FIR LL API: resolve PSI elements to more specific FIR element

Compound access and implicit delegated constructor are mapped to FIR
elements that are way too broad.

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/components/KtFirExpressionTypeProvider.kt

@@ -54,6 +54,13 @@ internal class KtFirExpressionTypeProvider(
                     fir.typeRef.coneType.asKtType()
                 }
             }
+            is FirVariableAssignment -> {
+                if (expression is KtUnaryExpression && expression.operationToken in KtTokens.INCREMENT_AND_DECREMENT) {
+                    fir.rValue.typeRef.coneType.asKtType()
+                } else {
+                    analysisSession.builtinTypes.UNIT
+                }
+            }
             is FirExpression -> fir.typeRef.coneType.asKtType()
             is FirNamedReference -> fir.getReferencedElementType(firResolveState).asKtType()
             is FirStatement -> with(analysisSession) { builtinTypes.UNIT }

analysis/analysis-api-fir/tests/org/jetbrains/kotlin/analysis/api/fir/components/expressionTypeProvider/FirHLExpressionTypeTestGenerated.java

@@ -120,6 +120,24 @@ public class FirHLExpressionTypeTestGenerated extends AbstractFirHLExpressionTyp
         runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/nonExpression.kt");
     }
 
+    @Test
+    @TestMetadata("plusAssign.kt")
+    public void testPlusAssign() throws Exception {
+        runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/plusAssign.kt");
+    }
+
+    @Test
+    @TestMetadata("postfixDec.kt")
+    public void testPostfixDec() throws Exception {
+        runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/postfixDec.kt");
+    }
+
+    @Test
+    @TestMetadata("prefixInc.kt")
+    public void testPrefixInc() throws Exception {
+        runTest("analysis/analysis-api/testData/components/expressionTypeProvider/expressionType/prefixInc.kt");
+    }
+
     @Test
     @TestMetadata("property.kt")
     public void testProperty() throws Exception {