feat: add gang (struct) keyword

[leo-aa88]

Description

Adds struct support to the Brainrot language via the gang keyword.

Syntax

gang Point {
    rizz x;
    rizz y;
    chad magnitude;
};

skibidi main {
    gang Point p;
    p.x = 3;
    p.y = 4;
    p.magnitude = 5.0;
    yapping("Point: %d %d %.1f", p.x, p.y, p.magnitude);

    gang Point q = {10, 20, 0.0};
    yapping("Q: %d %d %.1f", q.x, q.y, q.magnitude);
}

What's included

• gang keyword and DOT token in the lexer
• struct_def, struct_field_list, struct_field grammar rules in the parser
• Struct registry (register_struct_def, get_struct_def, find_struct_field) backed by a hashmap
• Sequential memory layout via compute_struct_layout with per-field byte offsets
• VAR_STRUCT variable type and blob allocation via calloc at declaration time
• Member read/write through evaluate_struct_member_address used by all evaluate_expression_* functions
• Runtime field type resolution in execute_assignment for correct write dispatch
• NODE_STRUCT_ACCESS support in is_expression and ast_expr_to_stdrot_value for yapping integration
• Uninitialised (gang Point p) and initialised (gang Point q = {10, 20, 0.0}) declaration forms
• Struct blob and struct_name freed in hm_free; StructDef ownership tracked via intrusive next_def list and freed in free_struct_registry
• Early return in interpreter_visit_declaration for VAR_STRUCT nodes to prevent double-initialisation

Known limitations

• Nested struct access (p.inner.x) not yet supported
• Struct function parameters and return values not yet supported

Implements #100.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Performance improvement
• Refactor

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have documented my changes in the code or documentation
• I have added tests that prove my changes work (if applicable)
• I have run the unit tests locally
• I have run the valgrind memory tests locally
• All new and existing tests pass

[leo-aa88]

cursed strlen

[sonarqubecloud]

Quality Gate failed

Failed conditions
4.2% Duplication on New Code (required ≤ 3%)
C Reliability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

Catch issues before they fail your Quality Gate with our IDE extension SonarQube for IDE

[leo-aa88]

Quality Gate failed

Failed conditions 4.2% Duplication on New Code (required ≤ 3%) C Reliability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

Catch issues before they fail your Quality Gate with our IDE extension SonarQube for IDE

won't fix these