Rollup merge of rust-lang#123501 - Urgau:stabilize-check-cfg, r=petro…

…chenkov Stabilize checking of cfgs at compile-time: `--check-cfg` option This PR stabilize the `--check-cfg` CLI option of `rustc` (and `rustdoc`) 🎉. In particular this PR does two things: 1. it makes the `--check-cfg` option stable 2. and it moves the documentation to the stable books FCP: rust-lang#82450 (comment) Resolves rust-lang#82450 `@rustbot` labels S-blocked F-check-cfg r? `@petrochenkov`
matthiaskrgr · Apr 16, 2024 · 902487a · 902487a
2 parents b94a4e6 a20de73
commit 902487a
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diff --git a/compiler/rustc_lint/src/context/diagnostics/check_cfg.rs b/compiler/rustc_lint/src/context/diagnostics/check_cfg.rs
@@ -168,7 168,7 @@ pub(super) fn unexpected_cfg_name(
  diag.note("see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration");
  } else {
  diag.help(format!("to expect this configuration use `--check-cfg={inst}`"));
- diag.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
  diag.note("see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration");
  }
 }
 
@@ -272,6 272,6 @@ pub(super) fn unexpected_cfg_value(
  if !is_cfg_a_well_know_name {
  diag.help(format!("to expect this configuration use `--check-cfg={inst}`"));
  }
- diag.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
  diag.note("see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration");
  }
 }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
@@ -1373,7 1373,7 @@ pub fn rustc_short_optgroups() -> Vec<RustcOptGroup> {
  opt::flag_s("h", "help", "Display this message"),
  opt::multi_s("", "cfg", "Configure the compilation environment.
  SPEC supports the syntax `NAME[=\"VALUE\"]`.", "SPEC"),
- opt::multi("", "check-cfg", "Provide list of valid cfg options for checking", "SPEC"),
  opt::multi_s("", "check-cfg", "Provide list of expected cfgs for checking", "SPEC"),
  opt::multi_s(
  "L",
  "",

diff --git a/compiler/rustc_session/src/config/cfg.rs b/compiler/rustc_session/src/config/cfg.rs
@@ -257,7 257,7 @@ impl CheckCfg {
  // `tests/ui/check-cfg/well-known-values.rs` (in order to test the
  // expected values of the new config) and bless the all directory.
  //
- // Don't forget to update `src/doc/unstable-book/src/compiler-flags/check-cfg.md`
  // Don't forget to update `src/doc/rustc/src/check-cfg.md`
  // in the unstable book as well!
 
  ins!(sym::debug_assertions, no_values);

diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
@@ -77,6 77,7 @@
 - [Profile-guided Optimization](profile-guided-optimization.md)
 - [Instrumentation-based Code Coverage](instrument-coverage.md)
 - [Linker-plugin-based LTO](linker-plugin-lto.md)
 - [Checking conditional configurations](check-cfg.md)
 - [Exploit Mitigations](exploit-mitigations.md)
 - [Symbol Mangling](symbol-mangling/index.md)
  - [v0 Symbol Format](symbol-mangling/v0.md)

diff --git a/...able-book/src/compiler-flags/check-cfg.md → src/doc/rustc/src/check-cfg.md b/...able-book/src/compiler-flags/check-cfg.md → src/doc/rustc/src/check-cfg.md
@@ -1,10 1,4 @@
-# `check-cfg`
-
-The tracking issue for this feature is: [#82450](https://github.com/rust-lang/rust/issues/82450).
-
-------------------------
-
-This feature enables checking of conditional configuration.
 # Checking conditional configurations
 
 `rustc` accepts the `--check-cfg` option, which specifies whether to check conditions and how to
 check them. The `--check-cfg` option takes a value, called the _check cfg specification_.

diff --git a/src/doc/rustc/src/command-line-arguments.md b/src/doc/rustc/src/command-line-arguments.md
@@ -18,6 18,16 @@ The value can either be a single identifier or two identifiers separated by `=`.
 For examples, `--cfg 'verbose'` or `--cfg 'feature="serde"'`. These correspond
 to `#[cfg(verbose)]` and `#[cfg(feature = "serde")]` respectively.
 
