Overloading in package routines

Implement overloading in package functions and procedures, to make it possible to declare routines with the same name but with:

• Different number of arguments
• The same number of arguments, but with different argument types

to make possible declarations like this:

SET sql_mode=ORACLE;

DELIMITER $$

CREATE OR REPLACE PACKAGE pkg1

AS

  FUNCTION f1() RETURN INT;

  FUNCTION f1(a INT) RETURN INT;

  FUNCTION f1(a TEXT) RETURN INT;

  FUNCTION f1(a INT, b TEXT) RETURN INT;

  FUNCTION f1(a TEXT, b INT) RETURN INT;

END;

$$

Overloading will work in all sql_mode's using their respective syntax.

The scope

This task is only about overloading in package routines.

Overloading in schema routines will be done separately, because it'll need more efforts:

• Changes in mysql.proc.specific_name
• Changes in INFORMATION_SCHEMA.ROUTINES.SPECIFIC_NAME.

These coulumns should return something similar to C++ mangled function names - a combination of the name and the signature for parameters

Relation to MDEV-18951

This task does not duplicate any functionality described in MDEV-18951, which is not about overloading but is rather about template-style functions, similar to C++ templates.

In terms of C++,

• MDEV-18951 is very close to:

  template<typename X>

  bool lt(const X a, const X b)

  {

  return a < b;

  };

• MDEV-34484 is about:

  bool lt(const double a, const double b)

  {

  return a < b;

  };

  bool lt(const int b, const int b)

  {

  return a < b;

  };

Although, both approaches effectively implement the same functionality, they use different instrumentation to achieve it.