Implementation and tests for KT-5840 and newly created KT-7204. Now a safe call provides not-null receiver state *inside* argument list. It works also for ?. chains. #KT-5840 Fixed.

On the other hand, argument states do not propagate to successor statements for a safe call. #KT-7204 Fixed. A few additional comments.

compiler/testData/diagnostics/tests/smartCasts/safecalls/anotherVal.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?, y: Int?): Int {
+    x?.get(y!! - 1) 
+    // y!! above should not provide smart cast here
+    val yy: Int = <!TYPE_MISMATCH!>y<!>
+    return  yy + (x?.size() ?: 0)
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/anotherVal.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?, /*1*/ y: kotlin.Int?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // After KT-5840 fix !! assertion should become unnecessary here
+    x?.get(x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>.size() - 1) 
+    // x?. or x!! above should not provide smart cast here
+    return x<!UNSAFE_CALL!>.<!>size()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainAndUse.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list, despite of a chain
+    x?.subList(0, 1)?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size())
+    // But not here!
+    return x!!.size()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainAndUse.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainInChain.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?, y: List<Int>?) {
+    // x and y should be non-null in arguments list, despite of a chains
+    x?.subList(y?.subList(1, 2)?.get(<!DEBUG_INFO_SMARTCAST!>y<!>.size()) ?: 0, 
+               y?.get(0) ?: 1) // But safe call is NECESSARY here for y
+     ?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size()) 
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainInChain.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?, /*1*/ y: kotlin.List<kotlin.Int>?): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list, despite of a chain
+    x?.subList(0, 1)<!UNSAFE_CALL!>.<!>get(<!DEBUG_INFO_SMARTCAST!>x<!>.size())
+    // But not here!
+    return x!!.size()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/doubleCall.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list, including inner call
+    x?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size() - 1).length()) 
+    // but not also here!
+    return x<!UNSAFE_CALL!>.<!>size()               
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/doubleCall.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/extension.kt

@@ -0,0 +1,6 @@
+fun String.foo(arg: Int) = this[arg]
+
+fun calc(x: String?) {
+    // x should be non-null in arguments list
+    x?.foo(<!DEBUG_INFO_SMARTCAST!>x<!>.length() - 1) 
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/extension.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.String?): kotlin.Unit
+internal fun kotlin.String.foo(/*0*/ arg: kotlin.Int): kotlin.Char

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseArgument.kt

@@ -0,0 +1,7 @@
+fun foo(y: Int) = y
+
+fun calc(x: List<String>?): Int {
+    foo(x!!.size())
+    // Here we should have smart cast because of x!!, despite of KT-7204 fixed
+    return <!DEBUG_INFO_SMARTCAST!>x<!>.size()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseArgument.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int
+internal fun foo(/*0*/ y: kotlin.Int): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseChain.kt

@@ -0,0 +1,4 @@
+fun calc(x: List<String>?, y: Int?) {
+    // Smart cast should work here despite of KT-7204 fixed
+    x?.subList(0, y!!)?.get(<!DEBUG_INFO_SMARTCAST!>y<!>) 
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseChain.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?, /*1*/ y: kotlin.Int?): kotlin.Unit

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseExtension.kt

@@ -0,0 +1,7 @@
+fun String.foo(y: Int) = y
+
+fun calc(x: List<String>?): Int {
+    "abc".foo(x!!.size())
+    // Here we should have smart cast because of x!!, despite of KT-7204 fixed
+    return <!DEBUG_INFO_SMARTCAST!>x<!>.size()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseExtension.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int
+internal fun kotlin.String.foo(/*0*/ y: kotlin.Int): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseSecondArgument.kt

@@ -0,0 +1,5 @@
+fun calc(x: List<String>?, y: Int?): Int {
+    x?.subList(y!! - 1, <!DEBUG_INFO_SMARTCAST!>y<!>)
+    // y!! above should not provide smart cast here
+    return <!TYPE_MISMATCH!>y<!>
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/falseSecondArgument.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?, /*1*/ y: kotlin.Int?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/innerReceiver.kt

