Reflection: support basic context parameters

 #KT-74529

Author: udalov

analysis/low-level-api-fir/tests-gen/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLBlackBoxTestGenerated.java

@@ -42,8 +42,12 @@ internal class KParameterState(
     override fun toString(): String {
         return buildString {
             when (kind) {
-                KParameter.Kind.EXTENSION_RECEIVER -> append("extension receiver parameter")
                 KParameter.Kind.INSTANCE -> append("instance parameter")
+                // Can't use `@OptIn(ExperimentalContextParameters::class)` as long as the project is compiled with API version 2.1.
+                @Suppress("OPT_IN_USAGE_ERROR")
+                KParameter.Kind.CONTEXT,
+                    -> append("context parameter ${irParameter.name}")
+                KParameter.Kind.EXTENSION_RECEIVER -> append("extension receiver parameter")
                 KParameter.Kind.VALUE -> append("parameter #$index ${irParameter.name}")
             }
 
@@ -57,4 +61,4 @@ internal class KParameterState(
             }
         }
     }
-}
+}

analysis/low-level-api-fir/tests-gen/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLReversedBlackBoxTestGenerated.java

@@ -0,0 +1,49 @@
+// LANGUAGE: +ContextParameters
+// OPT_IN: kotlin.ExperimentalContextParameters
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_K1: ANY
+// WITH_REFLECT
+
+import kotlin.reflect.*
+import kotlin.reflect.KParameter.Kind.*
+import kotlin.test.assertEquals
+
+interface A
+interface B
+interface C
+object D
+
+class Z {
+    context(a: A, b: B?)
+    fun C.f(d: D) {}
+
+    context(a: A, b: B?)
+    var C.p: D
+        get() = D
+        set(d) {}
+}
+
+fun checkABC(params: List<KParameter>) {
+    assertEquals(listOf(INSTANCE, CONTEXT, CONTEXT, EXTENSION_RECEIVER), params.map { it.kind })
+    assertEquals(listOf(null, "a", "b", null), params.map { it.name })
+    assertEquals(listOf(typeOf<Z>(), typeOf<A>(), typeOf<B?>(), typeOf<C>()), params.map { it.type })
+    assertEquals(params.indices.toList(), params.map { it.index })
+}
+
+fun checkABCD(params: List<KParameter>) {
+    assertEquals(listOf(INSTANCE, CONTEXT, CONTEXT, EXTENSION_RECEIVER, VALUE), params.map { it.kind })
+    assertEquals(listOf(null, "a", "b", null, "d"), params.map { it.name })
+    assertEquals(listOf(typeOf<Z>(), typeOf<A>(), typeOf<B?>(), typeOf<C>(), typeOf<D>()), params.map { it.type })
+    assertEquals(params.indices.toList(), params.map { it.index })
+}
+
+fun box(): String {
+    val f = Z::class.members.single { it.name == "f" }
+    checkABCD(f.parameters)
+
+    val p = Z::class.members.single { it.name == "p" } as KMutableProperty<*>
+    checkABC(p.parameters)
+    checkABC(p.getter.parameters)
+    checkABCD(p.setter.parameters)
+    return "OK"
+}

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenTestGenerated.java

@@ -1,5 +1,6 @@
+// LANGUAGE: +ContextParameters
 // TARGET_BACKEND: JVM
-
+// IGNORE_BACKEND_K1: JVM_IR
 // WITH_REFLECT
 
 import kotlin.test.*
@@ -17,12 +18,20 @@ class C : A()
 
 fun Int.extFun() {}
 
+class Z {
+    context(c: String)
+    fun context() {}
+}
+
 fun box(): String {
     assertEquals(listOf(false, false, true), A::foo.parameters.map { it.isOptional })
     assertEquals(listOf(false, false, true), B::foo.parameters.map { it.isOptional })
     assertEquals(listOf(false, false, true), C::foo.parameters.map { it.isOptional })
 
     assertFalse(Int::extFun.parameters.single().isOptional)
 
+    val context = Z::class.members.single { it.name == "context" }
+    assertEquals(listOf(false, false), context.parameters.map { it.isOptional })
+
     return "OK"
 }