The standard way for this with current tools is to have the formatter/linter make the changes but exit with a non-zero status, failing the hook. Then the person reviews the changes, stages, and commits. (That's what our setup currently has `tofu fmt` do.)
But if you don't want to have hooks modify code, in a case like this you can also just use `tofu validate`. Our setup does `tflint` and `tofu validate` for this purpose, neither of which modifies the code.
This is also, of course, a reasonable place to have people use `tofu plan`. It you want bad code to fail as quickly as possible, you can do:
tflint -> tfsec -> tofu validate -> tofu plan
That'll catch everything Terraform will let you catch before deploy time— most of it very quickly— without modifying any code.