 <a id="option-check-cfg"></a>
 ## `--check-cfg`: enables checking conditional configurations
 
 This flag will enable checking conditional configurations.
 Refer to the [Checking conditional configurations](check-cfg.md) of this book
 for further details and explanation.
 
 For examples, `--check-cfg 'cfg(verbose)'` or `--check-cfg 'cfg(feature, values("serde"))'`.
 These correspond to `#[cfg(verbose)]` and `#[cfg(feature = "serde")]` respectively.
 
 <a id="option-l-search-path"></a>
 ## `-L`: add a directory to the library search path
 

diff --git a/src/doc/rustdoc/src/command-line-arguments.md b/src/doc/rustdoc/src/command-line-arguments.md
@@ -131,6 131,20 @@ This flag accepts the same values as `rustc --cfg`, and uses it to configure
 compilation. The example above uses `feature`, but any of the `cfg` values
 are acceptable.
 
 ## `--check-cfg`: check configuration flags
 
 This flag accepts the same values as `rustc --check-cfg`, and uses it to
 check configuration flags.
 
 Using this flag looks like this:
 
 ```bash
 $ rustdoc src/lib.rs --check-cfg='cfg(my_cfg, values("foo", "bar"))'
 ```
 
 The example above check every well known names and values (`target_os`, `doc`, `test`, ...)
 and check the values of `my_cfg`: `foo` and `bar`.
 
 ## `--extern`: specify a dependency's location
 
 Using this flag looks like this:

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
@@ -618,22 618,6 @@ crate being documented (`foobar`) and a path to output the calls
 To scrape examples from test code, e.g. functions marked `#[test]`, then
 add the `--scrape-tests` flag.
 
-### `--check-cfg`: check configuration flags
-
- * Tracking issue: [#82450](https://github.com/rust-lang/rust/issues/82450)
-
-This flag accepts the same values as `rustc --check-cfg`, and uses it to check configuration flags.
-
-Using this flag looks like this:
-
-```bash
-$ rustdoc src/lib.rs -Z unstable-options \
- --check-cfg='cfg(feature, values("foo", "bar"))'
-```
-
-The example above check every well known names and values (`target_os`, `doc`, `test`, ...)
-and check the values of `feature`: `foo` and `bar`.
-
 ### `--generate-link-to-definition`: Generate links on types in source code
 
  * Tracking issue: [#89095](https://github.com/rust-lang/rust/issues/89095)

diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
@@ -60,11 60,8 @@ pub(crate) fn generate_args_file(file_path: &Path, options: &RustdocOptions) ->
  for cfg in &options.cfgs {
  content.push(format!("--cfg={cfg}"));
  }
- if !options.check_cfgs.is_empty() {
- content.push("-Zunstable-options".to_string());
- for check_cfg in &options.check_cfgs {
- content.push(format!("--check-cfg={check_cfg}"));
- }
  for check_cfg in &options.check_cfgs {
  content.push(format!("--check-cfg={check_cfg}"));
  }
 
  for lib_str in &options.lib_strs {

diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
@@ -242,7 242,7 @@ fn opts() -> Vec<RustcOptGroup> {
  o.optmulti("L", "library-path", "directory to add to crate search path", "DIR")
  }),
  stable("cfg", |o| o.optmulti("", "cfg", "pass a --cfg to rustc", "")),
- unstable("check-cfg", |o| o.optmulti("", "check-cfg", "pass a --check-cfg to rustc", "")),
  stable("check-cfg", |o| o.optmulti("", "check-cfg", "pass a --check-cfg to rustc", "")),
  stable("extern", |o| o.optmulti("", "extern", "pass an --extern to rustc", "NAME[=PATH]")),
  unstable("extern-html-root-url", |o| {
  o.optmulti(

