From 020bd6d323f20fa3c723320ee5b8484a8bcaa6cb Mon Sep 17 00:00:00 2001 From: Urgau Date: Mon, 30 Sep 2024 11:15:05 +0200 Subject: [PATCH] Improve `--print=check-cfg` documentation --- .../src/compiler-flags/print-check-cfg.md | 27 +++++++++++-------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/src/doc/unstable-book/src/compiler-flags/print-check-cfg.md b/src/doc/unstable-book/src/compiler-flags/print-check-cfg.md index ab63c986e85..8d314aa62d4 100644 --- a/src/doc/unstable-book/src/compiler-flags/print-check-cfg.md +++ b/src/doc/unstable-book/src/compiler-flags/print-check-cfg.md @@ -4,23 +4,28 @@ The tracking issue for this feature is: [#125704](https://github.com/rust-lang/r ------------------------ -This option of the `--print` flag print the list of expected cfgs. +This option of the `--print` flag print the list of all the expected cfgs. -This is related to the `--check-cfg` flag which allows specifying arbitrary expected +This is related to the [`--check-cfg` flag][check-cfg] which allows specifying arbitrary expected names and values. -This print option works similarly to `--print=cfg` (modulo check-cfg specifics): - - *check_cfg syntax*: *output of --print=check-cfg* - - `cfg(windows)`: `windows` - - `cfg(feature, values("foo", "bar"))`: `feature="foo"` and `feature="bar"` - - `cfg(feature, values(none(), ""))`: `feature` and `feature=""` - - `cfg(feature, values(any()))`: `feature=any()` - - `cfg(feature, values())`: `feature=` - - `cfg(any())`: `any()` - - *nothing*: `any()=any()` +This print option works similarly to `--print=cfg` (modulo check-cfg specifics). + +| `--check-cfg` | `--print=check-cfg` | +|-----------------------------------|-----------------------------| +| `cfg(foo)` | `foo` | +| `cfg(foo, values("bar"))` | `foo="bar"` | +| `cfg(foo, values(none(), "bar"))` | `foo` & `foo="bar"` | +| | *check-cfg specific syntax* | +| `cfg(foo, values(any())` | `foo=any()` | +| `cfg(foo, values())` | `foo=` | +| `cfg(any())` | `any()` | +| *none* | `any()=any()` | To be used like this: ```bash rustc --print=check-cfg -Zunstable-options lib.rs ``` + +[check-cfg]: https://doc.rust-lang.org/nightly/rustc/check-cfg.html