[KT] Upgrade callable references before function inlining.

The J2clUpgradeCallableReferences pass is now run earlier in the lowering pipeline to ensure callable references are in the correct form before other passes, including function inlining.

Having `IrRichCallableReference` nodes in the IR tree before inlining allows for the removal of J2clInlineCallableReferenceToLambdaPhase and WrapInlineDeclarationsWithReifiedTypeParametersLowering.

We also need to run explicitly J2clUpgradeCallableReferences on inline function before the inlining. The serialized IR coming from Kotlin/JVM contains the old node to represent lambda and break their correct inlining.

PiperOrigin-RevId: 886825091

Author: jDramaix

transpiler/java/com/google/j2cl/transpiler/frontend/kotlin/lower/FunctionInlining.kt

@@ -97,6 +97,14 @@ constructor(
     if (actualCallee.body == null) {
       return expression
     }
+
+    // MODIFIED BY GOOGLE.
+    // The serialized IR from Kotlin/JVM compilation does not fully support
+    // `IrRichCallableReference` nodes. Run `J2clUpgradeCallableReferences` to ensure the inline
+    // function body uses the correct node types expected by the inliner.
+    J2clUpgradeCallableReferences(context).lower(actualCallee)
+    // END OF MODIFICATIONS.
+
     actualCallee.body?.transformChildren(this, actualCallee)
     actualCallee.parameters.forEachIndexed { index, param ->
       if (expression.arguments[index] == null) {
@@ -597,10 +605,9 @@ private class CallInlining(
             argumentExpression.isLambdaBlock())
 
     val isImmutableVariableLoad: Boolean
-      get() =
-        argumentExpression.let { argument ->
-          argument is IrGetValue && !argument.symbol.owner.let { it is IrVariable && it.isVar }
-        }
+      get() = argumentExpression.let { argument ->
+        argument is IrGetValue && !argument.symbol.owner.let { it is IrVariable && it.isVar }
+      }
   }
 
   private fun ParameterToArgument.allOuterClasses(): List<ParameterToArgument> {

transpiler/java/com/google/j2cl/transpiler/frontend/kotlin/lower/J2clUpgradeCallableReferences.kt

@@ -16,6 +16,7 @@
 
 package com.google.j2cl.transpiler.frontend.kotlin.lower
 
+import org.jetbrains.kotlin.backend.common.LoweringContext
 import org.jetbrains.kotlin.backend.common.lower.UpgradeCallableReferences
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.expressions.IrExpression
@@ -28,7 +29,7 @@ import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
 /** Upgrades property and function reference-like nodes to the new IrRichCallableReference node. */
-class J2clUpgradeCallableReferences(context: J2clBackendContext) :
+class J2clUpgradeCallableReferences(context: LoweringContext) :
   UpgradeCallableReferences(
     context,
     upgradeFunctionReferencesAndLambdas = true,

transpiler/java/com/google/j2cl/transpiler/frontend/kotlin/lower/LoweringPasses.kt

@@ -73,11 +73,11 @@ private val loweringPhase = loweringPhase {
   // Invent names for local classes and anonymous objects. Later passes may require all classes
   // to have a name for computing function signature.
   perFileLowering(jvmInventNamesForLocalClassesFactory)
-  // Transform all callable reference (including defaults) to inline lambdas, mark inline lambdas
-  // for later passes.
-  perFileLowering(::J2clInlineCallableReferenceToLambdaPhase)
   // Rewrites `Array(size) { index -> value }` using type-specific initializer lambdas.
   perFileLowering(::ArrayConstructorLowering)
+  // TODO(dramaix) : This should be run as the first pass. But our inlining pass is adding function
+  // references and function expression.
+  moduleLowering(::J2clUpgradeCallableReferences)
   // Create nullable backing fields and insert nullability checks for lateinit properties and
   // variables. Must run before JvmPropertiesLowering.
   perFileLowering(::LateinitLowering)
@@ -89,21 +89,8 @@ private val loweringPhase = loweringPhase {
   perFileLowering(::LocalClassesExtractionFromInlineFunctionsLowering.asPostfix())
   // Create public bridge for private top level function called from inline functions.
   perFileLowering(::SyntheticAccessorLowering)
-  // TODO(b/449125803) : remove that pass and use `UpgradeCallableReferences` instead.
-  // Replace reference to inline function with reified parameter with reference to a synthetic
-  // non-inline function where types parameters have been substituted so there is no reference to
-  // inline functions anymore.
-  // ex:
-  // inline fun <reified T> castTo(param: Any): T  = param as T
-  // reference like `::castTo<String>` is replaced with `::castTo$wrap` where
-  // fun castTo$wrap(param: Any) String = castTo<String>(param)
-  perFileLowering(::WrapInlineDeclarationsWithReifiedTypeParametersLowering)
   // Perform function inlining.
   moduleLowering(::J2clFunctionInlining)
-  // TODO(dramaix) : This should be run as the first pass. But our inlining pass is adding function
-  // references and function expression.
-  moduleLowering(::J2clUpgradeCallableReferences)
-
   // Remove inline functions with reified type parameters as these functions cannot be called from
   // Java
   perFileLowering(::RemoveInlineDeclarationsWithReifiedTypeParametersLowering)

transpiler/javatests/com/google/j2cl/readable/kotlin/localfunction/output_closure/LocalFunctionKt.impl.java.js.txt

@@ -90,16 +90,16 @@ class LocalFunctionKt extends j_l_Object {
  }
  /** @nodts @return {string} */
  static m_localFunctionInInlinedLambda__java_lang_String() {
-  let tmp0__this_ = StringBuilder.$create__();
-  let this_1 = tmp0__this_;
-  let appendTwoDigits = (/** !Appendable */ this_2, /** number */ number_1) =>{
+  let anonymous_$appendTwoDigit = (/** !Appendable */ this_1, /** !StringBuilder */ $this_apply, /** number */ number_1) =>{
    if (number_1 < 10) {
-    this_2.m_append__char__java_lang_Appendable(48 /* '0' */);
+    this_1.m_append__char__java_lang_Appendable(48 /* '0' */);
    }
-   this_1.m_append__int__java_lang_StringBuilder(number_1);
+   $this_apply.m_append__int__java_lang_StringBuilder(number_1);
   };
-  appendTwoDigits(this_1, 1);
-  return InternalPreconditions.m_checkNotNull__java_lang_Object__java_lang_Object(this_1.toString());
+  let tmp0__this_ = StringBuilder.$create__();
+  let this_2 = tmp0__this_;
+  anonymous_$appendTwoDigit(this_2, this_2, 1);
+  return InternalPreconditions.m_checkNotNull__java_lang_Object__java_lang_Object(this_2.toString());
  }
  /** @nodts @template T @return {string} */
  static m_localFunctionWithGenericType__java_lang_Object__java_lang_String(/** T */ t) {