FIR checker: report VAL_REASSIGNMENT on value parameter

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

@@ -12,13 +12,16 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
 import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.declarations.FirPropertyAccessor
+import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.FirVariableAssignment
 import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.references.FirBackingFieldReference
+import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 
 object FirValReassignmentChecker : FirVariableAssignmentChecker() {
     override fun check(expression: FirVariableAssignment, context: CheckerContext, reporter: DiagnosticReporter) {
         checkValReassignmentViaBackingField(expression, context, reporter)
+        checkValReassignmentOnValueParameter(expression, context, reporter)
     }
 
     private fun checkValReassignmentViaBackingField(
@@ -40,4 +43,13 @@ object FirValReassignmentChecker : FirVariableAssignmentChecker() {
             }
         }
     }
+
+    private fun checkValReassignmentOnValueParameter(
+        expression: FirVariableAssignment,
+        context: CheckerContext,
+        reporter: DiagnosticReporter
+    ) {
+        val valueParameter = (expression.lValue as? FirResolvedNamedReference)?.resolvedSymbol?.fir as? FirValueParameter ?: return
+        reporter.reportOn(expression.lValue.source, FirErrors.VAL_REASSIGNMENT, valueParameter.symbol, context)
+    }
 }

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

@@ -59,7 +59,7 @@ fun canBe(i0: Int, j: Int) {
     var i = i0
     (label@ i) = 34
 
-    (label@ j) = 34 //repeat for j
+    (label@ <!VAL_REASSIGNMENT!>j<!>) = 34 //repeat for j
 
     val a = A()
     (l@ a.a) = 3894
@@ -69,7 +69,7 @@ fun canBe(i0: Int, j: Int) {
 }
 
 fun canBe2(j: Int) {
-    (label@ j) = 34
+    (label@ <!VAL_REASSIGNMENT!>j<!>) = 34
 }
 
 class A() {

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

@@ -54,7 +54,7 @@ fun t2() {
 class A() {}
 
 fun t4(a: A) {
-    a = A()
+    <!VAL_REASSIGNMENT!>a<!> = A()
 }
 
 // ------------------------------------------------
@@ -188,7 +188,7 @@ class AnonymousInitializers(var a: String, val b: String) {
 }
 
 fun reassignFunParams(a: Int) {
-    a = 1
+    <!VAL_REASSIGNMENT!>a<!> = 1
 }
 
 open class Open(a: Int, w: Int) {}

compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInUnaryExpr.fir.kt

@@ -5,7 +5,7 @@ fun testPrefix() {
 
 fun testPostfixWithCall(n: Nothing) {
     operator fun Nothing.inc(): Nothing = this
-    n++
+    <!VAL_REASSIGNMENT!>n<!>++
 }
 
 fun testPostfixSpecial() {

compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClass.fir.kt

@@ -1,7 +0,0 @@
-@Suppress("warnings")
-class C {
-    fun foo(p: String??) {
-        // Make sure errors are not suppressed:
-        p = ""
-    }
-}

compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClass.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 @Suppress("warnings")
 class C {
     fun foo(p: String??) {

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/13.fir.kt

@@ -5,7 +5,7 @@
 // TESTCASE NUMBER: 1
 fun case_1(x: Class?) {
     x!!
-    <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>[if (true) {x=null;0} else 0] += <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>[0]
+    <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>[if (true) {<!VAL_REASSIGNMENT!>x<!>=null;0} else 0] += <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>[0]
     <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>
     <!DEBUG_INFO_EXPRESSION_TYPE("Class? & Class")!>x<!>[0].inv()
 }