[FIR] Prevent replacing UNNECESSARY_SAFE_CALL with UNEXPECTED_SAFE_CALL

UNNECESSARY_SAFE_CALL is a warning,
UNEXPECTED_SAFE_CALL is an error, thus
it's a breaking change.

Also see KT-60695.

^KT-59860 Fixed


Merge-request: KT-MR-11210
Merged-by: Nikolay Lunyak <Nikolay.Lunyak@jetbrains.com>

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -1245,6 +1245,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
             runTest("compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.kt");
         }
 
+        @Test
+        @TestMetadata("unexpectedSafeCall.kt")
+        public void testUnexpectedSafeCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/unexpectedSafeCall.kt");
+        }
+
         @Test
         @TestMetadata("UnitByDefaultForFunctionTypes.kt")
         public void testUnitByDefaultForFunctionTypes() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -1245,6 +1245,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
             runTest("compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.kt");
         }
 
+        @Test
+        @TestMetadata("unexpectedSafeCall.kt")
+        public void testUnexpectedSafeCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/unexpectedSafeCall.kt");
+        }
+
         @Test
         @TestMetadata("UnitByDefaultForFunctionTypes.kt")
         public void testUnitByDefaultForFunctionTypes() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java

@@ -1245,6 +1245,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             runTest("compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.kt");
         }
 
+        @Test
+        @TestMetadata("unexpectedSafeCall.kt")
+        public void testUnexpectedSafeCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/unexpectedSafeCall.kt");
+        }
+
         @Test
         @TestMetadata("UnitByDefaultForFunctionTypes.kt")
         public void testUnitByDefaultForFunctionTypes() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java

@@ -1245,6 +1245,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             runTest("compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.kt");
         }
 
+        @Test
+        @TestMetadata("unexpectedSafeCall.kt")
+        public void testUnexpectedSafeCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/unexpectedSafeCall.kt");
+        }
+
         @Test
         @TestMetadata("UnitByDefaultForFunctionTypes.kt")
         public void testUnitByDefaultForFunctionTypes() throws Exception {

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirUnnecessarySafeCallChecker.kt

@@ -12,8 +12,13 @@ import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.expressions.FirSafeCallExpression
+import org.jetbrains.kotlin.fir.expressions.calleeReference
 import org.jetbrains.kotlin.fir.languageVersionSettings
+import org.jetbrains.kotlin.fir.references.resolved
+import org.jetbrains.kotlin.fir.references.toResolvedCallableSymbol
 import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
+import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
+import org.jetbrains.kotlin.fir.types.ConeErrorType
 import org.jetbrains.kotlin.fir.types.canBeNull
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.fir.types.isUnit
@@ -21,7 +26,7 @@ import org.jetbrains.kotlin.fir.types.isUnit
 object FirUnnecessarySafeCallChecker : FirSafeCallExpressionChecker() {
     override fun check(expression: FirSafeCallExpression, context: CheckerContext, reporter: DiagnosticReporter) {
         val receiverType = expression.receiver.typeRef.coneType.fullyExpandedType(context.session)
-        if (receiverType.isUnit || expression.receiver.source?.elementType == KtNodeTypes.SUPER_EXPRESSION) {
+        if (expression.receiver.source?.elementType == KtNodeTypes.SUPER_EXPRESSION) {
             reporter.reportOn(expression.source, FirErrors.UNEXPECTED_SAFE_CALL, context)
             return
         }

compiler/testData/diagnostics/tests/SafeCallOnFakePackage.fir.kt

@@ -10,7 +10,7 @@ val s: String = "test"
 
 // FILE: test.kt
 fun ff() {
-    val a = <!NO_COMPANION_OBJECT!>Test<!><!UNEXPECTED_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>FOO<!>
+    val a = <!NO_COMPANION_OBJECT!>Test<!><!UNNECESSARY_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>FOO<!>
-    val b = <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>foo<!><!UNEXPECTED_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>s<!>
+    val b = <!EXPRESSION_EXPECTED_PACKAGE_FOUND!>foo<!><!UNNECESSARY_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>s<!>
-    <!NO_COMPANION_OBJECT!>System<!><!UNEXPECTED_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>out<!>.println(a + b)
+    <!NO_COMPANION_OBJECT!>System<!><!UNNECESSARY_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>out<!>.println(a + b)
 }

compiler/testData/diagnostics/tests/controlFlowAnalysis/safeCallAfterVariableInitialization.fir.kt

@@ -2,6 +2,6 @@
 
 fun test() {
     val b: Int
-    run { b = 1 }<!UNEXPECTED_SAFE_CALL!>?.<!>let {}
+    run { b = 1 }<!UNNECESSARY_SAFE_CALL!>?.<!>let {}
     b.inc()
 }

compiler/testData/diagnostics/tests/unexpectedSafeCall.kt

@@ -0,0 +1,8 @@
+// FIR_IDENTICAL
+// DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// ISSUE: KT-59860
+
+fun test() {
+    val b: Int
+    run { b = 1 }<!UNNECESSARY_SAFE_CALL!>?.<!>let {} // K1: UNNECESSARY_SAFE_CALL, K2: UNEXPECTED_SAFE_CALL
+}

compiler/testData/diagnostics/testsWithStdLib/resolve/javaStaticMembers.fir.kt

@@ -6,7 +6,7 @@ public class Test {
 // FILE: test.kt
 fun ff() {
     val a = Test.FOO
-    val b = <!NO_COMPANION_OBJECT!>Test<!><!UNEXPECTED_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>FOO<!>
+    val b = <!NO_COMPANION_OBJECT!>Test<!><!UNNECESSARY_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>FOO<!>
     System.out.println(a + b)
-    <!NO_COMPANION_OBJECT!>System<!><!UNEXPECTED_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>out<!>.println(a + b)
+    <!NO_COMPANION_OBJECT!>System<!><!UNNECESSARY_SAFE_CALL!>?.<!><!UNRESOLVED_REFERENCE!>out<!>.println(a + b)
 }

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -1245,6 +1245,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             runTest("compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.kt");
         }
 
+        @Test
+        @TestMetadata("unexpectedSafeCall.kt")
+        public void testUnexpectedSafeCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/unexpectedSafeCall.kt");
+        }
+
         @Test
         @TestMetadata("UnitByDefaultForFunctionTypes.kt")
         public void testUnitByDefaultForFunctionTypes() throws Exception {