[Bug]: Getting `Symbol is 'null'`and fail whenever executes Semantic APIs in compiler extension in package 'ballerina:sql:1.12.0'

[dulajdilshan]

Description

The ballerina source code would not compile. error: compilation failed: The compiler extension in package 'ballerina:sql:1.12.0' failed to complete. Symbol is 'null'

error: compilation failed: The compiler extension in package 'ballerina:sql:1.12.0' failed to complete. Symbol is 'null'

Steps to Reproduce

Affected Version(s)

2201.8.4 and 2201.8.6. Probably version 8

OS, DB, other environment details and versions

No response

Related area

-> Compilation

Related issue(s) (optional)

No response

Suggested label(s) (optional)

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Suggested assignee(s) (optional)

No response

[dulajdilshan]

What happens in the Semantic API internally is we are trying to get the symbol from the in the definition() of BallerinaTypeReferenceTypeSymvol, it getts null in the symbol.

https://github.com/ballerina-platform/ballerina-lang/blob/254d5cd94649e179fabf0d8d254192785d7b17ce/compiler/ballerina-lang/src/main/java/io/ballerina/compiler/api/impl/symbols/BallerinaTypeReferenceTypeSymbol.java#L116

This is the place we get the exception originated https://github.com/ballerina-platform/ballerina-lang/blob/254d5cd94649e179fabf0d8d254192785d7b17ce/compiler/ballerina-lang/src/main/java/io/ballerina/compiler/api/impl/SymbolFactory.java#L151

Things to check first.

• Debug the SQL tool against the given Ballerina source code and check whether we are getting the correct semantic model.
• If it is correct, we need verify that we are creating the correct symbol in SymbolFactory.getBCompiledSymbol function.
• Check whether that why we are not getting the symbol in the scope.

[nipunayf]

The issue originated from version 2201.8.0 onwards, as it builds for version 2201.7.5. The primary reason for this issue is that the owner of the tSymbol produced by the getDeterminedType API is invalid. The owner of the tSymbol produced for decodedJwt in https://github.com/avishka95/digiops-finance/blob/d0ba0d88fe5bb20c9c54786db756b62b76326685/apps/expense-claims/backend/service.bal#L254 is the same as the owner of the tSymbol referred via jwt in https://github.com/avishka95/digiops-finance/blob/d0ba0d88fe5bb20c9c54786db756b62b76326685/apps/expense-claims/backend/request_interceptor.bal#L29.

Moreover, making the following changes to the code temporarily resolves the problem:

1. If we remove the type narrowing here and have a check expression here https://github.com/avishka95/digiops-finance/blob/d0ba0d88fe5bb20c9c54786db756b62b76326685/apps/expense-claims/backend/service.bal#L242-L249.
2. Remove the cloneReadonly and have the variable as it is. Apparently, the issue is only visible if we use the lang lib methods associated with it.

[nipunayf]

The problem can be narrowed down to the following source code.

import ballerina/sql;

sql:ConnectionPool connPool = {};

public type Rec record {
    int id;
    string name;
};


function fn() {
    readonly & Rec|int rec = 1;
    if rec is int {
        return;
    }
    _ = rec.entries();
}

The following observations can be recorded for the above code:

1. The sql module should be imported to run the syntax analysis task in the compiler plugin.
2. A record should be defined, and an immutable record with a union type should be created as a local variable.
3. After a type narrowing, access the respective variable using a library method.

[nipunayf]

Consider the following cases and the determined type for each variable reference (rec1, rec2, and rec3). Ideally, all these types should be consistent. However, as we've seen in the commit, the type narrower sets the effective type as the narrowed type for the case 1 (it sets the RecordType).

public type Rec record {
    int id;
    string name;
};

function fn() returns error? {
    // Case 1: with type narrowing
    readonly & Rec|int rec1 = 1;
    if rec1 is int {
        return;
    }
    _ = rec1.entries(); // RecordType 

    // Case 2: with check expression
    readonly & Rec rec2 = check returnRecOrError(); 
    _ = rec2.entries(); // IntersectionType

    // Case 3: with type cast
    readonly & Rec|int rec3 = 1;
    _ = (<readonly & Rec>rec3).entries(); // IntersectionType
}

function returnRecOrError() returns readonly & Rec|error => error("error");

[nipunayf]

Added to the 2201.8.7 milestone: https://github.com/ballerina-platform/ballerina-release/issues/2631

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