[FIR] Forbid complex boolean expressions

Disabling the language feature is supported,
otherwise there are too many tests that
would need to be updated to account for
K2's inability to do it.

The `ifConstVal.kt` test is deleted,
because now it must also be ignored in K2,
and since it is ignored for both the
frontends, and the ignored backends
include all the target backends, this test
is basically unused.

Note that now both the frontends report
`CONST_VAL_WITH_NON_CONST_INITIALIZER`.
for `condition`.

^KT-55196 Fixed

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

@@ -795,6 +795,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             runTest("compiler/testData/diagnostics/tests/noUnusedOnDelegationWithProvider.kt");
         }
 
+        @Test
+        @TestMetadata("nonConstNotCall.kt")
+        public void testNonConstNotCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/nonConstNotCall.kt");
+        }
+
         @Test
         @TestMetadata("Nullability.kt")
         public void testNullability() throws Exception {

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

@@ -795,6 +795,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             runTest("compiler/testData/diagnostics/tests/noUnusedOnDelegationWithProvider.kt");
         }
 
+        @Test
+        @TestMetadata("nonConstNotCall.kt")
+        public void testNonConstNotCall() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/nonConstNotCall.kt");
+        }
+
         @Test
         @TestMetadata("Nullability.kt")
         public void testNullability() throws Exception {

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirConstChecks.kt

@@ -8,7 +8,7 @@ package org.jetbrains.kotlin.fir.analysis.checkers
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
-import org.jetbrains.kotlin.fir.*
+import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirProperty
 import org.jetbrains.kotlin.fir.declarations.hasAnnotation
 import org.jetbrains.kotlin.fir.declarations.utils.isConst
@@ -16,6 +16,7 @@ import org.jetbrains.kotlin.fir.declarations.utils.isStatic
 import org.jetbrains.kotlin.fir.declarations.utils.modality
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.impl.FirNoReceiverExpression
+import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.references.FirErrorNamedReference
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.references.toResolvedCallableSymbol
@@ -24,6 +25,7 @@ import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.unwrapFakeOverrides
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.util.OperatorNameConventions
@@ -76,7 +78,7 @@ internal fun checkConstantArguments(
         }
         expression is FirStringConcatenationCall || expression is FirEqualityOperatorCall -> {
             for (exp in (expression as FirCall).arguments) {
-                if (exp is FirResolvedQualifier) {
+                if (exp is FirResolvedQualifier || expression.isForbiddenComplexConstant(session)) {
                     return ConstantArgumentKind.NOT_CONST
                 }
                 checkConstantArguments(exp, session)?.let { return it }
@@ -132,7 +134,7 @@ internal fun checkConstantArguments(
             if (calleeReference !is FirResolvedNamedReference) return ConstantArgumentKind.NOT_CONST
             val symbol = calleeReference.resolvedSymbol as? FirNamedFunctionSymbol ?: return ConstantArgumentKind.NOT_CONST
 
-            if (!symbol.canBeEvaluated() && !expression.isCompileTimeBuiltinCall()) {
+            if (!symbol.canBeEvaluated() && !expression.isCompileTimeBuiltinCall() || expression.isForbiddenComplexConstant(session)) {
                 return ConstantArgumentKind.NOT_CONST
             }
 
@@ -184,6 +186,30 @@ internal fun checkConstantArguments(
     return null
 }
 
+private fun FirExpression.isForbiddenComplexConstant(session: FirSession): Boolean {
+    val forbidComplexBooleanExpressions = session.languageVersionSettings.supportsFeature(
+        LanguageFeature.ProhibitSimplificationOfNonTrivialConstBooleanExpressions
+    )
+    return isComplexBooleanConstant && forbidComplexBooleanExpressions
+}
+
+private val FirExpression.isComplexBooleanConstant
+    get(): Boolean = when {
+        !typeRef.coneType.isBoolean -> false
+        this is FirConstExpression<*> -> false
+        usesVariableAsConstant -> false
+        else -> true
+    }
+
+/**
+ * See: org.jetbranis.kotlin.resolve.constants.CompileTimeConstant.Parameters.usesVariableAsConstant
+ */
+@Suppress("RecursivePropertyAccessor")
+private val FirExpression.usesVariableAsConstant: Boolean
+    get() = this is FirPropertyAccessExpression && toResolvedCallableSymbol()?.isConst == true
+            || this is FirQualifiedAccessExpression && explicitReceiver?.usesVariableAsConstant != false
+            || this is FirCall && this.arguments.any { it.usesVariableAsConstant }
+
 private val compileTimeFunctions = setOf(
     *OperatorNameConventions.BINARY_OPERATION_NAMES.toTypedArray(), *OperatorNameConventions.UNARY_OPERATION_NAMES.toTypedArray(),
     OperatorNameConventions.SHL, OperatorNameConventions.SHR, OperatorNameConventions.USHR,

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenTestGenerated.java

@@ -28904,12 +28904,6 @@ public class FirLightTreeBlackBoxCodegenTestGenerated extends AbstractFirLightTr
                 runTest("compiler/testData/codegen/box/involvesIrInterpreter/intrinsicConst/equals_after.kt");
             }
 
-            @Test
-            @TestMetadata("ifConstVal.kt")
-            public void testIfConstVal() throws Exception {
-                runTest("compiler/testData/codegen/box/involvesIrInterpreter/intrinsicConst/ifConstVal.kt");
-            }
-
             @Test
             @TestMetadata("kCallableName.kt")
             public void testKCallableName() throws Exception {

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirPsiBlackBoxCodegenTestGenerated.java

@@ -28904,12 +28904,6 @@ public class FirPsiBlackBoxCodegenTestGenerated extends AbstractFirPsiBlackBoxCo
                 runTest("compiler/testData/codegen/box/involvesIrInterpreter/intrinsicConst/equals_after.kt");
             }
 
-            @Test
-            @TestMetadata("ifConstVal.kt")
-            public void testIfConstVal() throws Exception {
-                runTest("compiler/testData/codegen/box/involvesIrInterpreter/intrinsicConst/ifConstVal.kt");
-            }
-
             @Test
             @TestMetadata("kCallableName.kt")
             public void testKCallableName() throws Exception {