Fix compiler crash with nested queries in select as a field

[poorna2152]

Purpose

Describe the problems, issues, or needs driving this feature/fix and include links to related issues.

Fixes #43336

Approach

The identifiers map in the QueryDesugar stores a set of identifiers and their symbols found in the lambda function created for clauses inside the query. When an identifier in a select clause is first used in a nested query or within a lambda function in a query, the symbol of that identifier is marked as a closure symbol. For consequent usages of this identifier in the select clause this symbol that has been marked as a closure should be used (i.e. for other fields in the select clause).

record {|string name; string[] courses;|}[] studentCourses = from Student student in students
        select {
            courses: from Grade grade in student.grades
                select grade.course,
            name: student.name
        };

Consider the above code. The student identifier inside the select clause is marked as a closure variable first because it is used within a nested query as in the first field. The second field also uses this student identifier and the variable of this second usage should also refer to the Symbol that is marked as a closure because of that nested field.

The current implementation restricts to using symbols of the identifiers from this identifiers map when either on in a nestedQuery or within an arrow function. This fix removes that check usage.

Samples

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Remarks

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Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.50%. Comparing base (c61fc38) to head (e3b2594).
Report is 115 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #43355      +/-   ##
============================================
- Coverage     77.50%   77.50%   -0.01%     
+ Complexity    58596    58593       -3     
============================================
  Files          3438     3438              
  Lines        219259   219259              
  Branches      28924    28924              
============================================
- Hits         169938   169926      -12     
- Misses        39902    39914      +12     
  Partials       9419     9419              

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[heshanpadmasiri]

LGTM