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author | Patrick Palka <ppalka@redhat.com> | 2022-12-01 20:11:53 -0500 |
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committer | Patrick Palka <ppalka@redhat.com> | 2022-12-01 20:11:53 -0500 |
commit | a4e577b044d69977f93b2cb7769dc991eadf2cf0 (patch) | |
tree | a404151051099e11b2d889a2e6f359558bdf9904 /gcc/cp/pt.cc | |
parent | 40adb39566c6e06809fc63ccade8d25bdfc8dd24 (diff) | |
download | gcc-a4e577b044d69977f93b2cb7769dc991eadf2cf0.zip gcc-a4e577b044d69977f93b2cb7769dc991eadf2cf0.tar.gz gcc-a4e577b044d69977f93b2cb7769dc991eadf2cf0.tar.bz2 |
c++: comptypes ICE with BOUND_TEMPLATE_TEMPLATE_PARMs [PR107539]
Here we end up giving the two BOUND_TEMPLATE_TEMPLATE_PARMs
C<decltype(f::t)> and C<decltype(g::t)> the same TYPE_CANONICAL because
the hash table that interns TYPE_CANONICAL for template type parameters
doesn't set the comparing_specializations flag which controls how
PARM_DECLs from different contexts compare equal.
Later, from spec_hasher::equal for the corresponding two specializations
A<C<decltype(f::t)>> and A<C<decltype(g::t)>>, we compare the two bound
ttps with comparing_specializations set hence they now (structurally)
compare different despite having the same TYPE_CANONICAL, and so we get
the error:
internal compiler error: same canonical type node for different types
'C<decltype (t)>' and 'C<decltype (t)>'
This suggests that we should be setting comparing_specializations from
ctp_hasher::equal to match spec_hasher::equal. But doing so introduces
a separate ICE in cpp2a/concepts-placeholder3.C:
internal compiler error: canonical types differ for identical types
'auto [requires ::same_as<<placeholder>, decltype(f::x)>]' and
'auto [requires ::same_as<<placeholder>, decltype(g::x)>]'
because norm_hasher::equal doesn't set comparing_specializations either.
I'm not sure when exactly we need to set comparing_specializations given
what it controls (TYPENAME_TYPE equality/hashing and PARM_DECL equality)
but it seems to be the conservative choice to set the flag wherever we
have a global hash table that relies on type equality. To that end this
patch sets comparing_specializations in ctp_hasher and norm_hasher, as
well as in atom_hasher and sat_hasher for good measure. This turns out
to be a compile time win of about 2% in some concepts tests, probably
because of the improved TYPENAME_TYPE hashing enabled by the flag.
PR c++/107539
gcc/cp/ChangeLog:
* constraint.cc (norm_hasher::hash, norm_hasher::equal): Set
comparing_specializations.
(sat_hasher::hash, sat_hasher::equal): Likewise.
* cp-tree.h (atom_hasher::hash, atom_hasher::equal): Likewise.
* pt.cc (ctp_hasher::hash, ctp_hasher::equal): Likewise.
gcc/testsuite/ChangeLog:
* g++.dg/template/canon-type-19.C: New test.
Diffstat (limited to 'gcc/cp/pt.cc')
-rw-r--r-- | gcc/cp/pt.cc | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 08de273..3169161 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -4492,18 +4492,23 @@ struct ctp_hasher : ggc_ptr_hash<tree_node> { static hashval_t hash (tree t) { + ++comparing_specializations; tree_code code = TREE_CODE (t); hashval_t val = iterative_hash_object (code, 0); val = iterative_hash_object (TEMPLATE_TYPE_LEVEL (t), val); val = iterative_hash_object (TEMPLATE_TYPE_IDX (t), val); if (TREE_CODE (t) == BOUND_TEMPLATE_TEMPLATE_PARM) val = iterative_hash_template_arg (TYPE_TI_ARGS (t), val); + --comparing_specializations; return val; } static bool equal (tree t, tree u) { - return comptypes (t, u, COMPARE_STRUCTURAL); + ++comparing_specializations; + bool eq = comptypes (t, u, COMPARE_STRUCTURAL); + --comparing_specializations; + return eq; } }; |