Add fallback flag for legacy var smart casts after try #KT-21377 Fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt

@@ -112,6 +112,12 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
     )
     var newInference: Boolean by FreezableVar(false)
 
+    @Argument(
+            value = "-Xlegacy-smart-cast-after-try",
+            description = "Allow var smart casts despite assignment in try block"
+    )
+    var legacySmartCastAfterTry by FreezableVar(false)
+
     open fun configureAnalysisFlags(collector: MessageCollector): MutableMap<AnalysisFlag<*>, Any> {
         return HashMap<AnalysisFlag<*>, Any>().apply {
             put(AnalysisFlag.skipMetadataVersionCheck, skipMetadataVersionCheck)

compiler/cli/src/org/jetbrains/kotlin/cli/common/CLICompiler.java

@@ -208,6 +208,10 @@ public abstract class CLICompiler<A extends CommonCompilerArguments> extends CLI
             extraLanguageFeatures.put(LanguageFeature.NewInference, LanguageFeature.State.ENABLED);
         }
 
+        if (arguments.getLegacySmartCastAfterTry()) {
+            extraLanguageFeatures.put(LanguageFeature.SoundSmartCastsAfterTry, LanguageFeature.State.DISABLED);
+        }
+
         setupPlatformSpecificLanguageFeatureSettings(extraLanguageFeatures, arguments);
 
         CommonConfigurationKeysKt.setLanguageVersionSettings(configuration, new LanguageVersionSettingsImpl(

compiler/testData/cli/js/jsExtraHelp.out

@@ -7,6 +7,7 @@ where advanced options include:
   -Xcoroutines={enable|warn|error}
                              Enable coroutines or report warnings or errors on declarations and use sites of 'suspend' modifier
   -Xintellij-plugin-root=<path> Path to the kotlin-compiler.jar or directory where IntelliJ configuration files can be found
+  -Xlegacy-smart-cast-after-try Allow var smart casts despite assignment in try block
   -Xmulti-platform           Enable experimental language support for multi-platform projects
   -Xnew-inference            Enable new experimental generic type inference algorithm
   -Xno-check-actual          Do not check presence of 'actual' modifier in multi-platform projects

compiler/testData/cli/jvm/extraHelp.out

@@ -34,6 +34,7 @@ where advanced options include:
   -Xcoroutines={enable|warn|error}
                              Enable coroutines or report warnings or errors on declarations and use sites of 'suspend' modifier
   -Xintellij-plugin-root=<path> Path to the kotlin-compiler.jar or directory where IntelliJ configuration files can be found
+  -Xlegacy-smart-cast-after-try Allow var smart casts despite assignment in try block
   -Xmulti-platform           Enable experimental language support for multi-platform projects
   -Xnew-inference            Enable new experimental generic type inference algorithm
   -Xno-check-actual          Do not check presence of 'actual' modifier in multi-platform projects

compiler/testData/cli/jvm/legacySmartCastsAfterTry.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/legacySmartCastsAfterTry.kt
+-d
+$TEMP_DIR$
+-Xlegacy-smart-cast-after-try

compiler/testData/cli/jvm/legacySmartCastsAfterTry.kt

@@ -0,0 +1,9 @@
+fun foo() {
+    var some: String? = null
+    some = "alpha"
+    try {
+        some = "omega"
+    }
+    catch (e: Exception) {}
+    some.length
+}

compiler/testData/cli/jvm/legacySmartCastsAfterTry.out

@@ -0,0 +1,4 @@
+compiler/testData/cli/jvm/legacySmartCastsAfterTry.kt:2:25: warning: variable 'some' initializer is redundant
+    var some: String? = null
+                        ^
+OK

compiler/tests/org/jetbrains/kotlin/cli/CliTestGenerated.java

@@ -338,6 +338,12 @@ public class CliTestGenerated extends AbstractCliTest {
             doJvmTest(fileName);
         }
 
+        @TestMetadata("legacySmartCastsAfterTry.args")
+        public void testLegacySmartCastsAfterTry() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/cli/jvm/legacySmartCastsAfterTry.args");
+            doJvmTest(fileName);
+        }
+
         @TestMetadata("multipleTextRangesInDiagnosticsOrder.args")
         public void testMultipleTextRangesInDiagnosticsOrder() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/cli/jvm/multipleTextRangesInDiagnosticsOrder.args");