import com.sun.tools.javac.code.Type.ForAll.ConstraintKind; //导入依赖的package包/类
/** Try to instantiate expression type `that' to given type `to'.
 *  If a maximal instantiation exists which makes this type
 *  a subtype of type `to', return the instantiated type.
 *  If no instantiation exists, or if several incomparable
 *  best instantiations exist throw a NoInstanceException.
 */
public Type instantiateExpr(ForAll that,
                            Type to,
                            Warner warn) throws InferenceException {
    List<Type> undetvars = Type.map(that.tvars, fromTypeVarFun);
    for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) {
        UndetVar uv = (UndetVar) l.head;
        TypeVar tv = (TypeVar)uv.qtype;
        ListBuffer<Type> hibounds = new ListBuffer<Type>();
        for (Type t : that.getConstraints(tv, ConstraintKind.EXTENDS)) {
            hibounds.append(types.subst(t, that.tvars, undetvars));
        }

        List<Type> inst = that.getConstraints(tv, ConstraintKind.EQUAL);
        if (inst.nonEmpty() && inst.head.tag != BOT) {
            uv.inst = inst.head;
        }
        uv.hibounds = hibounds.toList();
    }
    Type qtype1 = types.subst(that.qtype, that.tvars, undetvars);
    if (!types.isSubtype(qtype1,
            qtype1.tag == UNDETVAR ? types.boxedTypeOrType(to) : to)) {
        throw unambiguousNoInstanceException
            .setMessage("infer.no.conforming.instance.exists",
                        that.tvars, that.qtype, to);
    }
    for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail)
        maximizeInst((UndetVar) l.head, warn);
    // System.out.println(" = " + qtype1.map(getInstFun));//DEBUG

    // check bounds
    List<Type> targs = Type.map(undetvars, getInstFun);
    if (Type.containsAny(targs, that.tvars)) {
        //replace uninferred type-vars
        targs = types.subst(targs,
                that.tvars,
                instantiateAsUninferredVars(undetvars, that.tvars));
    }
    return chk.checkType(warn.pos(), that.inst(targs, types), to);
}
 

import com.sun.tools.javac.code.Type.ForAll.ConstraintKind; //导入依赖的package包/类
/** Try to instantiate expression type `that' to given type `to'.
 *  If a maximal instantiation exists which makes this type
 *  a subtype of type `to', return the instantiated type.
 *  If no instantiation exists, or if several incomparable
 *  best instantiations exist throw a NoInstanceException.
 */
public Type instantiateExpr(ForAll that,
                            Type to,
                            Warner warn) throws InferenceException {
    List<Type> undetvars = Type.map(that.tvars, fromTypeVarFun);
    for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail) {
        UndetVar uv = (UndetVar) l.head;
        TypeVar tv = (TypeVar)uv.qtype;
        ListBuffer<Type> hibounds = new ListBuffer<Type>();
        for (Type t : that.getConstraints(tv, ConstraintKind.EXTENDS)) {
            hibounds.append(types.subst(t, that.tvars, undetvars));
        }

        List<Type> inst = that.getConstraints(tv, ConstraintKind.EQUAL);
        if (inst.nonEmpty() && inst.head.tag != BOT) {
            uv.inst = inst.head;
        }
        uv.hibounds = hibounds.toList();
    }
    Type qtype1 = types.subst(that.qtype, that.tvars, undetvars);
    if (!types.isSubtype(qtype1,
            qtype1.tag == UNDETVAR ? types.boxedTypeOrType(to) : to)) {
        throw unambiguousNoInstanceException
            .setMessage("infer.no.conforming.instance.exists",
                        that.tvars, that.qtype, to);
    }
    for (List<Type> l = undetvars; l.nonEmpty(); l = l.tail)
        maximizeInst((UndetVar) l.head, warn);
    // System.out.println(" = " + qtype1.map(getInstFun));//DEBUG

    // check bounds
    List<Type> targs = Type.map(undetvars, getInstFun);
    if (Type.containsAny(targs, that.tvars)) {
        //replace uninferred type-vars
        targs = types.subst(targs,
                that.tvars,
                instaniateAsUninferredVars(undetvars, that.tvars));
    }
    return chk.checkType(warn.pos(), that.inst(targs, types), to);
}
 

import com.sun.tools.javac.code.Type.ForAll.ConstraintKind; //导入依赖的package包/类
@Override
public List<Type> getConstraints(TypeVar tv, ConstraintKind ck) {
    return UninferredMethodType.this.getConstraints(tv, ck);
}