Extension functions & inference.

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemBuilderImpl.kt

@@ -17,6 +17,7 @@
 package org.jetbrains.kotlin.resolve.calls.inference
 
 import org.jetbrains.kotlin.builtins.createFunctionType
+import org.jetbrains.kotlin.builtins.isBuiltinExtensionFunctionalType
 import org.jetbrains.kotlin.builtins.isExtensionFunctionType
 import org.jetbrains.kotlin.builtins.isSuspendFunctionType
 import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
@@ -435,7 +436,7 @@ internal fun createTypeForFunctionPlaceholder(
 
     val functionPlaceholderTypeConstructor = functionPlaceholder.constructor as FunctionPlaceholderTypeConstructor
 
-    val isExtension = expectedType.isExtensionFunctionType
+    val isExtension = expectedType.isBuiltinExtensionFunctionalType
     val newArgumentTypes = if (!functionPlaceholderTypeConstructor.hasDeclaredArguments) {
         val typeParamSize = expectedType.constructor.parameters.size
         // the first parameter is receiver (if present), the last one is return type,

compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference3.kt

@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> withS(x: T, sfn: suspend T.() -> Unit) = x
+
+val test1 = withS(100) {}
+
+fun <TT> test2(x: TT) = withS(x) {}

compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference3.txt

@@ -0,0 +1,5 @@
+package
+
+public val test1: kotlin.Int
+public fun </*0*/ TT> test2(/*0*/ x: TT): TT
+public fun </*0*/ T> withS(/*0*/ x: T, /*1*/ sfn: suspend T.() -> kotlin.Unit): T

compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference4.kt

@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T1, T2> withS2(x: T1, sfn1: suspend T1.() -> T2, sfn2: suspend T2.() -> Unit): T2 = null!!
+
+val test1 = withS2(100, { toLong().toString() }, { length })

compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference4.txt

@@ -0,0 +1,4 @@
+package
+
+public val test1: kotlin.String
+public fun </*0*/ T1, /*1*/ T2> withS2(/*0*/ x: T1, /*1*/ sfn1: suspend T1.() -> T2, /*2*/ sfn2: suspend T2.() -> kotlin.Unit): T2

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -4431,6 +4431,18 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("inference3.kt")
+                public void testInference3() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference3.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("inference4.kt")
+                public void testInference4() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/inference4.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("lambdaInOverriddenValInitializer.kt")
                 public void testLambdaInOverriddenValInitializer() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/coroutines/suspendFunctionType/lambdaInOverriddenValInitializer.kt");

core/descriptors/src/org/jetbrains/kotlin/builtins/functionTypes.kt

@@ -87,9 +87,12 @@ fun isBuiltinFunctionClass(classId: ClassId): Boolean {
 }
 
 val KotlinType.isNonExtensionFunctionType: Boolean
-    get() = isBuiltinFunctionalType && !isTypeAnnotatedWithExtensionFunctionType
+    get() = isFunctionType && !isTypeAnnotatedWithExtensionFunctionType
 
 val KotlinType.isExtensionFunctionType: Boolean
+    get() = isFunctionType && isTypeAnnotatedWithExtensionFunctionType
+
+val KotlinType.isBuiltinExtensionFunctionalType: Boolean
     get() = isBuiltinFunctionalType && isTypeAnnotatedWithExtensionFunctionType
 
 private val KotlinType.isTypeAnnotatedWithExtensionFunctionType: Boolean
@@ -137,7 +140,7 @@ fun KotlinType.getReturnTypeFromFunctionType(): KotlinType {
 fun KotlinType.getValueParameterTypesFromFunctionType(): List<TypeProjection> {
     assert(isBuiltinFunctionalType) { "Not a function type: ${this}" }
     val arguments = arguments
-    val first = if (isExtensionFunctionType) 1 else 0
+    val first = if (isBuiltinExtensionFunctionalType) 1 else 0
     val last = arguments.size - 1
     assert(first <= last) { "Not an exact function type: ${this}" }
     return arguments.subList(first, last)