diff --git a/tests/rustdoc-ui/check-cfg/check-cfg.rs → tests/rustdoc-ui/check-cfg.rs b/tests/rustdoc-ui/check-cfg/check-cfg.rs → tests/rustdoc-ui/check-cfg.rs
@@ -1,5 1,5 @@
 //@ check-pass
-//@ compile-flags: --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 /// uniz is nor a builtin nor pass as arguments so is unexpected
 #[cfg(uniz)]

diff --git a/tests/rustdoc-ui/check-cfg/check-cfg.stderr → tests/rustdoc-ui/check-cfg.stderr b/tests/rustdoc-ui/check-cfg/check-cfg.stderr → tests/rustdoc-ui/check-cfg.stderr
@@ -5,7 5,7 @@ LL | #[cfg(uniz)]
  | ^^^^ help: there is a config with a similar name: `unix`
  |
  = help: to expect this configuration use `--check-cfg=cfg(uniz)`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

diff --git a/tests/rustdoc-ui/check-cfg/check-cfg-test.stderr b/tests/rustdoc-ui/check-cfg/check-cfg-test.stderr
diff --git a/tests/rustdoc-ui/check-cfg/check-cfg-unstable.rs b/tests/rustdoc-ui/check-cfg/check-cfg-unstable.rs
diff --git a/tests/rustdoc-ui/check-cfg/check-cfg-unstable.stderr b/tests/rustdoc-ui/check-cfg/check-cfg-unstable.stderr
diff --git a/tests/rustdoc-ui/doctest/check-cfg-test.stderr b/tests/rustdoc-ui/doctest/check-cfg-test.stderr
@@ -6,7 6,7 @@ LL | #[cfg(feature = "invalid")]
  |
  = note: expected values for `feature` are: `test`
  = help: to expect this configuration use `--check-cfg=cfg(feature, values("invalid"))`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

diff --git a/tests/ui/check-cfg/allow-at-crate-level.rs b/tests/ui/check-cfg/allow-at-crate-level.rs
@@ -1,7 1,7 @@
 // This test check that #![allow(unexpected_cfgs)] works with --cfg
 //
 //@ check-pass
-//@ compile-flags: --cfg=unexpected --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --cfg=unexpected --check-cfg=cfg()
 
 #![allow(unexpected_cfgs)]
 

diff --git a/tests/ui/check-cfg/allow-macro-cfg.rs b/tests/ui/check-cfg/allow-macro-cfg.rs
@@ -1,7 1,7 @@
 // This test check that local #[allow(unexpected_cfgs)] works
 //
 //@ check-pass
-//@ compile-flags: --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 #[allow(unexpected_cfgs)]
 fn foo() {

diff --git a/tests/ui/check-cfg/allow-same-level.rs b/tests/ui/check-cfg/allow-same-level.rs
@@ -1,7 1,7 @@
 // This test check that #[allow(unexpected_cfgs)] doesn't work if put on the same level
 //
 //@ check-pass
-//@ compile-flags: --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 #[allow(unexpected_cfgs)]
 #[cfg(FALSE)]

diff --git a/tests/ui/check-cfg/allow-same-level.stderr b/tests/ui/check-cfg/allow-same-level.stderr
@@ -6,7 6,7 @@ LL | #[cfg(FALSE)]
  |
  = help: expected names are: `clippy`, `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
  = help: to expect this configuration use `--check-cfg=cfg(FALSE)`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

diff --git a/tests/ui/check-cfg/allow-top-level.rs b/tests/ui/check-cfg/allow-top-level.rs
@@ -1,7 1,7 @@
 // This test check that a top-level #![allow(unexpected_cfgs)] works
 //
 //@ check-pass
-//@ compile-flags: --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 #![allow(unexpected_cfgs)]
 

