PRAGMA EXCEPTION_INIT Grammar Bug - Incorrect Use of decl_varname

Summary

PRAGMA EXCEPTION_INIT fails with "duplicate declaration" error when trying to associate an already-declared exception with an error code. This is caused by incorrect grammar production using decl_varname instead of any_identifier.

Test Case

DECLARE
  zero_excep exception;
  PRAGMA exception_init(zero_excep, -1476);
  var1 integer;
BEGIN
  var1 := 100 / 0;
exception
  WHEN zero_excep THEN
     raise info 'handle zero excep';
end;
/

Expected Behavior (Oracle 23c)

handle zero excep

PL/SQL procedure successfully completed.

Actual Behavior (IvorySQL)

ERROR:  duplicate declaration at or near "zero_excep"
LINE 3:   PRAGMA exception_init(zero_excep, -1476);
                                ^

Root Cause

In src/pl/plisql/src/pl_gram.y, the PRAGMA EXCEPTION_INIT production incorrectly uses decl_varname:

| K_PRAGMA K_EXCEPTION_INIT '(' decl_varname ',' ICONST ')' ';'

Problem: decl_varname enforces "name must NOT already be declared" and raises "duplicate declaration" error if the name exists.

But: PRAGMA EXCEPTION_INIT must reference an ALREADY declared exception variable.

This creates an impossible situation:

1. zero_excep exception; - Declares the exception
2. PRAGMA exception_init(zero_excep, ...) - ERROR: "duplicate declaration"!

Proposed Solution

Change the grammar to use any_identifier instead of decl_varname:

| K_PRAGMA K_EXCEPTION_INIT '(' any_identifier ',' exception_error_code ')' ';'

This allows PRAGMA EXCEPTION_INIT to reference existing exception variables without triggering duplicate declaration checks.

References

• Upstream PR review: feat: add user-defined EXCEPTION support for PL/iSQL IvorySQL/IvorySQL#972 (comment)
• CodeRabbit review identified the same issue: feat: add user-defined EXCEPTION support for PL/iSQL IvorySQL/IvorySQL#972 (comment)
• Test branch: test/user-exception

Related Issues

This blocks proper Oracle PL/SQL compatibility for user-defined exceptions with custom error codes.