Specialize type constraints

We were previously not specializing type constraints, which was
resulting in the constraint checking the unspecialized type parameter
type for compatibility with the specialized type, which would always
fail.

Author: fourls

delphi-frontend/src/main/java/au/com/integradev/delphi/type/generic/TypeSpecializationContextImpl.java

@@ -18,6 +18,7 @@
  */
 package au.com.integradev.delphi.type.generic;
 
+import au.com.integradev.delphi.type.generic.constraint.TypeConstraintImpl;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
@@ -28,6 +29,8 @@
 import org.sonar.plugins.communitydelphi.api.symbol.declaration.GenerifiableDeclaration;
 import org.sonar.plugins.communitydelphi.api.symbol.declaration.NameDeclaration;
 import org.sonar.plugins.communitydelphi.api.symbol.declaration.TypedDeclaration;
+import org.sonar.plugins.communitydelphi.api.type.Constraint;
+import org.sonar.plugins.communitydelphi.api.type.Constraint.TypeConstraint;
 import org.sonar.plugins.communitydelphi.api.type.Type;
 import org.sonar.plugins.communitydelphi.api.type.Type.TypeParameterType;
 import org.sonar.plugins.communitydelphi.api.type.TypeSpecializationContext;
@@ -66,14 +69,26 @@ public TypeSpecializationContextImpl(NameDeclaration declaration, List<Type> typ
     }
   }
 
-  private static boolean constraintViolated(Type parameter, Type argument) {
+  private boolean constraintViolated(Type parameter, Type argument) {
     return parameter.isTypeParameter()
         && ((TypeParameterType) parameter)
             .constraintItems().stream()
+                .map(this::specializeConstraint)
                 .map(constraint -> constraint.satisfiedBy(argument))
                 .anyMatch(s -> !s);
   }
 
+  private Constraint specializeConstraint(Constraint constraint) {
+    if (constraint instanceof TypeConstraint) {
+      Type specializedType = getArgument(((TypeConstraint) constraint).type());
+      if (specializedType != null) {
+        return new TypeConstraintImpl(specializedType);
+      }
+    }
+
+    return constraint;
+  }
+
   @Override
   @Nullable
   public Type getArgument(Type parameter) {

delphi-frontend/src/test/java/au/com/integradev/delphi/executor/DelphiSymbolTableExecutorTest.java

@@ -1100,7 +1100,8 @@ void testGenericImplicitSpecializations() {
   @Test
   void testGenericConstraints() {
     execute("generics/Constraint.pas");
-    verifyUsages(11, 14, reference(20, 25), reference(53, 8));
+    verifyUsages(11, 14, reference(20, 25), reference(58, 8));
+    verifyUsages(31, 20, reference(68, 8));
   }
 
   @Test

delphi-frontend/src/test/resources/au/com/integradev/delphi/symbol/generics/Constraint.pas

@@ -26,6 +26,11 @@    TFoo<T: ICloneable, TTest, ISerializable> = class
      procedure Test;
    end;
 
+   TMock = class(TObject)
+   public
+     class function Mock<I: IInterface; T: I>(out Raw: T): I;
+   end;
+
 implementation
 
 function TTest.SerializableClone: ISerializable;
@@ -60,4 +65,5 @@ procedure TFoo<T>.Test;
 initialization
   Foo := TFoo<TTest>.Create(Test);
   Foo.Test;
+  TMock.Mock<ISerializable, TTest>(Test);
 end.