Forbidden old invokeExtension convention.

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -453,8 +453,6 @@ public interface Errors {
     DiagnosticFactory1<JetExpression, JetType> MISSING_RECEIVER = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory0<JetExpression> NO_RECEIVER_ALLOWED = DiagnosticFactory0.create(ERROR);
 
-    DiagnosticFactory0<JetExpression> FREE_FUNCTION_CALLED_AS_EXTENSION = DiagnosticFactory0.create(ERROR);
-
     // Call resolution
 
     DiagnosticFactory1<JetExpression, String> ILLEGAL_SELECTOR = DiagnosticFactory1.create(ERROR);
@@ -475,6 +473,7 @@ public interface Errors {
     DiagnosticFactory1<PsiElement, Collection<? extends ResolvedCall<?>>> NONE_APPLICABLE = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, Collection<? extends ResolvedCall<?>>> CANNOT_COMPLETE_RESOLVE = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, Collection<? extends ResolvedCall<?>>> UNRESOLVED_REFERENCE_WRONG_RECEIVER = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<PsiElement, JetExpression> INVOKE_EXTENSION_ON_NOT_EXTENSION_FUNCTION = DiagnosticFactory1.create(ERROR);
 
     DiagnosticFactory1<PsiElement, TypeParameterDescriptor> TYPE_PARAMETER_AS_REIFIED = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, JetType> REIFIED_TYPE_FORBIDDEN_SUBSTITUTION = DiagnosticFactory1.create(ERROR);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -591,13 +591,12 @@ public class DefaultErrorMessages {
         MAP.put(NONE_APPLICABLE, "None of the following functions can be called with the arguments supplied: {0}", AMBIGUOUS_CALLS);
         MAP.put(CANNOT_COMPLETE_RESOLVE, "Cannot choose among the following candidates without completing type inference: {0}", AMBIGUOUS_CALLS);
         MAP.put(UNRESOLVED_REFERENCE_WRONG_RECEIVER, "Unresolved reference. None of the following candidates is applicable because of receiver type mismatch: {0}", AMBIGUOUS_CALLS);
+        MAP.put(INVOKE_EXTENSION_ON_NOT_EXTENSION_FUNCTION, "Impossible call as extension because {0} is not an extension function.", ELEMENT_TEXT);
 
         MAP.put(NO_VALUE_FOR_PARAMETER, "No value passed for parameter {0}", NAME);
         MAP.put(MISSING_RECEIVER, "A receiver of type {0} is required", RENDER_TYPE);
         MAP.put(NO_RECEIVER_ALLOWED, "No receiver can be passed to this function or property");
 
-        MAP.put(FREE_FUNCTION_CALLED_AS_EXTENSION, "The function cannot be called as an extension function");
-
         MAP.put(CREATING_AN_INSTANCE_OF_ABSTRACT_CLASS, "Cannot create an instance of an abstract class");
 
         MAP.put(TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS, "Type inference failed: {0}", TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS_RENDERER);

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CandidateResolver.kt

@@ -267,14 +267,18 @@ public class CandidateResolver(
     }
 
     private fun CallCandidateResolutionContext<*>.checkNonExtensionCalledWithReceiver() = checkAndReport {
-        if (isSynthesizedInvoke(candidateCall.getCandidateDescriptor())
-            && !KotlinBuiltIns.isExtensionFunctionType(candidateCall.getDispatchReceiver().getType())
+        val call = candidateCall.call
+        if (call is CallTransformer.CallForImplicitInvoke && candidateCall.extensionReceiver.exists()
+                && candidateCall.dispatchReceiver.exists()
         ) {
-            tracing.freeFunctionCalledAsExtension(trace)
-            OTHER_ERROR
-        } else {
-            SUCCESS
+            if (call.dispatchReceiver == candidateCall.dispatchReceiver
+                    && !KotlinBuiltIns.isExactExtensionFunctionType(call.dispatchReceiver.type)
+            ) {
+                tracing.nonExtensionFunctionCalledAsExtension(trace)
+                return@checkAndReport OTHER_ERROR
+            }
         }
+        SUCCESS
     }
 
     private fun getReceiverSuper(receiver: ReceiverValue): JetSuperExpression? {

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/AbstractTracingStrategy.java

@@ -253,7 +253,7 @@ public abstract class AbstractTracingStrategy implements TracingStrategy {
     }
 
     @Override
-    public void freeFunctionCalledAsExtension(@NotNull BindingTrace trace) {
-        trace.report(FREE_FUNCTION_CALLED_AS_EXTENSION.on(reference));
+    public void nonExtensionFunctionCalledAsExtension(@NotNull BindingTrace trace) {
+        trace.report(INVOKE_EXTENSION_ON_NOT_EXTENSION_FUNCTION.on(reference, reference));
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/TracingStrategy.java

@@ -101,7 +101,7 @@ public interface TracingStrategy {
         public void typeInferenceFailed(@NotNull BindingTrace trace, @NotNull InferenceErrorData inferenceErrorData) {}
 
         @Override
-        public void freeFunctionCalledAsExtension(@NotNull BindingTrace trace) { }
+        public void nonExtensionFunctionCalledAsExtension(@NotNull BindingTrace trace) { }
     };
 
     void bindCall(@NotNull BindingTrace trace, @NotNull Call call);
@@ -153,5 +153,5 @@ public interface TracingStrategy {
 
     void typeInferenceFailed(@NotNull BindingTrace trace, @NotNull InferenceErrorData inferenceErrorData);
 
-    void freeFunctionCalledAsExtension(@NotNull BindingTrace trace);
+    void nonExtensionFunctionCalledAsExtension(@NotNull BindingTrace trace);
 }

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/ControlStructureTypingUtils.java

@@ -534,7 +534,7 @@ public class ControlStructureTypingUtils {
         }
 
         @Override
-        public void freeFunctionCalledAsExtension(@NotNull BindingTrace trace) {
+        public void nonExtensionFunctionCalledAsExtension(@NotNull BindingTrace trace) {
             logError();
         }
     }