diff --git a/tests/ui/check-cfg/allow-upper-level.rs b/tests/ui/check-cfg/allow-upper-level.rs
@@ -1,7 1,7 @@
 // This test check that #[allow(unexpected_cfgs)] work if put on an upper level
 //
 //@ check-pass
-//@ compile-flags: --check-cfg=cfg() -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 #[allow(unexpected_cfgs)]
 mod aa {

diff --git a/tests/ui/check-cfg/cargo-feature.none.stderr b/tests/ui/check-cfg/cargo-feature.none.stderr
@@ -1,5 1,5 @@
 warning: unexpected `cfg` condition value: `serde`
- --> $DIR/cargo-feature.rs:14:7
  --> $DIR/cargo-feature.rs:13:7
  |
 LL | #[cfg(feature = "serde")]
  | ^^^^^^^^^^^^^^^^^ help: remove the condition
@@ -10,7 10,7 @@ LL | #[cfg(feature = "serde")]
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: (none)
- --> $DIR/cargo-feature.rs:18:7
  --> $DIR/cargo-feature.rs:17:7
  |
 LL | #[cfg(feature)]
  | ^^^^^^^ help: remove the condition
@@ -20,7 20,7 @@ LL | #[cfg(feature)]
  = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `tokio_unstable`
- --> $DIR/cargo-feature.rs:22:7
  --> $DIR/cargo-feature.rs:21:7
  |
 LL | #[cfg(tokio_unstable)]
  | ^^^^^^^^^^^^^^
@@ -30,7 30,7 @@ LL | #[cfg(tokio_unstable)]
  = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `CONFIG_NVME`
- --> $DIR/cargo-feature.rs:26:7
  --> $DIR/cargo-feature.rs:25:7
  |
 LL | #[cfg(CONFIG_NVME = "m")]
  | ^^^^^^^^^^^^^^^^^

diff --git a/tests/ui/check-cfg/cargo-feature.rs b/tests/ui/check-cfg/cargo-feature.rs
@@ -5,7 5,6 @@
 //@ check-pass
 //@ revisions: some none
 //@ rustc-env:CARGO_CRATE_NAME=foo
-//@ compile-flags: -Z unstable-options
 //@ [none]compile-flags: --check-cfg=cfg(feature,values())
 //@ [some]compile-flags: --check-cfg=cfg(feature,values("bitcode"))
 //@ [some]compile-flags: --check-cfg=cfg(CONFIG_NVME,values("y"))

diff --git a/tests/ui/check-cfg/cargo-feature.some.stderr b/tests/ui/check-cfg/cargo-feature.some.stderr
@@ -1,5 1,5 @@
 warning: unexpected `cfg` condition value: `serde`
- --> $DIR/cargo-feature.rs:14:7
  --> $DIR/cargo-feature.rs:13:7
  |
 LL | #[cfg(feature = "serde")]
  | ^^^^^^^^^^^^^^^^^
@@ -10,7 10,7 @@ LL | #[cfg(feature = "serde")]
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: (none)
- --> $DIR/cargo-feature.rs:18:7
  --> $DIR/cargo-feature.rs:17:7
  |
 LL | #[cfg(feature)]
  | ^^^^^^^- help: specify a config value: `= "bitcode"`
@@ -20,7 20,7 @@ LL | #[cfg(feature)]
  = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `tokio_unstable`
- --> $DIR/cargo-feature.rs:22:7
  --> $DIR/cargo-feature.rs:21:7
  |
 LL | #[cfg(tokio_unstable)]
  | ^^^^^^^^^^^^^^
@@ -30,7 30,7 @@ LL | #[cfg(tokio_unstable)]
  = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `m`
- --> $DIR/cargo-feature.rs:26:7
  --> $DIR/cargo-feature.rs:25:7
  |
 LL | #[cfg(CONFIG_NVME = "m")]
  | ^^^^^^^^^^^^^^---

