prevent ErrBadConn from driver.Open()

tjenkinson · tjenkinson · commit 590508ae35ac · 2019-10-26T19:56:56.000+01:00
because it seems this error is only meant to be internal, and if `ErrBadConn` is returned from here it can also be returned from the public api See some confusion about this here: go-sql-driver/mysql#1020 And a fix in the postgres driver here: lib/pq@04c77ed
diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
@@ -685,7 +685,11 @@ type dsnConnector struct {
 }
 
 func (t dsnConnector) Connect(_ context.Context) (driver.Conn, error) {
-	return t.driver.Open(t.dsn)
+	conn, err := t.driver.Open(t.dsn)
+	if err == driver.ErrBadConn {
+		return conn, fmt.Errorf("sql: driver open() returned ErrBadConn. ErrBadConn should only be returned from existing connections")
+	}
+	return conn, err
 }
 
 func (t dsnConnector) Driver() driver.Driver {

Original file line number	Diff line number	Diff line change
`@@ -685,7 +685,11 @@ type dsnConnector struct {`
`685`	`685`	`}`
`686`	`686`
`687`	`687`	`func (t dsnConnector) Connect(_ context.Context) (driver.Conn, error) {`
`688`		`- return t.driver.Open(t.dsn)`
	`688`	`+ conn, err := t.driver.Open(t.dsn)`
	`689`	`+ if err == driver.ErrBadConn {`
	`690`	`+ return conn, fmt.Errorf("sql: driver open() returned ErrBadConn. ErrBadConn should only be returned from existing connections")`
	`691`	`+ }`
	`692`	`+ return conn, err`
`689`	`693`	`}`
`690`	`694`
`691`	`695`	`func (t dsnConnector) Driver() driver.Driver {`