Feat: PostgreSQL capture correct line and column numbers for parse error

[StevenACoffman]

Fixes issue #263

Recently pg_query_go began to return the full structured error info instead of just error message in pganalyze/pg_query_go#76 which has released this functionality in v4.2.1. This sqlc PR #2288 updates to use v4.2.1 for pg_query_go.

After that PR is merged, sqlc will still not correctly display the line and column numbers, as pg_query_go parser.Error type has an Error() method that only includes the message, even though that same parser.Error type has all the other fields public.

This PR attempts to normalize the pg_query_go parser.Error type to a sqlc *sqlerr.Error.

• Parse here
  Appears to call:
• ParseToProtobuf here
• Appears to call https://github.com/pganalyze/pg_query_go/blob/7986455fd7e1752b8399930d49beac2e8a139bd5/parser/pg_query_parse.c#L110
• Appears to call pg_query_parse_protobuf here

So it looks like a PgQueryError error has:

		error = malloc(sizeof(PgQueryError));
		error->message   = strdup(error_data->message);
		error->filename  = strdup(error_data->filename);
		error->funcname  = strdup(error_data->funcname);
		error->context   = NULL;
		error->lineno    = error_data->lineno;
		error->cursorpos = error_data->cursorpos;

		result.error = error;	

Which then is read by

func newPgQueryError(errC *C.PgQueryError) *Error {
	err := &Error{
		Message:   C.GoString(errC.message),
		Lineno:    int(errC.lineno),
		Cursorpos: int(errC.cursorpos),
	}
	if errC.funcname != nil {
		err.Funcname = C.GoString(errC.funcname)
	}
	if errC.filename != nil {
		err.Filename = C.GoString(errC.filename)
	}
	if errC.context != nil {
		err.Context = C.GoString(errC.context)
	}
	return err
}

So the pg_query_go *parser.Error should be fully populated:

type Error struct {
	Message   string // exception message
	Funcname  string // source function of exception (e.g. SearchSysCache)
	Filename  string // source of exception (e.g. parse.l)
	Lineno    int    // source of exception (e.g. 104)
	Cursorpos int    // char in query at which exception occurred
	Context   string // additional context (optional, can be NULL)
}

Which is not exactly the same as the sqlc *sqlerror.Error type:

type Error struct {
	Err      error
	Code     string
	Message  string
	Location int
	Line     int
	Column   int
	// Hint     string
}

I believe that:

• pg_query_go*parser.Error.Lineno is equivalent to sqlc *sqlerror.Error.Line
• pg_query_go *parser.Error.Cursorpos is equivalent to sqlc *sqlerror.Error.Location
• pg_query_go *parser.Error.Message is equivalent to sqlc *sqlerror.Error.Message

[kyleconroy]

Thank you! This fixes a really old annoying issue with misleading line numbers.

[Jille]

Thank you indeed! That sure was annoying.