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.rs b/tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.rs
@@ -2,7 2,6 @@
 // This test checks we won't suggest more than 3 span suggestions for cfg names
 //
 //@ check-pass
-//@ compile-flags: -Z unstable-options
 //@ compile-flags: --check-cfg=cfg(foo,values("value")) --check-cfg=cfg(bar,values("value")) --check-cfg=cfg(bee,values("value")) --check-cfg=cfg(cow,values("value"))
 
 #[cfg(value)]

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.stderr b/tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.stderr
@@ -1,12 1,12 @@
 warning: unexpected `cfg` condition name: `value`
- --> $DIR/cfg-value-for-cfg-name-duplicate.rs:8:7
  --> $DIR/cfg-value-for-cfg-name-duplicate.rs:7:7
  |
 LL | #[cfg(value)]
  | ^^^^^
  |
  = help: expected names are: `bar`, `bee`, `clippy`, `cow`, `debug_assertions`, `doc`, `doctest`, `foo`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
  = help: to expect this configuration use `--check-cfg=cfg(value)`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.rs b/tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.rs
@@ -2,7 2,6 @@
 // This test checks that when a single cfg has a value for user's specified name
 //
 //@ check-pass
-//@ compile-flags: -Z unstable-options
 //@ compile-flags: --check-cfg=cfg(foo,values("my_value")) --check-cfg=cfg(bar,values("my_value"))
 
 #[cfg(my_value)]

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.stderr b/tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.stderr
@@ -1,12 1,12 @@
 warning: unexpected `cfg` condition name: `my_value`
- --> $DIR/cfg-value-for-cfg-name-multiple.rs:8:7
  --> $DIR/cfg-value-for-cfg-name-multiple.rs:7:7
  |
 LL | #[cfg(my_value)]
  | ^^^^^^^^
  |
  = help: expected names are: `bar`, `clippy`, `debug_assertions`, `doc`, `doctest`, `foo`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
  = help: to expect this configuration use `--check-cfg=cfg(my_value)`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 help: found config with similar value
  |

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name.rs b/tests/ui/check-cfg/cfg-value-for-cfg-name.rs
@@ -3,7 3,6 @@
 // suggest to use `#[cfg(target_os = "linux")]` instead of `#[cfg(linux)]`
 //
 //@ check-pass
-//@ compile-flags: -Z unstable-options
 //@ compile-flags: --check-cfg=cfg()
 
 #[cfg(linux)]

diff --git a/tests/ui/check-cfg/cfg-value-for-cfg-name.stderr b/tests/ui/check-cfg/cfg-value-for-cfg-name.stderr
@@ -1,22 1,22 @@
 warning: unexpected `cfg` condition name: `linux`
- --> $DIR/cfg-value-for-cfg-name.rs:9:7
  --> $DIR/cfg-value-for-cfg-name.rs:8:7
  |
 LL | #[cfg(linux)]
  | ^^^^^ help: found config with similar value: `target_os = "linux"`
  |
  = help: expected names are: `clippy`, `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `sanitizer_cfi_generalize_pointers`, `sanitizer_cfi_normalize_integers`, `target_abi`, `target_arch`, `target_endian`, `target_env`, `target_family`, `target_feature`, `target_has_atomic`, `target_has_atomic_equal_alignment`, `target_has_atomic_load_store`, `target_os`, `target_pointer_width`, `target_thread_local`, `target_vendor`, `test`, `ub_checks`, `unix`, `windows`
  = help: to expect this configuration use `--check-cfg=cfg(linux)`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
  = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition name: `linux`
- --> $DIR/cfg-value-for-cfg-name.rs:14:7
  --> $DIR/cfg-value-for-cfg-name.rs:13:7
  |
 LL | #[cfg(linux = "os-name")]
  | ^^^^^^^^^^^^^^^^^
  |
  = help: to expect this configuration use `--check-cfg=cfg(linux, values("os-name"))`
- = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
  = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted