FIR: Report UNSAFE_OPERATOR_CALL for augmented assignments (was

reporting UNSAFE_CALL).

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/augmentedAssignment.fir.kt

@@ -0,0 +1,17 @@
+class A {
+    operator fun plusAssign(s: String) {}
+}
+
+fun test() {
+    var a: A? = A()
+    a <!UNSAFE_OPERATOR_CALL!>+=<!> ""
+}
+
+class B {
+    operator fun plus(other: B) = this
+}
+
+fun test2() {
+    var b: B? = B()
+    b <!UNRESOLVED_REFERENCE!>+=<!> B()
+}

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/augmentedAssignment.kt

@@ -0,0 +1,17 @@
+class A {
+    operator fun plusAssign(s: String) {}
+}
+
+fun test() {
+    var a: A? = A()
+    a <!UNSAFE_OPERATOR_CALL!>+=<!> ""
+}
+
+class B {
+    operator fun plus(other: B) = this
+}
+
+fun test2() {
+    var b: B? = B()
+    b <!UNSAFE_OPERATOR_CALL!>+=<!> B()
+}

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/augmentedAssignment.txt

@@ -0,0 +1,20 @@
+package
+
+public fun test(): kotlin.Unit
+public fun test2(): kotlin.Unit
+
+public final class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun plusAssign(/*0*/ s: kotlin.String): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class B {
+    public constructor B()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun plus(/*0*/ other: B): B
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}