Expose APIs to tell if a method param is synthetic.

Test: tested with XExecutableElementTest
Change-Id: I095d57a2f01c13d88d126952cca0767becf08067

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/XExecutableParameterElement.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/XExecutableParameterElement.kt
index b5148d4..8454bd9 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/XExecutableParameterElement.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/XExecutableParameterElement.kt

@@ -20,6 +20,21 @@
  * Parameter of a method.
  */
 interface XExecutableParameterElement : XVariableElement {
+    /**
+     * Returns `true` if this parameter is a synthetic Continuation parameter of a suspend function.
+     */
+    fun isContinuationParam(): Boolean
+
+    /**
+     * Returns `true` if this parameter represents the receiver of an extension function.
+     */
+    fun isReceiverParam(): Boolean
+
+    /**
+     * Returns `true` if this parameter represents the single parameter of a Kotlin property setter
+     * method.
+     */
+    fun isKotlinPropertyParam(): Boolean
 
     /**
      * The enclosing [XExecutableElement] this parameter belongs to.

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/javac/JavacMethodParameter.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/javac/JavacMethodParameter.kt
index 27aeaa5..88fe3b7 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/javac/JavacMethodParameter.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/javac/JavacMethodParameter.kt

@@ -30,6 +30,19 @@
     kotlinMetadataFactory: () -> KmValueParameterContainer?,
     val argIndex: Int
 ) : JavacVariableElement(env, element), XExecutableParameterElement {
+    override fun isContinuationParam() =
+        enclosingElement is JavacMethodElement &&
+        enclosingElement.isSuspendFunction() &&
+        enclosingElement.parameters.last() == this
+
+    override fun isReceiverParam() =
+        enclosingElement is JavacMethodElement &&
+        enclosingElement.isExtensionFunction() &&
+        enclosingElement.parameters.first() == this
+
+    override fun isKotlinPropertyParam() =
+        enclosingElement is JavacMethodElement &&
+        enclosingElement.isKotlinPropertyMethod()
 
     override val kotlinMetadata by lazy { kotlinMetadataFactory() }
 

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/KspExecutableParameterElement.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/KspExecutableParameterElement.kt
index 8a6ed9a..fe11246 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/KspExecutableParameterElement.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/KspExecutableParameterElement.kt

@@ -36,6 +36,11 @@
 ) : KspElement(env, parameter),
     XExecutableParameterElement,
     XAnnotated by KspAnnotated.create(env, parameter, NO_USE_SITE_OR_METHOD_PARAMETER) {
+    override fun isContinuationParam() = false
+
+    override fun isReceiverParam() = false
+
+    override fun isKotlinPropertyParam() = false
 
     override val name: String
         get() = parameter.name?.asString() ?: "_no_param_name"

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticContinuationParameterElement.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticContinuationParameterElement.kt
index 620f91f..447fbf3 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticContinuationParameterElement.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticContinuationParameterElement.kt

@@ -48,6 +48,11 @@
         delegate = null, // does not matter, this is synthetic and has no annotations.
         filter = NO_USE_SITE
     ) {
+    override fun isContinuationParam() = true
+
+    override fun isReceiverParam() = false
+
+    override fun isKotlinPropertyParam() = false
 
     override val name: String by lazy {
         // KAPT uses `continuation` but it doesn't check for conflicts, we do.

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticPropertyMethodElement.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticPropertyMethodElement.kt
index d6bf00e..ec5190d 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticPropertyMethodElement.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticPropertyMethodElement.kt

@@ -232,6 +232,11 @@
                 delegate = enclosingElement.field.declaration.setter?.parameter,
                 filter = NO_USE_SITE_OR_SET_PARAM
             ) {
+            override fun isContinuationParam() = false
+
+            override fun isReceiverParam() = false
+
+            override fun isKotlinPropertyParam() = true
 
             private val jvmTypeResolutionScope = KspJvmTypeResolutionScope.PropertySetterParameter(
                 declaration = enclosingElement
@@ -323,4 +328,4 @@
             }
         }
     }
-}
\ No newline at end of file
+}

diff --git a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticReceiverParameterElement.kt b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticReceiverParameterElement.kt
index 1c7bf1e..acef3af 100644
--- a/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticReceiverParameterElement.kt
+++ b/room/room-compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/synthetic/KspSyntheticReceiverParameterElement.kt

@@ -42,6 +42,12 @@
         filter = KspAnnotated.UseSiteFilter.NO_USE_SITE
     ) {
 
+    override fun isContinuationParam() = false
+
+    override fun isReceiverParam() = true
+
+    override fun isKotlinPropertyParam() = false
+
     override val name: String by lazy {
         // KAPT uses `$this$<functionName>`
         "$" + "this" + "$" + enclosingElement.name

diff --git a/room/room-compiler-processing/src/test/java/androidx/room/compiler/processing/XExecutableElementTest.kt b/room/room-compiler-processing/src/test/java/androidx/room/compiler/processing/XExecutableElementTest.kt
index 73c87b1..91ff9e3 100644
--- a/room/room-compiler-processing/src/test/java/androidx/room/compiler/processing/XExecutableElementTest.kt
+++ b/room/room-compiler-processing/src/test/java/androidx/room/compiler/processing/XExecutableElementTest.kt

@@ -445,6 +445,7 @@
                     assertThat(method.parameters.first().type.asTypeName()).isEqualTo(
                         String::class.asClassName()
                     )
+                    assertThat(method.parameters.first().isKotlinPropertyParam()).isTrue()
                     assertThat(method.isPublic()).isTrue()
                     assertThat(method.parameters.first().type.nullability).isEqualTo(
                         XNullability.NONNULL
@@ -986,6 +987,7 @@
                 element.getDeclaredMethodByJvmName("ext1").let { method ->
                     assertThat(method.isExtensionFunction()).isTrue()
                     assertThat(method.parameters.size).isEqualTo(1)
+                    assertThat(method.parameters[0].isReceiverParam()).isTrue()
                     assertThat(method.parameters[0].name).isEqualTo("\$this\$ext1")
                     assertThat(method.parameters[0].type.asTypeName())
                         .isEqualTo(String::class.asClassName())
@@ -1028,6 +1030,7 @@
                     assertThat(method.parameters.size).isEqualTo(2)
                     assertThat(method.parameters[0].type.asTypeName())
                         .isEqualTo(String::class.asClassName())
+                    assertThat(method.parameters[1].isContinuationParam()).isTrue()
                     assertThat(method.parameters[1].type.typeName).isEqualTo(
                         ParameterizedTypeName.get(
                             ClassName.get("kotlin.coroutines", "Continuation"),