rename 'add subtype/supertype constraint' methods:

supertype constraint means constraining type is a supertype of subject type (not vice versa)

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/CallResolver.java

@@ -374,8 +374,8 @@ public class CallResolver {
         }
 
         ConstraintSystem constraintSystemWithoutExpectedTypeConstraint = constraintSystem.copy();
-        constraintSystem.addSubtypingConstraint(descriptor.getReturnType(), context.expectedType,
-                                                 ConstraintPosition.EXPECTED_TYPE_POSITION);
+        constraintSystem.addSupertypeConstraint(descriptor.getReturnType(), context.expectedType,
+                                                ConstraintPosition.EXPECTED_TYPE_POSITION);
 
 
         if (!constraintSystem.isSuccessful()) {
@@ -761,8 +761,8 @@ public class CallResolver {
         ReceiverDescriptor receiverArgument = candidateCall.getReceiverArgument();
         ReceiverDescriptor receiverParameter = candidateWithFreshVariables.getReceiverParameter();
         if (receiverArgument.exists() && receiverParameter.exists()) {
-            constraintsSystem.addSupertypeConstraint(receiverParameter.getType(), receiverArgument.getType(),
-                                                     ConstraintPosition.RECEIVER_POSITION);
+            constraintsSystem.addSubtypeConstraint(receiverParameter.getType(), receiverArgument.getType(),
+                                                   ConstraintPosition.RECEIVER_POSITION);
         }
 
         ConstraintSystem constraintSystemWithRightTypeParameters = constraintsSystem.replaceTypeVariables(new Function<TypeParameterDescriptor, TypeParameterDescriptor>() {
@@ -816,7 +816,7 @@ public class CallResolver {
         else {
             type = null;
         }
-        constraintSystem.addSupertypeConstraint(effectiveExpectedType, type, ConstraintPosition.getValueParameterPosition(
+        constraintSystem.addSubtypeConstraint(effectiveExpectedType, type, ConstraintPosition.getValueParameterPosition(
                 valueParameterDescriptor.getIndex()));
         //todo no return
         if (isErrorType != null) {

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintSystem.java

@@ -42,22 +42,22 @@ public interface ConstraintSystem {
     Set<TypeParameterDescriptor> getTypeVariables();
 
     /**
-     * Adds a constraint that the subject type is a supertype of the constraining type.<p/>
+     * Adds a constraint that the constraining type is a subtype of the subject type.<p/>
      * Asserts that only subject type may contain registered type variables. <p/>
      *
      * For example, for {@code "fun <T> id(t: T) {}"} to infer <tt>T</tt> in invocation <tt>"id(1)"</tt>
-     * should be generated a constraint <tt>"T is a supertype of Int"</tt> where T is a subject type, and Int is a constraining type.
+     * should be generated a constraint <tt>"Int is a subtype of T"</tt> where T is a subject type, and Int is a constraining type.
      */
-    void addSupertypeConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
+    void addSubtypeConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
 
     /**
-     * Adds a constraint that subject type is a subtype of constraining type. <p/>
+     * Adds a constraint that the constraining type is a supertype of the subject type. <p/>
      * Asserts that only subject type may contain registered type variables. <p/>
      *
      * For example, for {@code "fun <T> create() : T"} to infer <tt>T</tt> in invocation <tt>"val i: Int = create()"</tt>
-     * should be generated a constraint <tt>"T is a subtype of Int"</tt> where T is a subject type, and Int is a constraining type.
+     * should be generated a constraint <tt>"Int is a supertype of T"</tt> where T is a subject type, and Int is a constraining type.
      */
-    void addSubtypingConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
+    void addSupertypeConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition);
 
     /**
      * Returns <tt>true</tt> if constraint system has a solution (has no contradiction and has enough information to infer each registered type variable).

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/inference/ConstraintSystemImpl.java

@@ -141,12 +141,20 @@ public class ConstraintSystemImpl implements ConstraintSystem {
     }
 
     @Override
-    public void addSubtypingConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition) {
+    public void addSupertypeConstraint(
+            @NotNull JetType subjectType,
+            @Nullable JetType constrainingType,
+            @NotNull ConstraintPosition constraintPosition
+    ) {
         addConstraint(SUB_TYPE, subjectType, constrainingType, constraintPosition);
     }
 
     @Override
-    public void addSupertypeConstraint(@NotNull JetType subjectType, @Nullable JetType constrainingType, @NotNull ConstraintPosition constraintPosition) {
+    public void addSubtypeConstraint(
+            @NotNull JetType subjectType,
+            @Nullable JetType constrainingType,
+            @NotNull ConstraintPosition constraintPosition
+    ) {
         addConstraint(SUPER_TYPE, subjectType, constrainingType, constraintPosition);
     }
 

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ExpressionTypingUtils.java

@@ -252,7 +252,7 @@ public class ExpressionTypingUtils {
             }
         }
 
-        constraintSystem.addSupertypeConstraint(callReceiver.getType(), receiverType, ConstraintPosition.RECEIVER_POSITION);
+        constraintSystem.addSubtypeConstraint(callReceiver.getType(), receiverType, ConstraintPosition.RECEIVER_POSITION);
         return constraintSystem.isSuccessful() && ConstraintsUtil.checkBoundsAreSatisfied(constraintSystem);
     }