[gcc r14-1518] c++: simplify TEMPLATE_TEMPLATE_PARM hashing

[gcc r14-1518] c++: simplify TEMPLATE_TEMPLATE_PARM hashing

[Patrick Palka]

https://gcc.gnu.org/g:23bee8508816297a9b2ab81a96aa0c79ac88ceba

commit r14-1518-g23bee8508816297a9b2ab81a96aa0c79ac88ceba
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat Jun 3 09:22:52 2023 -0400

    c++: simplify TEMPLATE_TEMPLATE_PARM hashing
    
    r10-7815-gaa576f2a860c82 added special hashing for TEMPLATE_TEMPLATE_PARM
    to work around non-lowered ttps having TYPE_CANONICAL set but lowered
    ttps did not.  But ever since r13-737-gd0ef9e06197d14 this is no longer
    the case, and all ttps should now have TYPE_CANONICAL set.  So this
    special hashing is now unnecessary and we can fall back to always using
    TYPE_CANONICAL.
    
    gcc/cp/ChangeLog:
    
            * pt.cc (iterative_hash_template_arg): Don't hash
            TEMPLATE_TEMPLATE_PARM specially.

Diff:
---
 gcc/cp/pt.cc | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 244b0b03454..dae3815f62a 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -1879,19 +1879,8 @@ iterative_hash_template_arg (tree arg, hashval_t val)
 	  return hash_tmpl_and_args (TI_TEMPLATE (ti), TI_ARGS (ti));
 	}
 
-      switch (TREE_CODE (arg))
+      switch (code)
 	{
-	case TEMPLATE_TEMPLATE_PARM:
-	  {
-	    tree tpi = TEMPLATE_TYPE_PARM_INDEX (arg);
-
-	    /* Do not recurse with TPI directly, as that is unbounded
-	       recursion.  */
-	    val = iterative_hash_object (TEMPLATE_PARM_LEVEL (tpi), val);
-	    val = iterative_hash_object (TEMPLATE_PARM_IDX (tpi), val);
-	  }
-	  break;
-
 	case  DECLTYPE_TYPE:
 	  val = iterative_hash_template_arg (DECLTYPE_TYPE_EXPR (arg), val);
 	  break;