[Bug]: Bad type on operand stack error when readonly table is returned

[pcnfernando]

Description

type Customer record {|
    readonly int id;
    readonly string name;
    int noOfItems;
|};

isolated table<Customer> key(id) customerTable = table [];

public function main() {
    _ = getApiKeywords();
}

isolated function getApiKeywords() returns readonly & table<Customer> key(id) {
    lock {
        return customerTable.cloneReadOnly();
    }
}

Stacktrace:

[2023-05-09 22:29:46,516] SEVERE {b7a.log.crash} - Bad type on operand stack
Exception Details:
  Location:
    test.main(Lio/ballerina/runtime/internal/scheduling/Strand;)Ljava/lang/Object; @3404: putfield
  Reason:
    Type 'java/lang/Object' (current frame, stack[2]) is not assignable to 'io/ballerina/runtime/internal/values/TableValueImpl'

Steps to Reproduce

No response

Affected Version(s)

v2201.5.0

OS, DB, other environment details and versions

No response

Related area

-> Compilation

Related issue(s) (optional)

No response

Suggested label(s) (optional)

No response

Suggested assignee(s) (optional)

No response

[pcnfernando]

As a workaround,

type Customer record {|
    readonly int id;
    readonly string name;
    int noOfItems;
|};

isolated table<Customer> key(id) customerTable = table [];

public function main() {
    _ = getApiKeywords();
}

isolated function getApiKeywords() returns table<Customer> key(id) {
    lock {
        return customerTable.cloneReadOnly();
    }
}

[pcnfernando]

Originally observed in https://github.com/abeykoon/choreo-marketplace/blob/experiment-idel-store/modules/api/saasApiStore.bal#L177

[SasinduDilshara]

In the Desugar, the function body of the getApiKeywords() function is generated as follows.

Return: <table<(Customer & readonly)> key(id) & readonly> ballerina/lang.value:0.0.0:Cloneable $v$1 = <ballerina/lang.value:0.0.0:Cloneable> customerTable

In the Desugar, the function body of the main function is generated as follows.

BLangFunction: [PUBLIC] main ([]) (null) Body: {_ = <any> ; Return: ()}

[SasinduDilshara]

In the Desugar, the function body of the getApiKeywords() function is generated as follows.

Return: <table<(Customer & readonly)> key(id) & readonly> ballerina/lang.value:0.0.0:Cloneable $v$1 = <ballerina/lang.value:0.0.0:Cloneable> customerTable

In the Desugar, the function body of the main function is generated as follows.

BLangFunction: [PUBLIC] main ([]) (null) Body: {_ = <any> ; Return: ()}

Seems like the return value of the getApiKeywords() function is casted into <table<(Customer & readonly)> key(id) & readonly>, which is the expected behaviour.

[SasinduDilshara]

Had a discussion with @HindujaB and sees like the issue is having in the runtime side.
Seems like handling intersection type inside the generateFrameClassFieldUpdateByTypeTag in MethodGen is wrong.

[github-actions]

This issue is NOT closed with a proper Reason/ label. Make sure to add proper reason label before closing. Please add or leave a comment with the proper reason label now.

      - Reason/EngineeringMistake - The issue occurred due to a mistake made in the past.
      - Reason/Regression - The issue has introduced a regression.
      - Reason/MultipleComponentInteraction - Issue occured due to interactions in multiple components.
      - Reason/Complex - Issue occurred due to complex scenario.
      - Reason/Invalid - Issue is invalid.
      - Reason/Other - None of the above cases.