Fix handling of 'null' passed as C string (#3452)

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/cgen/CBridgeGen.kt

@@ -1375,8 +1375,10 @@ private class ObjCBlockPointerValuePassing(
 private class WCStringArgumentPassing : KotlinToCArgumentPassing {
 
     override fun KotlinToCCallBuilder.passValue(expression: IrExpression): CExpression {
-        val wcstr = irBuilder.irCall(symbols.interopWcstr.owner).apply {
-            extensionReceiver = expression
+        val wcstr = irBuilder.irSafeTransform(expression) {
+            irCall(symbols.interopWcstr.owner).apply {
+                extensionReceiver = it
+            }
         }
         return with(CValuesRefArgumentPassing) { passValue(wcstr) }
     }
@@ -1386,8 +1388,10 @@ private class WCStringArgumentPassing : KotlinToCArgumentPassing {
 private class CStringArgumentPassing : KotlinToCArgumentPassing {
 
     override fun KotlinToCCallBuilder.passValue(expression: IrExpression): CExpression {
-        val cstr = irBuilder.irCall(symbols.interopCstr.owner).apply {
-            extensionReceiver = expression
+        val cstr = irBuilder.irSafeTransform(expression) {
+            irCall(symbols.interopCstr.owner).apply {
+                extensionReceiver = it
+            }
         }
         return with(CValuesRefArgumentPassing) { passValue(cstr) }
     }
@@ -1410,25 +1414,33 @@ private fun KotlinToCCallBuilder.cValuesRefToPointer(
         value: IrExpression
 ): IrExpression = if (value.type.classifierOrNull == symbols.interopCPointer) {
     value // Optimization
-} else with(irBuilder) {
+} else {
     val getPointerFunction = symbols.interopCValuesRef.owner
             .simpleFunctions()
             .single { it.name.asString() == "getPointer" }
 
-    fun getPointer(expression: IrExpression) = irCall(getPointerFunction).apply {
-        dispatchReceiver = expression
-        putValueArgument(0, bridgeCallBuilder.getMemScope())
+    irBuilder.irSafeTransform(value) {
+        irCall(getPointerFunction).apply {
+            dispatchReceiver = it
+            putValueArgument(0, bridgeCallBuilder.getMemScope())
+        }
     }
+}
 
-    if (!value.type.isNullable()) {
-        getPointer(value) // Optimization
-    } else irLetS(value) { valueVarSymbol ->
+private fun IrBuilderWithScope.irSafeTransform(
+        value: IrExpression,
+        block: IrBuilderWithScope.(IrExpression) -> IrExpression
+): IrExpression = if (!value.type.isNullable()) {
+    block(value) // Optimization
+} else {
+    irLetS(value) { valueVarSymbol ->
         val valueVar = valueVarSymbol.owner
+        val transformed = block(irGet(valueVar))
         irIfThenElse(
-                type = symbols.interopCPointer.typeWithStarProjections.makeNullable(),
+                type = transformed.type.makeNullable(),
                 condition = irEqeqeq(irGet(valueVar), irNull()),
                 thenPart = irNull(),
-                elsePart = getPointer(irGet(valueVar))
+                elsePart = transformed
         )
     }
 }

backend.native/tests/build.gradle

@@ -3292,6 +3292,10 @@ createInterop("ctypes") {
     it.defFile 'interop/basics/ctypes.def'
 }
 
+createInterop("cvalues") {
+    it.defFile 'interop/basics/cvalues.def'
+}
+
 createInterop("ccallbacksAndVarargs") {
     it.defFile 'interop/basics/ccallbacksAndVarargs.def'
 }
@@ -3449,6 +3453,12 @@ interopTest("interop_types") {
     interop = 'ctypes'
 }
 
+interopTest("interop_values") {
+    disabled = (project.testTarget == 'wasm32') // No interop for wasm yet.
+    source = "interop/basics/values.kt"
+    interop = 'cvalues'
+}
+
 interopTest("interop_callbacksAndVarargs") {
     disabled = (project.testTarget == 'wasm32') // No interop for wasm yet.
     source = "interop/basics/callbacksAndVarargs.kt"

backend.native/tests/interop/basics/cvalues.def

@@ -0,0 +1,10 @@
+---
+_Bool isNullString(const char* str) {
+    return str == (const char*)0;
+}
+
+typedef const short* LPCWSTR;
+
+_Bool isNullWString(LPCWSTR str) {
+    return str == (LPCWSTR)0;
+}

backend.native/tests/interop/basics/values.kt

@@ -0,0 +1,10 @@
+import kotlinx.cinterop.*
+import kotlin.test.*
+import cvalues.*
+
+fun main() {
+    assertTrue(isNullString(null))
+    assertTrue(isNullWString(null))
+    assertFalse(isNullString("a"))
+    assertFalse(isNullWString("b"))
+}