[FIR] Typing for try-catch

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirBodyResolveTransformer.kt

@@ -484,6 +484,22 @@ open class FirBodyResolveTransformer(val session: FirSession, val implicitTypeOn
         return functionCall
     }
 
+    override fun transformTryExpression(tryExpression: FirTryExpression, data: Any?): CompositeTransformResult<FirStatement> {
+        val tryExpression = tryExpression.transformChildren(this, data) as FirTryExpression
+        if (tryExpression.resultType !is FirResolvedTypeRef) {
+            val type = commonSuperType((listOf(tryExpression.tryBlock) + tryExpression.catches.map { it.block }).mapNotNull {
+                val expression = it.statements.lastOrNull() as? FirExpression
+                if (expression != null) {
+                    (expression.resultType as? FirResolvedTypeRef) ?: FirErrorTypeRefImpl(session, null, "No type for when branch result")
+                } else {
+                    FirImplicitUnitTypeRef(session, null)
+                }
+            })
+            if (type != null) tryExpression.resultType = type
+        }
+        return tryExpression.compose()
+    }
+
     override fun transformFunctionCall(functionCall: FirFunctionCall, data: Any?): CompositeTransformResult<FirStatement> {
         if (functionCall.calleeReference !is FirSimpleNamedReference) return functionCall.compose()
         val expectedTypeRef = data as FirTypeRef?

compiler/testData/ir/irText/declarations/catchParameterInTopLevelProperty.fir.txt

@@ -1,15 +1,14 @@
 FILE fqName:<root> fileName:/catchParameterInTopLevelProperty.kt
   PROPERTY name:test visibility:public modality:FINAL [val] 
-    FIELD PROPERTY_BACKING_FIELD name:test type:IrErrorType visibility:public [final,static] 
+    FIELD PROPERTY_BACKING_FIELD name:test type:kotlin.Unit visibility:public [final,static]
       EXPRESSION_BODY
-        TRY type=IrErrorType
+        TRY type=kotlin.Unit
           try: BLOCK type=kotlin.Unit origin=null
           CATCH parameter=val e: kotlin.Throwable [val] declared in <root>.test
             VAR name:e type:kotlin.Throwable [val] 
             BLOCK type=kotlin.Unit origin=null
-    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test> visibility:public modality:FINAL <> () returnType:IrErrorType 
+    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-test> visibility:public modality:FINAL <> () returnType:kotlin.Unit
       correspondingProperty: PROPERTY name:test visibility:public modality:FINAL [val] 
       BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public final fun <get-test> (): IrErrorType declared in <root>'
-          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test type:IrErrorType visibility:public [final,static] ' type=IrErrorType origin=null
-
+        RETURN type=kotlin.Nothing from='public final fun <get-test> (): kotlin.Unit declared in <root>'
+          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:test type:kotlin.Unit visibility:public [final,static] ' type=kotlin.Unit origin=null

compiler/testData/ir/irText/expressions/catchParameterAccess.fir.txt

@@ -1,9 +1,9 @@
 FILE fqName:<root> fileName:/catchParameterAccess.kt
-  FUN name:test visibility:public modality:FINAL <> (f:kotlin.Function0<kotlin.Unit>) returnType:IrErrorType 
+  FUN name:test visibility:public modality:FINAL <> (f:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Nothing?
     VALUE_PARAMETER name:f index:0 type:kotlin.Function0<kotlin.Unit> 
     BLOCK_BODY
-      RETURN type=kotlin.Nothing from='public final fun test (f: kotlin.Function0<kotlin.Unit>): IrErrorType declared in <root>'
-        TRY type=IrErrorType
+      RETURN type=kotlin.Nothing from='public final fun test (f: kotlin.Function0<kotlin.Unit>): kotlin.Nothing? declared in <root>'
+        TRY type=kotlin.Nothing?
           try: ERROR_CALL 'Unresolved reference: <Unresolved name: f>#' type=IrErrorType
           CATCH parameter=val e: java.lang.Exception [val] declared in <root>.test
             VAR name:e type:java.lang.Exception [val] 

compiler/testData/ir/irText/expressions/tryCatch.fir.txt

@@ -1,7 +1,7 @@
 FILE fqName:<root> fileName:/tryCatch.kt
   FUN name:test1 visibility:public modality:FINAL <> () returnType:kotlin.Unit 
     BLOCK_BODY
-      TRY type=IrErrorType
+      TRY type=kotlin.Unit
         try: CALL 'public final fun println (): kotlin.Unit [inline] declared in kotlin.io' type=kotlin.Unit origin=null
         CATCH parameter=val e: kotlin.Throwable [val] declared in <root>.test1
           VAR name:e type:kotlin.Throwable [val] 
@@ -10,7 +10,7 @@ FILE fqName:<root> fileName:/tryCatch.kt
   FUN name:test2 visibility:public modality:FINAL <> () returnType:kotlin.Int 
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='public final fun test2 (): kotlin.Int declared in <root>'
-        TRY type=IrErrorType
+        TRY type=kotlin.Int
           try: BLOCK type=kotlin.Int origin=null
             CALL 'public final fun println (): kotlin.Unit [inline] declared in kotlin.io' type=kotlin.Unit origin=null
             CONST Int type=kotlin.Int value=42

compiler/testData/ir/irText/expressions/tryCatchWithImplicitCast.fir.txt

@@ -9,7 +9,7 @@ FILE fqName:<root> fileName:/tryCatchWithImplicitCast.kt
           then: RETURN type=kotlin.Nothing from='public final fun testImplicitCast (a: kotlin.Any): kotlin.Unit declared in <root>'
             GET_OBJECT 'CLASS IR_EXTERNAL_DECLARATION_STUB OBJECT name:Unit modality:FINAL visibility:public superTypes:[kotlin.Any]' type=kotlin.Unit
       VAR name:t type:kotlin.String [val] 
-        TRY type=IrErrorType
+        TRY type=kotlin.String
           try: GET_VAR 'a: kotlin.Any declared in <root>.testImplicitCast' type=kotlin.Any origin=null
           CATCH parameter=val e: kotlin.Throwable [val] declared in <root>.testImplicitCast
             VAR name:e type:kotlin.Throwable [val]