Declaration in Stored Procedure is used to prepend further statements => Error

[windiana42]

Declarations in stored procedures can be defined using stored procedure arguments. Pytsql currently still copies them to prefix batches with isolate_top_level_statements=True which causes errors.
TSQL:

CREATE PROCEDURE CREATEALLDATES
    (
        @StartDate AS DATE, @EndDate AS DATE
    ) AS
    DECLARE @Current AS DATE = DATEADD(DD, 0, @StartDate); DROP TABLE IF EXISTS ##alldates CREATE TABLE ##alldates (
        dt DATE PRIMARY KEY
    ) WHILE @Current <= @EndDate BEGIN
    INSERT INTO ##alldates
    VALUES (@Current);
    SET @Current = DATEADD(DD, 1, @Current) -- add 1 to current day
END
GO
IF OBJECT_ID ( N'dbo.get_db_sampling_factor' , N'FN' ) IS NOT NULL DROP FUNCTION get_db_sampling_factor ;

Error:

sqlalchemy.exc.ProgrammingError: (pyodbc.ProgrammingError) ('42000', '[42000] [Microsoft][ODBC Driver 18 for SQL Server][SQL Server]Must declare the scalar variable "@StartDate". (137) (SQLExecDirectW)')
[SQL: DECLARE @Current AS DATE = DATEADD ( DD , 0 , @StartDate ) ; IF OBJECT_ID ( N'dbo.get_db_sampling_factor' , N'FN' ) IS NOT NULL DROP FUNCTION get_db_sampling_factor ;]

[windiana42]

I already located the problem near tsql.py:115:

        if isinstance(node, tsqlParser.Declare_statementContext):
            self.dynamics.extend(result)

[windiana42]

Here is a failing testcase: 58a61a7

[windiana42]

I am trying to reliably detect whether DECLARE is a top level statement. My current hypothesis is: a DECLARE statement is top level if the chain of parentCtx to the root (BatchContext) only includes Sql_clauseContext or Sql_clausesContext objects.

    @staticmethod
    def is_top_level_statement(node: ParserRuleContext):
        """Check wether node is a top level SQL statement."""
        cur = node.parentCtx
        while isinstance(cur, tsqlParser.Sql_clauseContext) or isinstance(cur, tsqlParser.Sql_clausesContext):
            cur = cur.parentCtx
        return isinstance(cur, tsqlParser.BatchContext)

[windiana42]

Why is the expectation that this SQL code should result in declare statement to be unconditionally copied?

def test_declaration_in_control_flow():
        seed = """
        IF 1 = 1
            DECLARE @A INT = 5
        SELECT * FROM x

If it is, we might have to parse the IF statement outcome:

        IF 1 = 0
            DECLARE @A INT = 5
        GO
        SELECT @A

The second with GO actually does not work in TSQL either. But this does:

DECLARE @A INT = 5
GO
SELECT @A