After r13-332-g88459c3965e2a2, it looks like we can safely remove the
NULL test from TMPL_ARGS_HAVE_MULTIPLE_LEVELS, which simplifies its
semantics.

And TMPL_ARGS_LEVEL should verify the level argument is sane in the
one-dimensional vector case.  This change uncovered a couple of latent
bugs: in try_class_unification, we weren't correctly copying
multidimensional targs, and in unify_pack_expansion it seems an
inequality test needs to be reversed (not sure about this latter fix,
the test was added in r8-6178-g2625472ffa519e FWIW).

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?  Also tested on cmcstl2 and range-v3.

gcc/cp/ChangeLog:

        * cp-tree.h (TMPL_ARGS_HAVE_MULTIPLE_LEVELS): Remove NULL test.
        (TMPL_ARGS_LEVEL): Assert LEVEL is 1 when
        TMPL_ARGS_HAVE_MULTIPLE_LEVELS is false.
        * pt.cc (try_class_unification): Correctly copy multidimensional
        targs.
        (unify_pack_expansion): Fix level comparison.
---
 gcc/cp/cp-tree.h |  5 +++--
 gcc/cp/pt.cc     | 12 ++++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index b6961a796af..f681d32ac93 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3766,7 +3766,7 @@ struct GTY(()) lang_decl {
 /* Nonzero if the template arguments is actually a vector of vectors,
    rather than just a vector.  */
 #define TMPL_ARGS_HAVE_MULTIPLE_LEVELS(NODE)                \
-  (NODE && TREE_VEC_LENGTH (NODE) && TREE_VEC_ELT (NODE, 0)  \
+  (TREE_VEC_LENGTH (NODE) && TREE_VEC_ELT (NODE, 0)  \
    && TREE_CODE (TREE_VEC_ELT (NODE, 0)) == TREE_VEC)
 
 /* The depth of a template argument vector.  When called directly by
@@ -3783,7 +3783,8 @@ struct GTY(()) lang_decl {
    args is level 1, not level 0.  */
 #define TMPL_ARGS_LEVEL(ARGS, LEVEL)           \
   (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (ARGS)       \
-   ? TREE_VEC_ELT (ARGS, (LEVEL) - 1) : (ARGS))
+   ? TREE_VEC_ELT (ARGS, (LEVEL) - 1)          \
+   : (gcc_checking_assert (LEVEL == 1), (ARGS)))
 
 /* Set the LEVELth level of the template ARGS to VAL.  This macro does
    not work with single-level argument vectors.  */
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 2c7c5f8bb5d..75b21e5c88a 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -23398,8 +23398,6 @@ static tree
 try_class_unification (tree tparms, tree targs, tree parm, tree arg,
                       bool explain_p)
 {
-  tree copy_of_targs;
-
   if (!CLASSTYPE_SPECIALIZATION_OF_PRIMARY_TEMPLATE_P (arg))
     return NULL_TREE;
   else if (TREE_CODE (parm) == BOUND_TEMPLATE_TEMPLATE_PARM)
@@ -23438,17 +23436,19 @@ try_class_unification (tree tparms, tree targs, tree 
parm, tree arg,
      because there are two ways to unify base classes of S<0, 1, 2>
      with S<I, I, I>.  If we kept the already deduced knowledge, we
      would reject the possibility I=1.  */
-  copy_of_targs = make_tree_vec (TREE_VEC_LENGTH (targs));
+  targs = copy_template_args (targs);
+  for (tree& targ : tree_vec_range (INNERMOST_TEMPLATE_ARGS (targs)))
+    targ = NULL_TREE;
 
   if (TREE_CODE (parm) == BOUND_TEMPLATE_TEMPLATE_PARM)
     {
-      if (unify_bound_ttp_args (tparms, copy_of_targs, parm, arg, explain_p))
+      if (unify_bound_ttp_args (tparms, targs, parm, arg, explain_p))
        return NULL_TREE;
       return arg;
     }
 
   /* If unification failed, we're done.  */
-  if (unify (tparms, copy_of_targs, CLASSTYPE_TI_ARGS (parm),
+  if (unify (tparms, targs, CLASSTYPE_TI_ARGS (parm),
             CLASSTYPE_TI_ARGS (arg), UNIFY_ALLOW_NONE, explain_p))
     return NULL_TREE;
 
@@ -23649,7 +23649,7 @@ unify_pack_expansion (tree tparms, tree targs, tree 
packed_parms,
 
       /* Determine the index and level of this parameter pack.  */
       template_parm_level_and_index (parm_pack, &level, &idx);
-      if (level < levels)
+      if (level > levels)
        continue;
 
       /* Keep track of the parameter packs and their corresponding
-- 
2.36.1.63.gef9b086d95

Reply via email to