Stabilize -C overflow-checks

text/0000-stable-overflow-checks.md

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+- Feature Name: (fill me in with a unique ident, my_awesome_feature)
+- Start Date: (fill me in with today's date, YYYY-MM-DD)
+- RFC PR: (leave this empty)
+- Rust Issue: (leave this empty)
+
+# Summary
+[summary]: #summary
+
+Stabilize the `-C overflow-checks` command line argument.
+
+# Motivation
+[motivation]: #motivation
+
+This is an easy way to turn on overflow checks in release builds
+without otherwise turning on debug assertions, via the `-C
+debug-assertions` flag. In stable Rust today you can't get one without
+the other.
+
+Users can use the `-C overflow-checks` flag from their Cargo
+config to turn on overflow checks for an entire application.
+
+This flag, which accepts values of 'yes'/'no', 'on'/'off', is being
+renamed from `force-overflow-checks` because the `force` doesn't add
+anything that the 'yes'/'no'
+
+# Detailed design
+[design]: #detailed-design
+
+This is a stabilization RFC. The only steps will be to move
+`force-overflow-checks` from `-Z` to `-C`, renaming it to
+`overflow-checks`, and making it stable.
+
+# Drawbacks
+[drawbacks]: #drawbacks
+
+It's another rather ad-hoc flag for modifying code generation.
+
+Like other such flags, this applies to the entire code unit,
+regardless of monomorphizations. This means that code generation for a
+single function can be diferent based on which code unit its
+instantiated in.
+
+# Alternatives
+[alternatives]: #alternatives
+
+The flag could instead be tied to crates such that any time code from
+that crate is inlined/monomorphized it turns on overflow checks.
+
+We might also want a design that provides per-function control over
+overflow checks.
+
+# Unresolved questions
+[unresolved]: #unresolved-questions
+
+Cargo might also add a profile option like
+
+```toml
+[profile.dev]
+overflow-checks = true
+```
+
+This may also be accomplished by Cargo's pending support for passing
+arbitrary flags to rustc.
+