MDEV-38329 Named parameters in stored procedure CALL

[MooSayed1]

The Jira issue number for this PR is: MDEV-38329

Description

Stored routines currently require all arguments to be passed positionally.
When a routine has many parameters with defaults, there is no way to skip
middle parameters — only trailing ones can be omitted.

This patch adds named parameter invocation using the => syntax for both
stored procedures and stored functions:

CALL proc(a => 1, b => 2, c => 3);       -- all named
CALL proc(c => 3, a => 1, b => 2);       -- any order
CALL proc(1, b => 2, c => 3);            -- mixed positional + named
CALL proc(a => 1, c => 3);               -- skip middle param with default

SELECT func(a => 1, b => 2);             -- functions too
SELECT func(c => 3, a => 1, b => 2);     -- any order

This brings MariaDB in line with Oracle, PostgreSQL, SQL Server, and Firebird,
all of which already support named parameter invocation.

Parser changes (sql/sql_yacc.yy):

Added sp_cparam rule to accept ident ARROW_SYM expr alongside plain expr
in CALL argument lists, and a second udf_expr alternative for function calls.
In udf_expr both alternatives start with remember_name: it is a dummy in
the named-argument alternative (its value is unused), but it must be present
so both alternatives share the same empty-rule prefix — otherwise bison
reports a shift/reduce conflict on every token that can start an ident,
as it would have to decide whether to reduce remember_name before seeing
if ARROW_SYM follows. No new grammar conflicts are introduced.

Named arguments set IS_EXPLICIT_NAME on the Item and store the parameter
name in Item::name, reusing the mechanism that UDF named arguments (the
WL#1017 AS attribute syntax) already use — that syntax continues to work
and names arguments the same way. Positional arguments after a named argument
are rejected at parse time for CALL.

Reordering for procedures (sql/sp_head.cc):

In sp_head::execute_procedure(), before the binding loop, named arguments
are matched against sp_pcontext's formal parameter list by name and
reordered to their declared positions. Omitted parameters with defaults are
filled from sp_variable::default_value.

Reordering for functions (sql/item_func.cc, sql/item_create.cc):

In Item_func_sp::fix_fields(), after the sp_head is resolved, arguments
marked with IS_EXPLICIT_NAME are matched and reordered the same way. The
has_named_parameters() rejection in Create_sp_func::create_with_db() is
removed.

Error handling:

• Unknown parameter name (ER_SP_UNDECLARED_VAR)
• Duplicate parameter name, including positional/named collisions (ER_SP_DUP_PARAM)
• Missing required parameter without default (ER_SP_WRONG_NO_OF_ARGS)

Test suite change (mysql-test/main/udf.test):

An unknown attribute name on a stored function call, e.g. fn(MIN(b) xx),
is now reported as ER_SP_UNDECLARED_VAR instead of
ER_WRONG_PARAMETERS_TO_STORED_FCT, because stored functions now accept
named arguments.

Current status

Done:

• Parser: CALL proc(a => 1, b => 2) syntax accepted
• Named params for stored functions: SELECT func(a => 1)
• Mixed positional + named: CALL proc(1, b => 2)
• Parse-time rejection of positional after named
• Argument reordering in execute_procedure() and Item_func_sp::fix_fields()
• Default value filling for omitted parameters
• OUT/INOUT parameter support with named args (CALL p(x => @var))
• Prepared statement support (PREPARE stmt FROM 'CALL p(a => ?)', re-execution)
• Error detection: unknown name, duplicate name, missing required param
• MTR test coverage: nested calls, reserved words as param names, NULLs, expressions

Still working on:

• Defaults referencing earlier parameters (b INT DEFAULT a+1) fail with
  named invocation (CALL p(a => 5) → Unknown column 'a'), while positional
  CALL p(5) works. Filling from sp_variable::default_value in the caller's
  context bypasses sp_instr_set_default_param, which normally evaluates
  defaults inside the routine context based on
  sp_rcontext::m_inited_params_count. A fix keeping default evaluation
  inside the routine (making the inited-params tracking hole-aware for named
  args) is in progress.

This PR is a work in progress. Reviews and feedback on the current approach are welcome.

Release Notes

Stored procedures and stored functions now support named parameter invocation
using the => syntax. Arguments can be passed by name in any order, and
parameters with default values can be skipped: CALL proc(a => 1, c => 3),
SELECT func(b => 2, a => 1).

How can this PR be tested?

./mtr main.sp_named_params

The test covers:

• All positional (no regression)
• All named in declared order and different order, for CALL and SELECT
• Mixed positional + named
• Positional after named (syntax error)
• Unknown parameter name, duplicate name (named twice, positional then named)
• Default value: skip middle param, only required param, override all defaults
• Missing required parameter without default
• OUT/INOUT parameters with named args
• Prepared statements with named args, including re-execution
• Nested CALLs, reserved words as parameter names, NULL and expression values

Basing the PR against the correct MariaDB version

This is a new feature. The PR targets main.

PR quality check

• I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
• For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.

[Copilot]

Pull request overview

Adds support for invoking stored procedures with named arguments using the => syntax, allowing callers to reorder arguments and skip parameters that have defaults.

Changes:

• Parser: accept ident => expr entries in CALL (...) argument lists and reject positional arguments after any named one.
• Execution: reorder named CALL arguments to match formal parameter order and attempt to fill omitted parameters from routine defaults.
• Tests: add MTR coverage for procedure named args and (via existing AS-alias naming mechanism) stored function named args.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
sql/sql_yacc.yy	Extends CALL argument grammar to accept ident => expr and enforces “positional before named”.
sql/sql_lex.h	Adds LEX::has_named_call_param flag to track presence of named CALL args during parsing/execution.
sql/sql_lex.cc	Initializes has_named_call_param at CALL statement start.
sql/sp_head.cc	Reorders named CALL args to formal parameter positions and fills omitted params.
sql/item_func.cc	Adds stored-function argument reordering/default filling when named args are detected.
sql/item_create.cc	Removes prior rejection of named parameters in stored function calls (enabling AS-style named args).
mysql-test/main/sp_named_params.test	New MTR test for named procedure params + named stored-function params (via AS).
mysql-test/main/sp_named_params.result	Expected output for the new MTR test.

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[vuvova]

@MooSayed1 just FYI, this feature just missed 13.1, next deadline is 13.2, in 3 months.

[MooSayed1]

@vuvova OKay i'll try finish it before next release.

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