Auto merge of #118213 - Urgau:check-cfg-diagnostics-rustc-cargo, r=petrochenkov

Add more suggestions to unexpected cfg names and values

This pull request adds more suggestion to unexpected cfg names and values diagnostics:
 - it first adds a links to the [rustc unstable book](https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html) or the [Cargo reference](https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg), depending if rustc is invoked by Cargo
 - it secondly adds a suggestion on how to expect the cfg name or value:
    *excluding well known names and values*
    - for Cargo: it suggest using a feature or `cargo:rust-check-cfg` in build script
    - for rustc: it suggest using `--check-cfg` (with the correct invocation)

Those diagnostics improvements are directed towards enabling users to fix the issue if the previous suggestions weren't good enough.

r? `@petrochenkov`

Author: bors

compiler/rustc_lint/src/context.rs

@@ -706,9 +706,13 @@ pub trait LintContext {
                 },
                 BuiltinLintDiagnostics::UnexpectedCfgName((name, name_span), value) => {
                     let possibilities: Vec<Symbol> = sess.parse_sess.check_config.expecteds.keys().copied().collect();
+                    let is_from_cargo = std::env::var_os("CARGO").is_some();
+                    let mut is_feature_cfg = name == sym::feature;
 
+                    if is_feature_cfg && is_from_cargo {
+                        db.help("consider defining some features in `Cargo.toml`");
                     // Suggest the most probable if we found one
-                    if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) {
+                    } else if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) {
                         if let Some(ExpectedValues::Some(best_match_values)) =
                             sess.parse_sess.check_config.expecteds.get(&best_match) {
                             let mut possibilities = best_match_values.iter()
@@ -741,8 +745,8 @@ pub trait LintContext {
                         } else {
                             db.span_suggestion(name_span, "there is a config with a similar name", best_match, Applicability::MaybeIncorrect);
                         }
-                    } else if name == sym::feature && std::env::var_os("CARGO").is_some() {
-                        db.help("consider defining some features in `Cargo.toml`");
+
+                        is_feature_cfg |= best_match == sym::feature;
                     } else if !possibilities.is_empty() {
                         let mut possibilities = possibilities.iter()
                             .map(Symbol::as_str)
@@ -756,6 +760,23 @@ pub trait LintContext {
                         // once.
                         db.help_once(format!("expected names are: `{possibilities}`"));
                     }
+
+                    let inst = if let Some((value, _value_span)) = value {
+                        let pre = if is_from_cargo { "\\" } else { "" };
+                        format!("cfg({name}, values({pre}\"{value}{pre}\"))")
+                    } else {
+                        format!("cfg({name})")
+                    };
+
+                    if is_from_cargo {
+                        if !is_feature_cfg {
+                            db.help(format!("consider using a Cargo feature instead or adding `println!(\"cargo:rustc-check-cfg={inst}\");` to the top of a `build.rs`"));
+                        }
+                        db.note("see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration");
+                    } else {
+                        db.help(format!("to expect this configuration use `--check-cfg={inst}`"));
+                        db.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
+                    }
                 },
                 BuiltinLintDiagnostics::UnexpectedCfgValue((name, name_span), value) => {
                     let Some(ExpectedValues::Some(values)) = &sess.parse_sess.check_config.expecteds.get(&name) else {
@@ -767,6 +788,7 @@ pub trait LintContext {
                         .copied()
                         .flatten()
                         .collect();
+                    let is_from_cargo = std::env::var_os("CARGO").is_some();
 
                     // Show the full list if all possible values for a given name, but don't do it
                     // for names as the possibilities could be very long
@@ -787,6 +809,8 @@ pub trait LintContext {
                                 db.span_suggestion(value_span, "there is a expected value with a similar name", format!("\"{best_match}\""), Applicability::MaybeIncorrect);
 
