[release-branch.go1.20] cmd/compile: do not report division by error during typecheck
types2 have already errored about any spec-required overflows, and
division by zero. CL 469595 unintentionally fixed typecheck not to error
about overflows, but zero division is still be checked during tcArith.
This causes unsafe operations with variable size failed to compile,
instead of raising runtime error.
This CL also making change to typecheck.EvalConst, to stop evaluating
literal shifts or binary operators where {over,under}flows can happen.
For go1.21, typecheck.EvalConst is removed entirely, but that change is
too large to backport.
See discussion in CL 501735 for more details.
Fixes #60675
Change-Id: I7bea2821099556835c920713397f7c5d8a4025ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/501735
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/503855
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>