FIR UAST: add support for multi resolve

plugins/kotlin/uast/uast-kotlin-fir/src/org/jetbrains/uast/kotlin/FirKotlinUastResolveProviderService.kt

@@ -185,6 +185,22 @@ interface FirKotlinUastResolveProviderService : BaseKotlinUastResolveProviderSer
         return psiElement.annotations
     }
 
+    override fun getReferenceVariants(ktExpression: KtExpression, nameHint: String): Sequence<PsiElement> {
+        analyzeForUast(ktExpression) {
+            return ktExpression.collectCallCandidates().asSequence().mapNotNull {
+                when (val candidate = it.candidate) {
+                    is KtFunctionCall<*> -> {
+                        toPsiMethod(candidate.partiallyAppliedSymbol.symbol, ktExpression)
+                    }
+                    is KtCompoundAccessCall -> {
+                        toPsiMethod(candidate.compoundAccess.operationPartiallyAppliedSymbol.symbol, ktExpression)
+                    }
+                    else -> null
+                }
+            }
+        }
+    }
+
     override fun resolveBitwiseOperators(ktBinaryExpression: KtBinaryExpression): UastBinaryOperator {
         val other = UastBinaryOperator.OTHER
         analyzeForUast(ktBinaryExpression) {

plugins/kotlin/uast/uast-kotlin-fir/src/org/jetbrains/uast/kotlin/internal/FirCliKotlinUastResolveProviderService.kt

@@ -3,14 +3,9 @@
 package org.jetbrains.uast.kotlin.internal
 
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.uast.kotlin.FirKotlinUastResolveProviderService
 
 class FirCliKotlinUastResolveProviderService : FirKotlinUastResolveProviderService {
     // Currently, UAST CLI is used by Android Lint, i.e., everything is a JVM element.
     override fun isJvmElement(psiElement: PsiElement): Boolean = true
-
-    override fun getReferenceVariants(ktExpression: KtExpression, nameHint: String): Sequence<PsiElement> {
-        return emptySequence() // Not supported (as per the counterpart [CliKotlinUastResolveProviderService])
-    }
 }

plugins/kotlin/uast/uast-kotlin-fir/test/org/jetbrains/kotlin/idea/fir/uast/FirUastResolveApiFixtureTest.kt

@@ -20,20 +20,12 @@ class FirUastResolveApiFixtureTest : KotlinLightCodeInsightFixtureTestCase(), Ua
         KotlinWithJdkAndRuntimeLightProjectDescriptor.getInstance()
 
     private val whitelist : Set<String> = setOf(
-        // TODO: multiResolve, getArgumentForParameter
-        "MultiResolve",
-        // TODO: multiResolve, getArgumentForParameter
-        "MultiResolveJava",
-        // TODO: multiResolve, getArgumentForParameter, return type for ambiguous call
+        // TODO: return type for ambiguous call
         "MultiResolveJavaAmbiguous",
-        // TODO: multiResolve
-        "MultiResolveInClass",
-        // TODO: multiResolve, return type for ambiguous call
+        // TODO: return type for ambiguous call
         "MultiConstructorResolve",
         // TODO: multiResolve
         "MultiInvokableObjectResolve",
-        // TODO: multiResolve
-        "MultiResolveJvmOverloads",
         // TODO: resolve annotation param to annotation ctor ??
         "ResolveCompiledAnnotation",
     )

plugins/kotlin/uast/uast-kotlin-idea-fir/src/org/jetbrains/uast/kotlin/internal/FirIdeaKotlinUastResolveProviderService.kt

@@ -3,14 +3,8 @@
 package org.jetbrains.uast.kotlin.internal
 
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.uast.kotlin.FirKotlinUastResolveProviderService
 
 class FirIdeaKotlinUastResolveProviderService : FirKotlinUastResolveProviderService {
     override fun isJvmElement(psiElement: PsiElement): Boolean = psiElement.isJvmElement
-
-    override fun getReferenceVariants(ktExpression: KtExpression, nameHint: String): Sequence<PsiElement> {
-        // TODO("Not yet implemented")
-        return emptySequence()
-    }
 }