                             }
+                        } else if name == sym::feature && is_from_cargo {
+                            db.help(format!("consider defining `{name}` as feature in `Cargo.toml`"));
                         } else if let &[first_possibility] = &possibilities[..] {
                             db.span_suggestion(name_span.shrink_to_hi(), "specify a config value", format!(" = \"{first_possibility}\""), Applicability::MaybeIncorrect);
                         }
@@ -796,6 +820,27 @@ pub trait LintContext {
                             db.span_suggestion(name_span.shrink_to_hi().to(value_span), "remove the value", "", Applicability::MaybeIncorrect);
                         }
                     }
+
+                    let inst = if let Some((value, _value_span)) = value {
+                        let pre = if is_from_cargo { "\\" } else { "" };
+                        format!("cfg({name}, values({pre}\"{value}{pre}\"))")
+                    } else {
+                        format!("cfg({name})")
+                    };
+
+                    if is_from_cargo {
+                        if name == sym::feature {
+                            if let Some((value, _value_span)) = value {
+                                db.help(format!("consider adding `{value}` as a feature in `Cargo.toml`"));
+                            }
+                        } else {
+                            db.help(format!("consider using a Cargo feature instead or adding `println!(\"cargo:rustc-check-cfg={inst}\");` to the top of a `build.rs`"));
+                        }
+                        db.note("see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration");
+                    } else {
+                        db.help(format!("to expect this configuration use `--check-cfg={inst}`"));
+                        db.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
+                    }
                 },
                 BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(new_span, suggestion) => {
                     db.multipart_suggestion(

tests/rustdoc-ui/check-cfg/check-cfg.stderr

@@ -4,6 +4,8 @@ warning: unexpected `cfg` condition name: `uniz`
 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: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/rustdoc-ui/doctest/check-cfg-test.stderr

@@ -5,6 +5,8 @@ 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: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/allow-same-level.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(FALSE)]
    |       ^^^^^
    |
    = help: expected names are: `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`, `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: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/cargo-feature.none.stderr

@@ -0,0 +1,31 @@
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/cargo-feature.rs:13:7
+   |
+LL | #[cfg(feature = "serde")]
+   |       ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider defining some features in `Cargo.toml`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: unexpected `cfg` condition name: `tokio_unstable`
+  --> $DIR/cargo-feature.rs:18:7
+   |
+LL | #[cfg(tokio_unstable)]
+   |       ^^^^^^^^^^^^^^
+   |
+   = help: expected names are: `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`, `unix`, `windows`
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(tokio_unstable)");` to the top of a `build.rs`
+   = 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:22:7
+   |
+LL | #[cfg(CONFIG_NVME = "m")]
+   |       ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(CONFIG_NVME, values(\"m\"))");` to the top of a `build.rs`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+
+warning: 3 warnings emitted
+

tests/ui/check-cfg/cargo-feature.rs

@@ -3,12 +3,25 @@
 // list of all the expected names
 //
 // check-pass
+// revisions: some none
 // rustc-env:CARGO=/usr/bin/cargo
 // compile-flags: --check-cfg=cfg() -Z unstable-options
-// error-pattern:Cargo.toml
+// [some]compile-flags: --check-cfg=cfg(feature,values("bitcode"))
+// [some]compile-flags: --check-cfg=cfg(CONFIG_NVME,values("y"))
+// [none]error-pattern:Cargo.toml
 
 #[cfg(feature = "serde")]
-//~^ WARNING unexpected `cfg` condition name
+//[none]~^ WARNING unexpected `cfg` condition name
+//[some]~^^ WARNING unexpected `cfg` condition value
 fn ser() {}
 
+#[cfg(tokio_unstable)]
+//~^ WARNING unexpected `cfg` condition name
+fn tokio() {}
+
+#[cfg(CONFIG_NVME = "m")]
+//[none]~^ WARNING unexpected `cfg` condition name
+//[some]~^^ WARNING unexpected `cfg` condition value
+fn tokio() {}
+
 fn main() {}

