c++: remove i_c_e_p parm from tsubst_copy_and_build

It seems the only and original purpose of tsubst_copy_and_build's
integral_constant_expression_p boolean parameter (added in r116276, which
predates the constexpr machinery) is to diagnose certain constructs that
aren't allowed to appear in a C++98 integral constant expression
context, specifically casts to a non-integral type (diagnosed from the
*_CAST_EXPR case of tsubst_copy_and_build) or dependent names that
resolve to a non-constant decl (diagnosed from the IDENTIFIER_NODE case
of tsubst_copy_and_build).  The parameter has no effect outside of C++98
AFAICT.

But diagnosing such constructs should arguably be the job of the constexpr
machinery (e.g. is_constant_expression) after substitution, and doing it
during substitution by way of an additional parameter complicates the
API of this workhorse function for what amounts to a couple of archaic
C++98 restrictions.  And it seems is_constant_expression already does a
good job of diagnosing the aforementioned two constructs in C++98 mode,
at least as far as our testsuite is concerned.

So this patch removes this parameter from tsubst_copy_and_build,
tsubst_expr and tsubst_copy_and_build_call_args.  The only interesting
changes are to potential_constant_expression_1 and the IDENTIFIER_NODE
and *_CAST_EXPR cases of tsubst_copy_and_build; the rest are mechanical
adjustments to the functions' signatures and their call sites.

gcc/cp/ChangeLog:

	* constexpr.cc (potential_constant_expression_1)
	<case *_CAST_EXPR>: Use
	cast_valid_in_integral_constant_expression_p instead of
	open coding it.
	* constraint.cc (tsubst_valid_expression_requirement): Adjust
	calls to tsubst_copy_and_build and tsubst_expr.
	(tsubst_constraint): Likewise.
	(satisfy_atom): Likewise.
	(diagnose_trait_expr): Likewise.
	* cp-tree.h (tsubst_copy_and_build): Remove i_c_e_p parameter.
	(tsubst_expr): Likewise.
	* init.cc (get_nsdmi): Adjust calls to tsubst_copy_and_build
	and tsubst_expr.
	* pt.cc (expand_integer_pack): Likewise.
	(instantiate_non_dependent_expr_internal): Likewise.
	(tsubst_friend_function): Likewise.
	(tsubst_attribute): Likewise.
	(instantiate_class_template): Likewise.
	(tsubst_template_arg): Likewise.
	(gen_elem_of_pack_expansion_instantiation): Likewise.
	(tsubst_fold_expr_init): Likewise.
	(tsubst_pack_expansion): Likewise.
	(tsubst_default_argument): Likewise.
	(tsubst_function_decl): Likewise.
	(tsubst_decl): Likewise.
	(tsubst_arg_types): Likewise.
	(tsubst_exception_specification): Likewise.
	(tsubst): Likewise.
	(tsubst_init): Likewise.
	(tsubst_copy): Likewise.
	(tsubst_omp_clause_decl): Likewise.
	(tsubst_omp_clauses): Likewise.
	(tsubst_copy_asm_operands): Likewise.
	(tsubst_omp_for_iterator): Likewise.
	(tsubst_expr): Likewise.  Remove i_c_e_p parameter.
	(tsubst_omp_udr): Likewise.
	(tsubst_non_call_postfix_expression): Likewise.  Remove i_c_e_p parameter.
	(tsubst_lambda_expr): Likewise.
	(tsubst_copy_and_build_call_args): Likewise.
	(tsubst_copy_and_build): Likewise.  Remove i_c_e_p parameter.
	<case IDENTIFIER_NODE>: Adjust call to finish_id_expression
	following removal of i_c_e_p.
	<case *_CAST_EXPR>: Remove C++98-specific cast validity check
	guarded by i_c_e_p.
	(maybe_instantiate_noexcept): Adjust calls to
	tsubst_copy_and_build and tsubst_expr.
	(instantiate_body): Likewise.
	(instantiate_decl): Likewise.
	(tsubst_initializer_list): Likewise.
	(tsubst_enum): Likewise.

gcc/objcp/ChangeLog:

	* objcp-lang.cc (objcp_tsubst_copy_and_build): Adjust calls to
	tsubst_copy_and_build and tsubst_expr.

gcc/testsuite/ChangeLog:

	* g++.dg/template/crash55.C: Don't expect additional
	C++98-specific diagnostics.
	* g++.dg/template/ref3.C: Remove C++98-specific xfail.

1 files changed, 7 insertions, 7 deletions

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index f6ef078..3ddbd53 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -1921,7 +1921,7 @@ hash_placeholder_constraint (tree c)
 static tree
 tsubst_valid_expression_requirement (tree t, tree args, sat_info info)
 {
-  tree r = tsubst_expr (t, args, tf_none, info.in_decl, false);
+  tree r = tsubst_expr (t, args, tf_none, info.in_decl);
   if (convert_to_void (r, ICV_STATEMENT, tf_none) != error_mark_node)
     return r;
 
@@ -1932,7 +1932,7 @@ tsubst_valid_expression_requirement (tree t, tree args, sat_info info)
 	{
 	  inform (loc, "the required expression %qE is invalid, because", t);
 	  if (r == error_mark_node)
-	    tsubst_expr (t, args, info.complain, info.in_decl, false);
+	    tsubst_expr (t, args, info.complain, info.in_decl);
 	  else
 	    convert_to_void (r, ICV_STATEMENT, info.complain);
 	}
@@ -1941,7 +1941,7 @@ tsubst_valid_expression_requirement (tree t, tree args, sat_info info)
     }
   else if (info.noisy ())
     {
-      r = tsubst_expr (t, args, info.complain, info.in_decl, false);
+      r = tsubst_expr (t, args, info.complain, info.in_decl);
       convert_to_void (r, ICV_STATEMENT, info.complain);
     }
 
@@ -2706,7 +2706,7 @@ tsubst_constraint (tree t, tree args, tsubst_flags_t complain, tree in_decl)
      constraint-expressions of a declaration.  */
   processing_constraint_expression_sentinel s;
   cp_unevaluated u;
-  tree expr = tsubst_expr (t, args, complain, in_decl, false);
+  tree expr = tsubst_expr (t, args, complain, in_decl);
   return expr;
 }
 
@@ -2954,13 +2954,13 @@ satisfy_atom (tree t, tree args, sat_info info)
 
   /* Apply the parameter mapping (i.e., just substitute).  */
   tree expr = ATOMIC_CONSTR_EXPR (t);
-  tree result = tsubst_expr (expr, args, quiet.complain, quiet.in_decl, false);
+  tree result = tsubst_expr (expr, args, quiet.complain, quiet.in_decl);
   if (result == error_mark_node)
     {
       /* If substitution results in an invalid type or expression, the constraint
 	 is not satisfied. Replay the substitution.  */
       if (info.diagnose_unsatisfaction_p ())
-	tsubst_expr (expr, args, info.complain, info.in_decl, false);
+	tsubst_expr (expr, args, info.complain, info.in_decl);
       return cache.save (inst_cache.save (boolean_false_node));
     }
 
@@ -3587,7 +3587,7 @@ diagnose_trait_expr (tree expr, tree args)
   /* Build a "fake" version of the instantiated trait, so we can
      get the instantiated types from result.  */
   ++processing_template_decl;
-  expr = tsubst_expr (expr, args, tf_none, NULL_TREE, false);
+  expr = tsubst_expr (expr, args, tf_none, NULL_TREE);
   --processing_template_decl;
 
   tree t1 = TRAIT_EXPR_TYPE1 (expr);