[dev.unified] cmd/compile: set base.Pos when process assignDef in Unified IR
CL 410343 changes Unified IR to visit LHS before RHS/X in assign/for
statement. Thus, it needs to set base.Pos before processing assignee
expression, so invalid type can be reported with correct position.
Updates #53058
Change-Id: Ic9f60cbf35c8bd71cb391e806396572c37811af7
Reviewed-on: https://go-review.googlesource.com/c/go/+/410794 Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>