Reserve yield if it isn't function call.

compiler/testData/diagnostics/tests/ReserveYield.kt

@@ -0,0 +1,70 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_VARIABLE
+
+// FILE: 1.kt
+package p1.yield
+
+import p1.yield.yield
+import p1.yield.foo
+
+val yield = 5
+fun foo(){}
+
+fun bar(yield: Int = 4) {}
+
+fun yield(yield: Int) {
+    "$<!YIELD_IS_RESERVED!>yield<!>"
+    "${<!YIELD_IS_RESERVED!>yield<!>}"
+
+    <!YIELD_IS_RESERVED!>yield<!>
+    val foo = <!YIELD_IS_RESERVED!>yield<!> + <!YIELD_IS_RESERVED!>yield<!>
+    val foo2 = <!YIELD_IS_RESERVED!>yield<!>
+
+    bar(<!YIELD_IS_RESERVED!>yield<!> = 5)
+
+    yield(4)
+    <!YIELD_IS_RESERVED!>yield<!> {}
+
+    class yield<T: <!YIELD_IS_RESERVED!>yield<!><T>>
+
+    return@<!YIELD_IS_RESERVED!>yield<!>
+    return@<!YIELD_IS_RESERVED!>yield<!> Unit
+
+    val foo5: <!YIELD_IS_RESERVED!>yield<!><*>
+}
+
+fun yield(i: (Int) -> Unit) {}
+
+// FILE: 2.kt
+
+package p2.yield
+
+import p2.yield.yield
+import p2.yield.foo
+
+val yield = 5
+fun foo(){}
+
+fun bar(yield: Int = 4) {}
+
+fun yield(yield: Int) {
+    "$`yield`"
+    "${`yield`}"
+
+    `yield`
+    val foo = `yield` + `yield`
+    val foo2 = `yield`
+
+    bar(`yield` = 5)
+
+    `yield`(4)
+    `yield` {}
+
+    class `yield`<T: `yield`<T>>
+
+    return@`yield`
+    return@`yield` Unit
+
+    val foo5: `yield`<*>
+}
+
+fun yield(i: (Int) -> Unit) {}