c++: cv-qualified ref introduced by typedef [PR101783]

c++: cv-qualified ref introduced by typedef [PR101783]

The root cause of this bug is that it considers reference with
cv-qualifiers as an error by generating value for variable "bad_quals".
However, this is not correct for case of typedef. Here I quote spec
[dcl.ref]/1 :
"Cv-qualified references are ill-formed except when the cv-qualifiers
are introduced through the use of a typedef-name ([dcl.typedef],
[temp.param]) or decltype-specifier ([dcl.type.decltype]),
in which case the cv-qualifiers are ignored."

2021-09-30  qingzhe huang  <nickhuang99@hotmail.com>

gcc/cp/ChangeLog:
	PR c++/101783
	* tree.c (cp_build_qualified_type_real): Exclude typedef from
	error.

gcc/testsuite/ChangeLog:
	PR c++/101783
	* g++.dg/parse/pr101783.C: New test.