From 41b69aae912aa9a1a8d5ed9518e73d136b42e7ca Mon Sep 17 00:00:00 2001 From: Urgau Date: Sat, 13 Jan 2024 12:18:51 +0100 Subject: Add way to express no-values with check-cfg --- .../unstable-book/src/compiler-flags/check-cfg.md | 25 +++++++++++----------- 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'src/doc') diff --git a/src/doc/unstable-book/src/compiler-flags/check-cfg.md b/src/doc/unstable-book/src/compiler-flags/check-cfg.md index 78bc8dceb78..bf83f6ad7c5 100644 --- a/src/doc/unstable-book/src/compiler-flags/check-cfg.md +++ b/src/doc/unstable-book/src/compiler-flags/check-cfg.md @@ -44,15 +44,20 @@ To enable checking of values, but to provide an *none*/empty set of expected val ```bash rustc --check-cfg 'cfg(name)' -rustc --check-cfg 'cfg(name, values())' rustc --check-cfg 'cfg(name, values(none()))' ``` -To enable checking of name but not values (i.e. unknown expected values), use this form: +To enable checking of name but not values, use one of these forms: -```bash -rustc --check-cfg 'cfg(name, values(any()))' -``` + - No expected values (_will lint on every value_): + ```bash + rustc --check-cfg 'cfg(name, values())' + ``` + + - Unknown expected values (_will never lint_): + ```bash + rustc --check-cfg 'cfg(name, values(any()))' + ``` To avoid repeating the same set of values, use this form: @@ -114,18 +119,14 @@ as argument to `--check-cfg`. This table describe the equivalence of a `--cfg` argument to a `--check-cfg` argument. | `--cfg` | `--check-cfg` | -|-----------------------------|----------------------------------------------------------| +|-------------------------------|------------------------------------------------------------| | *nothing* | *nothing* or `--check-cfg=cfg()` (to enable the checking) | -| `--cfg foo` | `--check-cfg=cfg(foo), --check-cfg=cfg(foo, values())` or `--check-cfg=cfg(foo, values(none()))` | +| `--cfg foo` | `--check-cfg=cfg(foo)` or `--check-cfg=cfg(foo, values(none()))` | | `--cfg foo=""` | `--check-cfg=cfg(foo, values(""))` | | `--cfg foo="bar"` | `--check-cfg=cfg(foo, values("bar"))` | | `--cfg foo="1" --cfg foo="2"` | `--check-cfg=cfg(foo, values("1", "2"))` | | `--cfg foo="1" --cfg bar="2"` | `--check-cfg=cfg(foo, values("1")) --check-cfg=cfg(bar, values("2"))` | -| `--cfg foo --cfg foo="bar"` | `--check-cfg=cfg(foo) --check-cfg=cfg(foo, values("bar"))` | - -NOTE: There is (currently) no way to express that a condition name is expected but no (!= none) -values are expected. Passing an empty `values()` means *(none)* in the sense of `#[cfg(foo)]` -with no value. Users are expected to NOT pass a `--check-cfg` with that condition name. +| `--cfg foo --cfg foo="bar"` | `--check-cfg=cfg(foo, values(none(), "bar"))` | ### Example: Cargo-like `feature` example -- cgit 1.4.1-3-g733a5