Smart casts for local variables not captured in a closure and not changed in a loop, see #KT-3175.

isLocalVariable added. Assignment / initialization analysis.
Control whether a variable is changed in a loop at the beginning and at the end of the loop.
Control whether a variable is captured in a closure. #KT-3175  Fixed. #KT-2266  Fixed.
Tests for variable null safety and for variables is/as operations.
Loop / closure / variable property tests are included.
Old tests changed in accordance with KT-3175. In particular, all three of testSmartcastImpossible were fixed.

compiler/testData/diagnostics/tests/smartCasts/variables/assignment.kt

@@ -0,0 +1,10 @@
+fun foo() {
+    var v: Any = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = "abc"
+    <!DEBUG_INFO_SMARTCAST!>v<!>.length()
+    v = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = "abc"
+    <!DEBUG_INFO_SMARTCAST!>v<!>.length()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/assignment.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.kt

@@ -0,0 +1,12 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: Any): Int {
+    var p = pp
+    do {
+        (p as String).length()
+        if (p == "abc") break
+        p = 42
+    } while (!x())
+    // Smart cast is NOT possible here
+    return p.<!UNRESOLVED_REFERENCE!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.txt

@@ -0,0 +1,4 @@
+package
+
+public fun foo(/*0*/ pp: kotlin.Any): kotlin.Int
+internal fun x(): kotlin.Boolean

compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhile.kt

@@ -0,0 +1,15 @@
+public fun foo(xx: Any): Int {
+    var x = xx
+    do {
+        var y: Any
+        // After the check, smart cast should work
+        if (x is String) {
+            y = "xyz"
+        } else {
+            y = "abc"
+        }
+        // y!! in both branches
+        <!DEBUG_INFO_SMARTCAST!>y<!>.length()
+    } while (!(x is String))
+    return <!DEBUG_INFO_SMARTCAST!>x<!>.length()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhile.txt

@@ -0,0 +1,3 @@
+package
+
+public fun foo(/*0*/ xx: kotlin.Any): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.kt

@@ -0,0 +1,16 @@
+public fun foo(xx: Any): Int {
+    var x = xx
+    do {
+        var y: Any
+        // After the check, smart cast should work
+        if (x is String) {
+            break
+        } else {
+            y = "abc"
+        }
+        // y!! in both branches
+        <!DEBUG_INFO_SMARTCAST!>y<!>.length()
+    } while (true)
+    // We could have smart cast here but with break it's hard to detect
+    return x.<!UNRESOLVED_REFERENCE!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.txt

@@ -0,0 +1,3 @@
+package
+
+public fun foo(/*0*/ xx: kotlin.Any): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIs.kt

@@ -0,0 +1,9 @@
+public fun bar(s: String) {
+    System.out.println("Length of $s is ${s.length()}")
+}
+
+public fun foo() {
+    var s: Any = "not null"
+    if (s is String) 
+        bar(<!DEBUG_INFO_SMARTCAST!>s<!>)
+}

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIs.txt

@@ -0,0 +1,4 @@
+package
+
+public fun bar(/*0*/ s: kotlin.String): kotlin.Unit
+public fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsAnd.kt

@@ -0,0 +1,13 @@
+// See KT-5737
+fun get(): Any {
+    return "abc"
+}
+
+fun foo(): Int {
+    var ss: Any = get()
+
+    return if (ss is String && <!DEBUG_INFO_SMARTCAST!>ss<!>.length() > 0)
+        1
+    else
+        0
+}

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsAnd.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun foo(): kotlin.Int
+internal fun get(): kotlin.Any

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsChanged.kt

@@ -0,0 +1,11 @@
+public fun bar(s: String) {
+    System.out.println("Length of $s is ${s.length()}")
+}
+
+public fun foo() {
+    var s: Any = "not null"
+    if (s is String) {
+        s = 42
+        bar(<!TYPE_MISMATCH!>s<!>)
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsChanged.txt

@@ -0,0 +1,4 @@
+package
+
+public fun bar(/*0*/ s: kotlin.String): kotlin.Unit
+public fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/infix.kt

@@ -0,0 +1,11 @@
+// See KT-774
+fun box() : Int {
+    var a : Any = 1
+    var d = 1
+
+    if (a is Int) {
+        return <!DEBUG_INFO_SMARTCAST!>a<!> + d
+    } else {
+        return 2
+    }
+} 

compiler/testData/diagnostics/tests/smartCasts/variables/infix.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun box(): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/variables/initialization.kt

@@ -0,0 +1,8 @@
+fun foo() {
+    var v: Any = "xyz"
+    // It is possible in principle to provide smart cast here
+    // but now we decide that v is Any
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/initialization.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/property.kt

