PR c++/19628

* cp-tree.h (builtin_valid_in_constant_expr_p): Declare.
* parser.c (cp_parser_postfix_expression): Accept function call in constant expression if builtin_valid_in_constant_expr_p is true for that function.
* pt.c (value_dependent_expression_p): Handle CALL_EXPRs properly.
* semantics.c (finish_id_expression): Accept function call in constant expression if builtin_valid_in_constant_expr_p is true for that function.
* tree.c (builtin_valid_in_constant_expr_p): New.

* g++/ext/builtin7.C: New.
* g++/ext/builtin8.C: New.

From-SVN: r94635