KT-5182 Data flow info is lost for 'when' branches

#KT-5158 Fixed
  #KT-4332 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java

@@ -106,7 +106,7 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
                 dataFlowInfoForEntryBody = elseDataFlowInfo;
             }
             else {
-                dataFlowInfoForEntryBody = infosForCondition.thenInfo;
+                dataFlowInfoForEntryBody = infosForCondition.thenInfo.and(elseDataFlowInfo);
                 elseDataFlowInfo = elseDataFlowInfo.and(infosForCondition.elseInfo);
             }
 

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryAs.kt

@@ -4,7 +4,7 @@ fun foo(x: Number, y: Int) {
         y -> {}
         else -> {}
     }
-    <!TYPE_MISMATCH!>x<!> : Int
+    <!DEBUG_INFO_AUTOCAST!>x<!> : Int
 }
 
 fun bar(x: Number) {

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryIs.kt

@@ -0,0 +1,24 @@
+fun foo(x: Number, y: Int) {
+    when (x) {
+        is Int -> <!DEBUG_INFO_AUTOCAST!>x<!> : Int
+        y -> {}
+        else -> {}
+    }
+    <!TYPE_MISMATCH!>x<!> : Int
+}
+
+fun bar(x: Number) {
+    when (x) {
+        is Int -> <!DEBUG_INFO_AUTOCAST!>x<!> : Int
+        else -> {}
+    }
+    <!TYPE_MISMATCH!>x<!> : Int
+}
+
+fun whenWithoutSubject(x: Number) {
+    when {
+        (x is Int) -> <!DEBUG_INFO_AUTOCAST!>x<!> : Int
+        else -> {}
+    }
+    <!TYPE_MISMATCH!>x<!> : Int
+}

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt4332WhenBranches.kt

@@ -0,0 +1,9 @@
+//KT-4332 when/autocast underperforms
+
+fun testWhen(t: String?, x: String?): Int {
+    return when {
+        t == null -> 0
+        x == null -> <!DEBUG_INFO_AUTOCAST!>t<!>.length // Wrong error report here. t can be inferred as not-null. (And it actually does if you replace when with if/else if)
+        else -> (<!DEBUG_INFO_AUTOCAST!>t<!> + x).length
+    }
+}

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5182WhenBranches.kt

@@ -0,0 +1,13 @@
+//KT-5182 Data flow info is lost for 'when' branches
+
+open class A
+
+class B: A() {
+    fun foo() = 1
+}
+
+fun foo(a: A) = when {
+    a !is B -> 2
+    true -> <!DEBUG_INFO_AUTOCAST!>a<!>.foo() //'foo' is unresolved, smart cast doesn't work
+    else -> <!DEBUG_INFO_AUTOCAST!>a<!>.foo()
+}

compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt2146.kt

@@ -32,8 +32,9 @@ fun f4(s: Int?): Int {
 
 fun f5(s: Int?): Int {
     return when (s) {
-        s!! -> <!DEBUG_INFO_AUTOCAST!>s<!>
         s -> <!TYPE_MISMATCH!>s<!>
+        s!! -> <!DEBUG_INFO_AUTOCAST!>s<!>
+        s -> <!DEBUG_INFO_AUTOCAST!>s<!>
         else -> 0
     }
 }

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -2014,6 +2014,16 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IsExpression.kt");
             }
             
+            @TestMetadata("kt4332WhenBranches.kt")
+            public void testKt4332WhenBranches() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt4332WhenBranches.kt");
+            }
+            
+            @TestMetadata("kt5182WhenBranches.kt")
+            public void testKt5182WhenBranches() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5182WhenBranches.kt");
+            }
+            
             @TestMetadata("ManyIfs.kt")
             public void testManyIfs() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ManyIfs.kt");
@@ -2074,9 +2084,14 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/When.kt");
             }
             
-            @TestMetadata("WhenEntry.kt")
-            public void testWhenEntry() throws Exception {
-                doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntry.kt");
+            @TestMetadata("WhenEntryAs.kt")
+            public void testWhenEntryAs() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryAs.kt");
+            }
+            
+            @TestMetadata("WhenEntryIs.kt")
+            public void testWhenEntryIs() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryIs.kt");
             }
             
             @TestMetadata("WhenIn.kt")