void d(f e, b); +}; +template class c; -- 2.30.2