validateNoContextVariableAssignment() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateUseMemo.ts lines 183–214

function validateNoContextVariableAssignment(
  fn: HIRFunction,
  errors: CompilerError,
): void {
  const context = new Set(fn.context.map(place => place.identifier.id));
  for (const block of fn.body.blocks.values()) {
    for (const instr of block.instructions) {
      const value = instr.value;
      switch (value.kind) {
        case 'StoreContext': {
          if (context.has(value.lvalue.place.identifier.id)) {
            errors.pushDiagnostic(
              CompilerDiagnostic.create({
                category: ErrorCategory.UseMemo,
                reason:
                  'useMemo() callbacks may not reassign variables declared outside of the callback',
                description:
                  'useMemo() callbacks must be pure functions and cannot reassign variables defined outside of the callback function',
                suggestions: null,
              }).withDetails({
                kind: 'error',
                loc: value.lvalue.place.loc,
                message: 'Cannot reassign variable',
              }),
            );
          }
          break;
        }
      }
    }
  }
}