[J2KT] Improve import resolver to preserve mapping between simple-nam…

…e and qualified-name, and use it for more precise import resolution.

PiperOrigin-RevId: 601248338

transpiler/java/com/google/j2cl/transpiler/backend/kotlin/Environment.kt

@@ -36,7 +36,6 @@ internal data class Environment(
   private val importedSimpleNameToQualifiedNameMutableMap: MutableMap<String, String> =
     mutableMapOf(),
   private val importedOptInQualifiedNamesMutableSet: MutableSet<String> = mutableSetOf(),
-  private val topLevelQualifiedNamesSet: Set<String> = setOf(),
 ) {
   /** Returns identifier for the given named node. */
   fun identifier(hasName: HasName): String =
@@ -70,15 +69,9 @@ internal data class Environment(
   /** Converts the given qualified name to non-aliased simple name, or null if alias is required. */
   fun qualifiedToNonAliasedSimpleName(qualifiedName: String): String? {
     val simpleName = qualifiedName.qualifiedNameToSimpleName()
-    if (topLevelQualifiedNamesSet.contains(qualifiedName)) {
-      return simpleName
-    }
     val importMap = importedSimpleNameToQualifiedNameMutableMap
     val importedQualifiedName = importMap[simpleName]
     if (importedQualifiedName == null) {
-      if (topLevelQualifiedNamesSet.any { it.qualifiedNameToSimpleName() == simpleName }) {
-        return null
-      }
       importMap[simpleName] = qualifiedName
       return simpleName
     }

transpiler/java/com/google/j2cl/transpiler/backend/kotlin/KotlinGeneratorStage.kt

@@ -70,10 +70,10 @@ class KotlinGeneratorStage(private val output: OutputUtils.Output, private val p
       Environment(
         nameToIdentifierMap = nameToIdentifierMap,
         identifierSet = nameToIdentifierMap.values.toSet(),
-        topLevelQualifiedNamesSet = compilationUnit.topLevelQualifiedNamesSet,
       )
 
-    val nameRenderer = NameRenderer(environment)
+    val nameRenderer =
+      NameRenderer(environment).plusLocalTypeNameMap(compilationUnit.localTypeNames)
 
     val compilationUnitRenderer = CompilationUnitRenderer(nameRenderer)
 

transpiler/java/com/google/j2cl/transpiler/backend/kotlin/NameRenderer.kt

@@ -17,6 +17,7 @@ package com.google.j2cl.transpiler.backend.kotlin
 
 import com.google.j2cl.transpiler.ast.DeclaredTypeDescriptor
 import com.google.j2cl.transpiler.ast.HasName
+import com.google.j2cl.transpiler.ast.Type
 import com.google.j2cl.transpiler.ast.TypeDescriptor
 import com.google.j2cl.transpiler.backend.kotlin.common.orIfNull
 import com.google.j2cl.transpiler.backend.kotlin.source.Source
@@ -25,14 +26,22 @@ import com.google.j2cl.transpiler.backend.kotlin.source.Source
  * Renderer of Kotlin names, with import resolution and alias generation.
  *
  * @property environment rendering environment
- * @property localNames a set of local names which are potentially shadowing imports
+ * @property localTypeNameMap a map from local names to qualified names
+ * @property localFieldNames a set of local field names
  */
 internal data class NameRenderer(
   val environment: Environment,
-  val localNames: Set<String> = setOf(),
+  val localTypeNameMap: Map<String, String> = mapOf(),
+  val localFieldNames: Set<String> = setOf(),
 ) {
-  fun plusLocalNames(localNames: Collection<String>): NameRenderer =
-    copy(localNames = this.localNames + localNames)
+  fun plusLocalNames(type: Type): NameRenderer =
+    plusLocalTypeNameMap(type.localTypeNameMap).plusLocalFieldNames(type.localFieldNames)
+
+  fun plusLocalTypeNameMap(localNameMap: Map<String, String>): NameRenderer =
+    copy(localTypeNameMap = this.localTypeNameMap + localNameMap)
+
+  fun plusLocalFieldNames(localNames: Set<String>): NameRenderer =
+    copy(localFieldNames = this.localFieldNames + localNames)
 
