Fix unsound smartcast from loop condition on assigned vars

^KT-22379 Fixed

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/ControlStructureTypingVisitor.java

@@ -286,9 +286,16 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
             dataFlowInfo = dataFlowInfo.and(loopVisitor.clearDataFlowInfoForAssignedLocalVariables(bodyTypeInfo.getJumpFlowInfo(),
                                                                                                    components.languageVersionSettings));
         }
+
+        DataFlowInfo conservativeInfoAfterLoop =
+                components.languageVersionSettings.supportsFeature(LanguageFeature.SoundSmartcastFromLoopConditionForLoopAssignedVariables)
+                ? loopVisitor.clearDataFlowInfoForAssignedLocalVariables(dataFlowInfo, components.languageVersionSettings)
+                : dataFlowInfo;
+
+
         return components.dataFlowAnalyzer
                 .checkType(bodyTypeInfo.replaceType(components.builtIns.getUnitType()), expression, contextWithExpectedType)
-                .replaceDataFlowInfo(dataFlowInfo);
+                .replaceDataFlowInfo(conservativeInfoAfterLoop);
     }
 
     private boolean containsJumpOutOfLoop(@NotNull KtExpression expression, ExpressionTypingContext context) {
@@ -459,9 +466,14 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
             bodyTypeInfo = loopRangeInfo;
         }
 
+        DataFlowInfo conservativeInfoAfterLoop =
+                components.languageVersionSettings.supportsFeature(LanguageFeature.SoundSmartcastFromLoopConditionForLoopAssignedVariables)
+                ? loopVisitor.clearDataFlowInfoForAssignedLocalVariables(loopRangeInfo.getDataFlowInfo(), components.languageVersionSettings)
+                : loopRangeInfo.getDataFlowInfo();
+
         return components.dataFlowAnalyzer
                 .checkType(bodyTypeInfo.replaceType(components.builtIns.getUnitType()), expression, contextWithExpectedType)
-                .replaceDataFlowInfo(loopRangeInfo.getDataFlowInfo());
+                .replaceDataFlowInfo(conservativeInfoAfterLoop);
     }
 
     private VariableDescriptor createLoopParameterDescriptor(

compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.kt

@@ -0,0 +1,21 @@
+// !LANGUAGE: +SoundSmartcastFromLoopConditionForLoopAssignedVariables
+
+fun foo() {
+    var x: String? = "123"
+    while (x!!.length < 42) {
+        x = null
+        break
+
+    }
+    x<!UNSAFE_CALL!>.<!>length // 'x' is unsoundly smartcasted here
+}
+
+fun bar() {
+    var x: List<Int>? = ArrayList<Int>(1)
+    for (i in x!!) {
+        x = null
+        break
+
+    }
+    x<!UNSAFE_CALL!>.<!>size // 'x' is unsoundly smartcasted here
+}

compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.txt

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

compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.kt

@@ -0,0 +1,21 @@
+// !LANGUAGE: -SoundSmartcastFromLoopConditionForLoopAssignedVariables
+
+fun foo() {
+    var x: String? = "123"
+    while (x!!.length < 42) {
+        x = null
+        break
+
+    }
+    <!DEBUG_INFO_SMARTCAST!>x<!>.length // 'x' is unsoundly smartcasted here
+}
+
+fun bar() {
+    var x: List<Int>? = ArrayList<Int>(1)
+    for (i in x!!) {
+        x = null
+        break
+
+    }
+    <!DEBUG_INFO_SMARTCAST!>x<!>.size // 'x' is unsoundly smartcasted here
+}

compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.txt

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

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

@@ -19822,6 +19822,16 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 public void testWhileTrueWithBreakInIfCondition() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/loops/WhileTrueWithBreakInIfCondition.kt");
                 }
+
+                @TestMetadata("whileWithAssertInConditionAndBreakAfter.kt")
+                public void testWhileWithAssertInConditionAndBreakAfter() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.kt");
+                }
+
+                @TestMetadata("whileWithAssertInConditionAndBreakBefore.kt")
+                public void testWhileWithAssertInConditionAndBreakBefore() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.kt");
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/objectLiterals")

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -19822,6 +19822,16 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 public void testWhileTrueWithBreakInIfCondition() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/loops/WhileTrueWithBreakInIfCondition.kt");
                 }
+
+                @TestMetadata("whileWithAssertInConditionAndBreakAfter.kt")
+                public void testWhileWithAssertInConditionAndBreakAfter() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.kt");
+                }
+
+                @TestMetadata("whileWithAssertInConditionAndBreakBefore.kt")
+                public void testWhileWithAssertInConditionAndBreakBefore() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.kt");
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/objectLiterals")

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -85,6 +85,7 @@ enum class LanguageFeature(
     NormalizeConstructorCalls(KOTLIN_1_3),
     StrictJavaNullabilityAssertions(KOTLIN_1_3, kind = BUG_FIX),
     SoundSmartcastForEnumEntries(KOTLIN_1_3, kind = BUG_FIX),
+    SoundSmartcastFromLoopConditionForLoopAssignedVariables(KOTLIN_1_3, kind = BUG_FIX),
 
     RestrictReturnStatementTarget(KOTLIN_1_4, kind = BUG_FIX),
     ProperIeee754Comparisons(sinceVersion = null, defaultState = State.DISABLED, kind = BUG_FIX),