@@ -0,0 +1,10 @@
+class MyClass(var p: String?)
+
+fun bar(s: String): Int {
+    return s.length()
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(<!SMARTCAST_IMPOSSIBLE!>m.p<!>)
+}

compiler/testData/diagnostics/tests/smartCasts/variables/property.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun bar(/*0*/ s: kotlin.String): kotlin.Int
+internal fun foo(/*0*/ m: MyClass): kotlin.Int
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ p: kotlin.String?)
+    internal final var p: kotlin.String?
+    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 open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertyNotNeeded.kt

@@ -0,0 +1,10 @@
+class MyClass(var p: String?)
+
+fun bar(s: String?): Int {
+    return s?.length() ?: -1
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(m.p)
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertyNotNeeded.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun bar(/*0*/ s: kotlin.String?): kotlin.Int
+internal fun foo(/*0*/ m: MyClass): kotlin.Int
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ p: kotlin.String?)
+    internal final var p: kotlin.String?
+    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 open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtype.kt

@@ -0,0 +1,10 @@
+class MyClass(var p: Any)
+
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(m.p)
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtype.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun bar(/*0*/ s: kotlin.Any): kotlin.Int
+internal fun foo(/*0*/ m: MyClass): kotlin.Int
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ p: kotlin.Any)
+    internal final var p: kotlin.Any
+    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 open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMember.kt

@@ -0,0 +1,10 @@
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+class MyClass(var p: Any) {
+    fun foo(): Int {
+        p = "xyz"
+        return bar(p)
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMember.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun bar(/*0*/ s: kotlin.Any): kotlin.Int
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ p: kotlin.Any)
+    internal final var p: kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    internal final fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMemberCheck.kt

@@ -0,0 +1,13 @@
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+class MyClass(var p: Any) {
+    fun foo(): Int {
+        p = "xyz"
+        if (p is String) {
+            return bar(p)
+        }
+        return -1
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMemberCheck.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun bar(/*0*/ s: kotlin.Any): kotlin.Int
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ p: kotlin.Any)
+    internal final var p: kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    internal final fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/variables/varAsUse.kt

@@ -0,0 +1,9 @@
+fun get(): Any {
+    return ""
+}
+
+fun foo(): Int {
+    var c: Any = get()
+    (c as String).length()
+    return <!DEBUG_INFO_SMARTCAST!>c<!>.length() // Previous line should make as unnecessary here.
+}

compiler/testData/diagnostics/tests/smartCasts/variables/varAsUse.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun foo(): kotlin.Int
+internal fun get(): kotlin.Any

compiler/testData/diagnostics/tests/smartCasts/variables/varChangedInLoop.kt

@@ -0,0 +1,9 @@
+public fun foo() {
+    var i: Any = 1
+    if (i is Int) {
+        while (i != 10) {
+            <!UNUSED_CHANGED_VALUE!>i<!UNRESOLVED_REFERENCE!>++<!><!>      // Here smart cast should not be performed due to a successor
+            i = ""
+        }
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/varChangedInLoop.txt

@@ -0,0 +1,3 @@
+package
+
+public fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.kt

@@ -0,0 +1,8 @@
+public fun foo() {
+    var i: Any = 1
+    if (i is Int) {
+        while (i != 10) {
+            <!DEBUG_INFO_SMARTCAST!>i<!>++
+        }
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.txt

@@ -0,0 +1,3 @@
+package
+
+public fun foo(): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.kt

@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: Any): Int {
+    var p = pp
+    while(true) {
+        (p as String).length()
+        if (x()) break
+        p = 42
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = 42 makes it difficult to understand)
+    return p.<!UNRESOLVED_REFERENCE!>length<!>()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.txt

@@ -0,0 +1,4 @@
+package
+
+public fun foo(/*0*/ pp: kotlin.Any): kotlin.Int
+internal fun x(): kotlin.Boolean

compiler/testData/diagnostics/tests/smartCasts/variables/whileWithBreak.kt

@@ -0,0 +1,17 @@
+fun String.next(): String {
+    return "abc"
+}
+
+fun list(start: String) {
+    var e: Any? = start
+    if (e==null) return
+    while (e is String) {
+        // Smart cast due to the loop condition
+        if (<!DEBUG_INFO_SMARTCAST!>e<!>.length() == 0)
+            break
+        // We still have smart cast here despite of a break
+        e = <!DEBUG_INFO_SMARTCAST!>e<!>.next()
+    }
+    // e can never be null but we do not know it
+    e<!UNSAFE_CALL!>.<!>hashCode()
+}

compiler/testData/diagnostics/tests/smartCasts/variables/whileWithBreak.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun list(/*0*/ start: kotlin.String): kotlin.Unit
+internal fun kotlin.String.next(): kotlin.String