[Interop] Add test for different types of struct fields

backend.native/tests/build.gradle

@@ -3345,6 +3345,10 @@ createInterop("cvalues") {
     it.defFile 'interop/basics/cvalues.def'
 }
 
+createInterop("cstructs") {
+    it.defFile 'interop/basics/cstructs.def'
+}
+
 createInterop("ccallbacksAndVarargs") {
     it.defFile 'interop/basics/ccallbacksAndVarargs.def'
 }
@@ -3520,6 +3524,12 @@ interopTest("interop_values") {
     interop = 'cvalues'
 }
 
+interopTest("interop_structs") {
+    disabled = (project.testTarget == 'wasm32') // No interop for wasm yet.
+    source = "interop/basics/structs.kt"
+    interop = 'cstructs'
+}
+
 interopTest("interop_callbacksAndVarargs") {
     disabled = (project.testTarget == 'wasm32') // No interop for wasm yet.
     source = "interop/basics/callbacksAndVarargs.kt"

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

@@ -0,0 +1,33 @@
+---
+typedef float __attribute__ ((__vector_size__ (16)))   KVector4f;
+
+typedef struct {
+    int i;
+} Trivial;
+
+enum E {
+    R, G, B
+};
+
+struct Complex {
+    unsigned int ui;
+    KVector4f vec4f;
+    Trivial t;
+    struct Complex* next;
+    enum E e;
+    int arr[2];
+};
+
+struct Complex produceComplex() {
+    struct Complex complex;
+    complex.ui = 128;
+    KVector4f vec = { 1.0, 1.0, 1.0, 1.0 };
+    complex.vec4f = vec;
+    Trivial t = { .i = 1 };
+    complex.t = t;
+    complex.next = 0;
+    complex.e = R;
+    complex.arr[0] = -51;
+    complex.arr[1] = -19;
+    return complex;
+};

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

@@ -0,0 +1,34 @@
+import cstructs.*
+import kotlinx.cinterop.*
+import kotlin.test.*
+
+fun main() {
+    produceComplex().useContents {
+        assertEquals(ui, 128u)
+        ui = 333u
+        assertEquals(ui, 333u)
+
+        assertEquals(t.i, 1)
+        t.i += 15
+        assertEquals(t.i, 16)
+
+        assertEquals(next, null)
+        next = this.ptr
+        assertEquals(next, this.ptr)
+
+        assertEquals(vec4f, vectorOf(1.0f, 1.0f, 1.0f, 1.0f))
+        vec4f = vectorOf(0.0f, 0.0f, 0.0f, 0.0f)
+        assertEquals(vec4f, vectorOf(0.0f, 0.0f, 0.0f, 0.0f))
+
+        assertEquals(e, E.R)
+        e = E.G
+        assertEquals(e, E.G)
+
+        assertEquals(arr[0], -51)
+        assertEquals(arr[1], -19)
+        arr[0] = 51
+        arr[1] = 19
+        assertEquals(arr[0], 51)
+        assertEquals(arr[1], 19)
+    }
+}