Fix ParamRef.Number always 0 for $N bind parameters

[notthelewis]

Summary

• parserLexer.Lex() in parser/parse.go copies lexer token data into the yacc semantic value via a switch on token type, but had no case PARAM:. The lexer (Lexer.lexParam) correctly scans a bind parameter's number into Token.Ival, but without a matching case it fell through to default, which only ever sets lval.str. lval.ival was left at its zero value, so every $N parsed as ParamRef{Number: 0} regardless of its actual position.
• Adds the missing case PARAM: lval.ival = tok.Ival.

Found while building a downstream tool that translates parsed Postgres SQL into another dialect and needed the actual parameter ordinals preserved.

Test plan

• Added parser/parsertest/paramref_test.go, covering a query with a repeated parameter ($1) and a second one ($2) across both the target list and a WHERE clause.
• go test ./... passes locally (all existing packages, including parsertest, pgregress, and tests/grammar).

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Fixes bind parameter number parsing in SQL parser.

The PR appears safe to merge; no actionable issue was identified.

Summary

The PR copies bind-parameter ordinals from lexer tokens into parser semantic values and adds a regression test for repeated and distinct parameters.

• $1 and $2 now retain their numbers in ParamRef.Number.
• The test checks parameters in a SELECT target list and WHERE clause.

_{Reviews (1) · Last reviewed commit: "Fix ParamRef.Number always 0 for $N bind..."}