@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?, y: String?): Int {
+    // Smart cast because of y!! in receiver
+    x?.subSequence(y!!.subSequence(0, 1).length(), <!DEBUG_INFO_SMARTCAST!>y<!>.length())
+    // No smart cast possible
+    return y<!UNSAFE_CALL!>.<!>length()
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/innerReceiver.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.String?, /*1*/ y: kotlin.String?): kotlin.Int
+internal fun foo(/*0*/ x: kotlin.String): kotlin.String?

compiler/testData/diagnostics/tests/smartCasts/safecalls/insideCall.kt

@@ -0,0 +1,8 @@
+fun foo(y: Int): Int {
+    return y + 1
+}
+
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    return foo(x?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size() - 1)!!.length())
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/insideCall.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int
+internal fun foo(/*0*/ y: kotlin.Int): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/longChain.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?) {
+    // x should be non-null in arguments list, despite of a chain
+    x?.subList(0, <!DEBUG_INFO_SMARTCAST!>x<!>.size())?.
+       subList(0, <!DEBUG_INFO_SMARTCAST!>x<!>.size())?.
+       get(<!DEBUG_INFO_SMARTCAST!>x<!>.size()) 
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/longChain.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Unit

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

@@ -0,0 +1,6 @@
+data class MyClass(val x: String?)
+
+fun foo(y: MyClass): Int {
+    val z = y.x?.subSequence(0, <!DEBUG_INFO_SMARTCAST!>y.x<!>.length())
+    return z?.length() ?: -1
+}

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

@@ -0,0 +1,13 @@
+package
+
+internal fun foo(/*0*/ y: MyClass): kotlin.Int
+
+kotlin.data() internal final class MyClass {
+    public constructor MyClass(/*0*/ x: kotlin.String?)
+    internal final val x: kotlin.String?
+    internal final /*synthesized*/ fun component1(): kotlin.String?
+    public final /*synthesized*/ fun copy(/*0*/ x: kotlin.String? = ...): MyClass
+    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/safecalls/receiver.kt

@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(0, <!DEBUG_INFO_SMARTCAST!>x<!>.length())
+    // Smart cast because of x!! in receiver
+    return <!DEBUG_INFO_SMARTCAST!>x<!>.length()    
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/receiver.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.String?): kotlin.Int
+internal fun foo(/*0*/ x: kotlin.String): kotlin.String?

compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChain.kt

@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(0, <!DEBUG_INFO_SMARTCAST!>x<!>.length())?.length()
+    // Smart cast because of x!! in receiver
+    return <!DEBUG_INFO_SMARTCAST!>x<!>.length()    
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChain.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.String?): kotlin.Int
+internal fun foo(/*0*/ x: kotlin.String): kotlin.String?

compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChainFalse.kt

@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?, y: Int?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(y!!, <!DEBUG_INFO_SMARTCAST!>x<!>.length())?.length()
+    // No smart cast possible
+    return <!TYPE_MISMATCH!>y<!>    
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChainFalse.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.String?, /*1*/ y: kotlin.Int?): kotlin.Int
+internal fun foo(/*0*/ x: kotlin.String): kotlin.String?

compiler/testData/diagnostics/tests/smartCasts/safecalls/simple.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    x?.get(<!DEBUG_INFO_SMARTCAST!>x<!>.size() - 1) 
+    // but not also here!
+    return x<!UNSAFE_CALL!>.<!>size()               
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/simple.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int

compiler/testData/diagnostics/tests/smartCasts/safecalls/twoArgs.kt

@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    x?.subList(<!DEBUG_INFO_SMARTCAST!>x<!>.size() - 1, <!DEBUG_INFO_SMARTCAST!>x<!>.size()) 
+    // but not also here!
+    return x<!UNSAFE_CALL!>.<!>size()               
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/twoArgs.txt

@@ -0,0 +1,3 @@
+package
+
+internal fun calc(/*0*/ x: kotlin.List<kotlin.String>?): kotlin.Int