Fix compilation of legacy default params on open function

Was broken because integration tests were disabled on prr/ branches.

Test: ComposeIT

Author: ShikaSD

plugins/compose/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/lower/ComposableFunctionBodyTransformer.kt

@@ -3081,7 +3081,7 @@ class ComposableFunctionBodyTransformer(
                     // ComposerParamTransformer should not allow for any null arguments on a composable
                     // invocation unless the parameter is vararg. If this is null here, we have
                     // missed something.
-                    error("Unexpected null argument for composable call")
+                    error("Unexpected null argument for composable call: ${expression.dump()}")
                 } else {
                     argsMeta.add(CallArgumentMeta(isVararg = true))
                     continue

plugins/compose/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/lower/ComposerParamTransformer.kt

@@ -427,7 +427,7 @@ class ComposerParamTransformer(
                 if (argIndex < newFn.parameters.size) {
                     newCall.arguments[argIndex++] = irConst(0)
                 } else {
-                    error("1. expected value parameter count to be higher: ${this.dumpSrc()}")
+                    error("expected \$сhanged parameter at index $argIndex:\n${newFn.dumpSrc()}")
                 }
             }
 
@@ -441,7 +441,7 @@ class ComposerParamTransformer(
                         .sliceArray(start until end)
                     newCall.arguments[argIndex++] = irConst(bitMask(*bits))
                 } else if (argumentsMissing.any { it }) {
-                    error("2. expected value parameter count to be higher: ${this.dumpSrc()}")
+                    error("expected \$default parameter at index $argIndex:\n${newFn.dumpSrc()}")
                 }
             }
         }
@@ -552,12 +552,24 @@ class ComposerParamTransformer(
 
     private fun IrSimpleFunction.requiresDefaultParameter(): Boolean =
         when {
+            // The function is a default parameter stub generated for backwards compatibility
             isDefaultParamStub -> true
+            // Same as above, but the method was generated by the old compiler, so $default parameter is needed for compatibility
+            isLegacyOpenFunctionWithDefault() -> true
+            // Virtual functions move default parameters into a wrapper
             isVirtualFunctionWithDefaultParam() -> false
+            // Fake overrides require default parameters if the original method is not virtual
             isFakeOverride -> overriddenSymbols.any { it.owner.modality == Modality.FINAL && it.owner.requiresDefaultParameter() }
+            // Regular functions also require default parameters
             else -> parameters.any { it.defaultValue != null }
         }
 
+    private fun IrSimpleFunction.isLegacyOpenFunctionWithDefault(): Boolean =
+        modality == Modality.OPEN && (
+                origin == IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB &&
+                        composeMetadata?.supportsOpenFunctionsWithDefaultParams() != true
+        ) || overriddenSymbols.any { it.owner.isLegacyOpenFunctionWithDefault() }
+
 
     private fun IrSimpleFunction.hasDefaultForParam(index: Int): Boolean {
         // checking for default value isn't enough, you need to ensure that none of the overrides