   /** Returns source containing name of the given node. */
   fun nameSource(hasName: HasName) = identifierSource(environment.identifier(hasName))
@@ -43,14 +52,36 @@ internal data class NameRenderer(
    * @param qualifiedName top-level qualified name
    */
   fun topLevelQualifiedNameSource(qualifiedName: String): Source =
+    topLevelSimpleNameOrNull(qualifiedName)
+      ?.let { identifierSource(it) }
+      .orIfNull { qualifiedIdentifierSource(qualifiedName) }
+
+  /**
+   * Returns simple name to use for the given top-level qualified name, or null if using simple name
+   * is not valid.
+   *
+   * @param qualifiedName top-level qualified name
+   * @return simple name or null
+   */
+  private fun topLevelSimpleNameOrNull(qualifiedName: String): String? =
     qualifiedName.qualifiedNameToSimpleName().let { simpleName ->
-      if (localNames.contains(simpleName) || environment.containsIdentifier(simpleName)) {
-        qualifiedIdentifierSource(qualifiedName)
-      } else {
-        environment
-          .qualifiedToNonAliasedSimpleName(qualifiedName)
-          ?.let { identifierSource(it) }
-          .orIfNull { qualifiedIdentifierSource(qualifiedName) }
+      when {
+        // Simple name shadowed by a field name.
+        localFieldNames.contains(simpleName) -> null
+
+        // Simple name shadowed by name in the environment.
+        environment.containsIdentifier(simpleName) -> null
+
+        // Look for local name, and use it if it refers to the same qualified name.
+        // Otherwise, take local name from environment, which will resolve imports.
+        else ->
+          localTypeNameMap[simpleName].let { localQualifiedName ->
+            if (localQualifiedName != null) {
+              simpleName.takeIf { localQualifiedName == qualifiedName }
+            } else {
+              environment.qualifiedToNonAliasedSimpleName(qualifiedName)
+            }
+          }
       }
     }
 

transpiler/java/com/google/j2cl/transpiler/backend/kotlin/Names.kt

@@ -28,17 +28,34 @@ import com.google.j2cl.transpiler.ast.TypeDeclaration
 import com.google.j2cl.transpiler.ast.TypeDescriptor
 import com.google.j2cl.transpiler.ast.Visibility
 
+/** Map entry from simple name to qualified name. */
+internal val TypeDeclaration.nameMapEntry: Pair<String, String>
+  get() = ktSimpleName to ktQualifiedName
+
+/** A map of member names used in this type. */
+internal val TypeDeclaration.memberTypeNameMap: Map<String, String>
+  get() = memberTypeDeclarations.mapNotNull { it.nameMapEntry }.let { mapOf(*it.toTypedArray()) }
+
+/** A map of local member names used in this type. */
+internal val TypeDeclaration.localTypeNameMap: Map<String, String>
+  get() = memberTypeNameMap.plus(nameMapEntry)
+
 /** A map of local names used in this type. */
-internal val Type.localTypeNames: Set<String>
-  get() = declaration.memberTypeDeclarations.mapNotNull { it.ktSimpleName }.toSet()
+internal val Type.localTypeNameMap: Map<String, String>
+  get() = declaration.localTypeNameMap
 
 /** A set of field names used in this type. */
 internal val Type.localFieldNames: Set<String>
   get() = fields.map { it.descriptor.ktName!! }.toSet()
 
 /** A set of top-level qualified name strings in this compilation unit. */
-internal val CompilationUnit.topLevelQualifiedNamesSet: Set<String>
-  get() = types.map { it.declaration }.filter { !it.isKtNative }.map { it.ktQualifiedName }.toSet()
+internal val CompilationUnit.localTypeNames: Map<String, String>
+  get() =
+    types
+      .map { it.declaration }
+      .filter { !it.isKtNative }
+      .map { it.ktSimpleName to it.ktQualifiedName }
+      .let { mapOf(*it.toTypedArray()) }
 
 /** Kotlin mangled name for this member descriptor. */
 internal val MemberDescriptor.ktMangledName: String

transpiler/java/com/google/j2cl/transpiler/backend/kotlin/TypeRenderer.kt

@@ -40,9 +40,6 @@ import com.google.j2cl.transpiler.backend.kotlin.source.orEmpty
  * @property nameRenderer underlying name renderer
  */
 internal data class TypeRenderer(val nameRenderer: NameRenderer) {
-  private fun NameRenderer.plusLocalNames(type: Type): NameRenderer =
-    plusLocalNames(type.localTypeNames).plusLocalNames(type.localFieldNames)
-
   private fun memberRenderer(type: Type): MemberRenderer =
     MemberRenderer(nameRenderer.plusLocalNames(type), type)