[Bug]: When inferring type for query-exp, collections of types other than query construct types should throw an error

[pcnfernando]

Description

From the spec https://ballerina.io/spec/lang/master/#section_6.35:

If there is no contextually expected type, then the basic type of the value constructed is the basic type of expression following in; it is a compile-time error if the static type of this expression is not a subtype of one of the basic types that a query expression can construct.

import ballerina/io;
public function main() {
    xml x = xml ``;
    var res = from xml i in x // we should get an error here incompatible types: 'xml' cannot be constrained with 'int'
    select 1;

    io:println(res is int[]); //error incompatible types: 'xml<int>' will not be matched to 'int[]'
}

public function main() {
    var res = from string i in "x"
    select 1; // atm, no errors. should be an error

    string x = res;
}

Steps to Reproduce

No response

Affected Version(s)

2201.2.0

OS, DB, other environment details and versions

No response

Labels

CompilerFE

Related issue(s) (optional)

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Suggested label(s) (optional)

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Suggested assignee(s) (optional)

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[SasinduDilshara]

public function main() {
    var res = from string i in "xyz"
    select 1;
}

But isn't it better if we return int[] type from the above query.
It will improve the user experience.

[pcnfernando]

If the user actually needs to create an int[], instead of inferring the type; the user can write the code with a contextually expected type.

public function main() {
    int[] res = from string i in "XYZ" //this works
    select 1;
}

[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.

[SasinduDilshara]

This issue reopened due to #40497

[pcnfernando]

As per https://ballerina.io/spec/lang/master/#section_6.35.10,
A query-select-expr that constructs a mapping or stream must specify a query-construct-type of map or stream respectively.

[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.