Clear var nullability in loops more accurately #KT-14977 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DelegatingDataFlowInfo.kt

@@ -146,7 +146,7 @@ internal class DelegatingDataFlowInfo private constructor(
      */
     override fun clearValueInfo(value: DataFlowValue, languageVersionSettings: LanguageVersionSettings): DataFlowInfo {
         val builder = Maps.newHashMap<DataFlowValue, Nullability>()
-        putNullability(builder, value, Nullability.UNKNOWN, languageVersionSettings)
+        putNullability(builder, value, value.immanentNullability, languageVersionSettings)
         return create(this, ImmutableMap.copyOf(builder), EMPTY_TYPE_INFO, value)
     }
 

compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.kt

@@ -0,0 +1,15 @@
+fun readLine() = "x"
+
+fun foo() {
+    var line = ""
+
+    while (<!SENSELESS_COMPARISON!>line != null<!>) {
+        line = readLine()
+
+        if (<!SENSELESS_COMPARISON!>line != null<!>) {
+            bar()
+        }
+    }
+}
+
+fun bar() {}

compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.txt

@@ -0,0 +1,5 @@
+package
+
+public fun bar(): kotlin.Unit
+public fun foo(): kotlin.Unit
+public fun readLine(): kotlin.String

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -19183,6 +19183,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/senselessComparison"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
             }
 
+            @TestMetadata("noExplicitType.kt")
+            public void testNoExplicitType() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("parenthesized.kt")
             public void testParenthesized() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/senselessComparison/parenthesized.kt");