tests/ui/check-cfg/cargo-feature.some.stderr

@@ -0,0 +1,35 @@
+warning: unexpected `cfg` condition value: `serde`
+  --> $DIR/cargo-feature.rs:13:7
+   |
+LL | #[cfg(feature = "serde")]
+   |       ^^^^^^^^^^^^^^^^^
+   |
+   = note: expected values for `feature` are: `bitcode`
+   = help: consider adding `serde` as a feature in `Cargo.toml`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: unexpected `cfg` condition name: `tokio_unstable`
+  --> $DIR/cargo-feature.rs:18:7
+   |
+LL | #[cfg(tokio_unstable)]
+   |       ^^^^^^^^^^^^^^
+   |
+   = help: expected names are: `CONFIG_NVME`, `debug_assertions`, `doc`, `doctest`, `feature`, `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`, `unix`, `windows`
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(tokio_unstable)");` to the top of a `build.rs`
+   = 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:22:7
+   |
+LL | #[cfg(CONFIG_NVME = "m")]
+   |       ^^^^^^^^^^^^^^---
+   |                     |
+   |                     help: there is a expected value with a similar name: `"y"`
+   |
+   = note: expected values for `CONFIG_NVME` are: `y`
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(CONFIG_NVME, values(\"m\"))");` to the top of a `build.rs`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+
+warning: 3 warnings emitted
+

tests/ui/check-cfg/cargo-feature.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(target(os = "linux", architecture = "arm"))]
    |                            ^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(target_architecture, values("arm"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/compact-names.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(target(os = "linux", pointer_width = "X"))]
    |                            ^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_pointer_width` are: `16`, `32`, `64`
+   = help: to expect this configuration use `--check-cfg=cfg(target_pointer_width, values("X"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/compact-values.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(my_cfg)]
    |       ^^^^^^
    |
    = note: expected values for `my_cfg` are: `bar`, `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(my_cfg)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `unk`
@@ -14,6 +16,8 @@ LL | #[cfg(my_cfg = "unk")]
    |       ^^^^^^^^^^^^^^
    |
    = note: expected values for `my_cfg` are: `bar`, `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(my_cfg, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted
 

tests/ui/check-cfg/concat-values.stderr

@@ -0,0 +1,71 @@
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:7:7
+   |
+LL | #[cfg(featur)]
+   |       ^^^^^^ help: there is a config with a similar name: `feature`
+   |
+   = help: expected values for `feature` are: `foo`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:11:7
+   |
+LL | #[cfg(featur = "foo")]
+   |       ^^^^^^^^^^^^^^
+   |
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+help: there is a config with a similar name and value
+   |
+LL | #[cfg(feature = "foo")]
+   |       ~~~~~~~
+
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:15:7
+   |
+LL | #[cfg(featur = "fo")]
+   |       ^^^^^^^^^^^^^
+   |
+   = help: expected values for `feature` are: `foo`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+help: there is a config with a similar name and different values
+   |
+LL | #[cfg(feature = "foo")]
+   |       ~~~~~~~~~~~~~~~
+
+warning: unexpected `cfg` condition name: `no_value`
+  --> $DIR/diagnotics.rs:22:7
+   |
+LL | #[cfg(no_value)]
+   |       ^^^^^^^^ help: there is a config with a similar name: `no_values`
+   |
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(no_value)");` to the top of a `build.rs`
+   = 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: `no_value`
+  --> $DIR/diagnotics.rs:26:7
+   |
+LL | #[cfg(no_value = "foo")]
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(no_value, values(\"foo\"))");` to the top of a `build.rs`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+help: there is a config with a similar name and no value
+   |
+LL | #[cfg(no_values)]
+   |       ~~~~~~~~~
+
+warning: unexpected `cfg` condition value: `bar`
+  --> $DIR/diagnotics.rs:30:7
+   |
+LL | #[cfg(no_values = "bar")]
+   |       ^^^^^^^^^--------
+   |                |
+   |                help: remove the value
+   |
+   = note: no expected value for `no_values`
+   = help: consider using a Cargo feature instead or adding `println!("cargo:rustc-check-cfg=cfg(no_values, values(\"bar\"))");` to the top of a `build.rs`
+   = note: see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration
+
+warning: 6 warnings emitted
+

tests/ui/check-cfg/diagnotics.cargo.stderr

@@ -1,4 +1,7 @@
 // check-pass
+// revisions: cargo rustc
+// [rustc]unset-rustc-env:CARGO
+// [cargo]rustc-env:CARGO=/usr/bin/cargo
 // compile-flags: --check-cfg=cfg(feature,values("foo")) --check-cfg=cfg(no_values) -Z unstable-options
 
 #[cfg(featur)]

tests/ui/check-cfg/diagnotics.rs

@@ -0,0 +1,74 @@
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:7:7
+   |
+LL | #[cfg(featur)]
+   |       ^^^^^^ help: there is a config with a similar name: `feature`
+   |
+   = help: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(featur)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:11:7
+   |
+LL | #[cfg(featur = "foo")]
+   |       ^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(featur, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+help: there is a config with a similar name and value
+   |
+LL | #[cfg(feature = "foo")]
+   |       ~~~~~~~
+
+warning: unexpected `cfg` condition name: `featur`
+  --> $DIR/diagnotics.rs:15:7
+   |
+LL | #[cfg(featur = "fo")]
+   |       ^^^^^^^^^^^^^
+   |
+   = help: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(featur, values("fo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+help: there is a config with a similar name and different values
+   |
+LL | #[cfg(feature = "foo")]
+   |       ~~~~~~~~~~~~~~~
+
+warning: unexpected `cfg` condition name: `no_value`
+  --> $DIR/diagnotics.rs:22:7
+   |
+LL | #[cfg(no_value)]
+   |       ^^^^^^^^ help: there is a config with a similar name: `no_values`
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(no_value)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+
+warning: unexpected `cfg` condition name: `no_value`
+  --> $DIR/diagnotics.rs:26:7
+   |
+LL | #[cfg(no_value = "foo")]
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(no_value, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+help: there is a config with a similar name and no value
+   |
+LL | #[cfg(no_values)]
+   |       ~~~~~~~~~
+
+warning: unexpected `cfg` condition value: `bar`
+  --> $DIR/diagnotics.rs:30:7
+   |
+LL | #[cfg(no_values = "bar")]
+   |       ^^^^^^^^^--------
+   |                |
+   |                help: remove the value
+   |
+   = note: no expected value for `no_values`
+   = help: to expect this configuration use `--check-cfg=cfg(no_values, values("bar"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
+
+warning: 6 warnings emitted
+

tests/ui/check-cfg/diagnotics.rustc.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(unknown_key, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `value`
@@ -16,18 +18,26 @@ LL | #[cfg(test = "value")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `feature`
   --> $DIR/exhaustive-names-values.rs:18:7
    |
 LL | #[cfg(feature = "unk")]
    |       ^^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `feature`
   --> $DIR/exhaustive-names-values.rs:25:7
    |
 LL | #[cfg(feature = "std")]
    |       ^^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("std"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 4 warnings emitted
 

tests/ui/check-cfg/diagnotics.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(unknown_key, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `value`
@@ -16,6 +18,8 @@ LL | #[cfg(test = "value")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `unk`
   --> $DIR/exhaustive-names-values.rs:18:7
@@ -24,6 +28,8 @@ LL | #[cfg(feature = "unk")]
    |       ^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `std`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 3 warnings emitted
 

tests/ui/check-cfg/exhaustive-names-values.empty_cfg.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(unknown_key, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `value`
@@ -16,6 +18,8 @@ LL | #[cfg(test = "value")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `unk`
   --> $DIR/exhaustive-names-values.rs:18:7
@@ -24,6 +28,8 @@ LL | #[cfg(feature = "unk")]
    |       ^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `std`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 3 warnings emitted
 

tests/ui/check-cfg/exhaustive-names-values.empty_names_values.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(unknown_key, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/exhaustive-names-values.feature.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(test = "value")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/exhaustive-names-values.full.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(test = "value")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/exhaustive-names.exhaustive_names.stderr

@@ -4,6 +4,8 @@ warning: unexpected `cfg` condition name: `widnows`
 LL | #[cfg(widnows)]
    |       ^^^^^^^ help: there is a config with a similar name: `windows`
    |
+   = help: to expect this configuration use `--check-cfg=cfg(widnows)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: (none)
@@ -13,6 +15,8 @@ LL | #[cfg(feature)]
    |       ^^^^^^^- help: specify a config value: `= "foo"`
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `bar`
   --> $DIR/mix.rs:23:7
@@ -21,6 +25,8 @@ LL | #[cfg(feature = "bar")]
    |       ^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("bar"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:27:7
@@ -29,6 +35,8 @@ LL | #[cfg(feature = "zebra")]
    |       ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `uu`
   --> $DIR/mix.rs:31:12
@@ -37,12 +45,17 @@ LL | #[cfg_attr(uu, test)]
    |            ^^
    |
    = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(uu)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `widnows`
   --> $DIR/mix.rs:40:10
    |
 LL |     cfg!(widnows);
    |          ^^^^^^^ help: there is a config with a similar name: `windows`
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(widnows)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `bar`
   --> $DIR/mix.rs:43:10
@@ -51,6 +64,8 @@ LL |     cfg!(feature = "bar");
    |          ^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("bar"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:45:10
@@ -59,24 +74,35 @@ LL |     cfg!(feature = "zebra");
    |          ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:47:10
    |
 LL |     cfg!(xxx = "foo");
    |          ^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:49:10
    |
 LL |     cfg!(xxx);
    |          ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:51:14
    |
 LL |     cfg!(any(xxx, windows));
    |              ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `bad`
   --> $DIR/mix.rs:53:14
@@ -85,42 +111,62 @@ LL |     cfg!(any(feature = "bad", windows));
    |              ^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("bad"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:55:23
    |
 LL |     cfg!(any(windows, xxx));
    |                       ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:57:20
    |
 LL |     cfg!(all(unix, xxx));
    |                    ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `aa`
   --> $DIR/mix.rs:59:14
    |
 LL |     cfg!(all(aa, bb));
    |              ^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(aa)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `bb`
   --> $DIR/mix.rs:59:18
    |
 LL |     cfg!(all(aa, bb));
    |                  ^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(bb)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `aa`
   --> $DIR/mix.rs:62:14
    |
 LL |     cfg!(any(aa, bb));
    |              ^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(aa)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `bb`
   --> $DIR/mix.rs:62:18
    |
 LL |     cfg!(any(aa, bb));
    |                  ^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(bb)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:65:20
@@ -129,12 +175,17 @@ LL |     cfg!(any(unix, feature = "zebra"));
    |                    ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:67:14
    |
 LL |     cfg!(any(xxx, feature = "zebra"));
    |              ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:67:19
@@ -143,18 +194,26 @@ LL |     cfg!(any(xxx, feature = "zebra"));
    |                   ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:70:14
    |
 LL |     cfg!(any(xxx, unix, xxx));
    |              ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `xxx`
   --> $DIR/mix.rs:70:25
    |
 LL |     cfg!(any(xxx, unix, xxx));
    |                         ^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(xxx)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:73:14
@@ -163,6 +222,8 @@ LL |     cfg!(all(feature = "zebra", feature = "zebra", feature = "zebra"));
    |              ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:73:33
@@ -171,6 +232,8 @@ LL |     cfg!(all(feature = "zebra", feature = "zebra", feature = "zebra"));
    |                                 ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `zebra`
   --> $DIR/mix.rs:73:52
@@ -179,6 +242,8 @@ LL |     cfg!(all(feature = "zebra", feature = "zebra", feature = "zebra"));
    |                                                    ^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `foo`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("zebra"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 26 warnings emitted
 

tests/ui/check-cfg/exhaustive-names.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(feature = "foo")]
    |              help: remove the value
    |
    = note: no expected value for `feature`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `foo`
@@ -18,6 +20,8 @@ LL | #[cfg(test = "foo")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted
 

tests/ui/check-cfg/exhaustive-values.empty_cfg.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(feature = "foo")]
    |              help: remove the value
    |
    = note: no expected value for `feature`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `foo`
@@ -18,6 +20,8 @@ LL | #[cfg(test = "foo")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted
 

tests/ui/check-cfg/exhaustive-values.without_names.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(feature = "foo")]
    |              help: remove the value
    |
    = note: no expected value for `feature`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `foo`
@@ -18,6 +20,8 @@ LL | #[cfg(test = "foo")]
    |           help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted
 

tests/ui/check-cfg/mix.cfg.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(a = "unk")]
    |       ^^^^^^^^^
    |
    = note: expected values for `a` are: (none), `b`
+   = help: to expect this configuration use `--check-cfg=cfg(a, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/mix.stderr

@@ -5,6 +5,8 @@ LL | #[cfg(a = "unk")]
    |       ^^^^^^^^^
    |
    = note: expected values for `a` are: (none), `b`
+   = help: to expect this configuration use `--check-cfg=cfg(a, values("unk"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/no-expected-values.empty.stderr

@@ -5,6 +5,8 @@ LL |     #[cfg(crossbeam_loom)]
    |           ^^^^^^^^^^^^^^
    |
    = help: expected names are: `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(crossbeam_loom)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/no-expected-values.mixed.stderr

@@ -4,6 +4,8 @@ warning: unexpected `cfg` condition name: `widnows`
 LL | #[cfg(widnows)]
    |       ^^^^^^^ help: there is a config with a similar name: `windows`
    |
+   = help: to expect this configuration use `--check-cfg=cfg(widnows)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/no-expected-values.simple.stderr

@@ -7,6 +7,8 @@ LL | #[cfg(feature = "sedre")]
    |                 help: there is a expected value with a similar name: `"serde"`
    |
    = note: expected values for `feature` are: `full`, `serde`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("sedre"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `rand`
@@ -16,6 +18,8 @@ LL | #[cfg(feature = "rand")]
    |       ^^^^^^^^^^^^^^^^
    |
    = note: expected values for `feature` are: `full`, `serde`
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("rand"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 2 warnings emitted
 

tests/ui/check-cfg/order-independant.values_after.stderr

@@ -4,6 +4,8 @@ warning: unexpected `cfg` condition name: `target_oz`
 LL | #[cfg(target_oz = "linux")]
    |       ^^^^^^^^^^^^^^^^^^^
    |
+   = help: to expect this configuration use `--check-cfg=cfg(target_oz, values("linux"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 help: there is a config with a similar name and value
    |
@@ -17,18 +19,26 @@ LL | #[cfg(features = "foo")]
    |       ^^^^^^^^^^^^^^^^
    |
    = help: expected names are: `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`, `unix`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(features, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `feature`
   --> $DIR/well-known-names.rs:17:7
    |
 LL | #[cfg(feature = "foo")]
    |       ^^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(feature, values("foo"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition name: `uniw`
   --> $DIR/well-known-names.rs:21:7
    |
 LL | #[cfg(uniw)]
    |       ^^^^ help: there is a config with a similar name: `unix`
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(uniw)`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 4 warnings emitted
 

tests/ui/check-cfg/order-independant.values_before.stderr

@@ -7,6 +7,8 @@ LL |     debug_assertions = "_UNEXPECTED_VALUE",
    |                     help: remove the value
    |
    = note: no expected value for `debug_assertions`
+   = help: to expect this configuration use `--check-cfg=cfg(debug_assertions, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
@@ -18,6 +20,8 @@ LL |     doc = "_UNEXPECTED_VALUE",
    |        help: remove the value
    |
    = note: no expected value for `doc`
+   = help: to expect this configuration use `--check-cfg=cfg(doc, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:30:5
@@ -28,6 +32,8 @@ LL |     doctest = "_UNEXPECTED_VALUE",
    |            help: remove the value
    |
    = note: no expected value for `doctest`
+   = help: to expect this configuration use `--check-cfg=cfg(doctest, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:32:5
@@ -38,6 +44,8 @@ LL |     miri = "_UNEXPECTED_VALUE",
    |         help: remove the value
    |
    = note: no expected value for `miri`
+   = help: to expect this configuration use `--check-cfg=cfg(miri, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:34:5
@@ -48,6 +56,8 @@ LL |     overflow_checks = "_UNEXPECTED_VALUE",
    |                    help: remove the value
    |
    = note: no expected value for `overflow_checks`
+   = help: to expect this configuration use `--check-cfg=cfg(overflow_checks, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:36:5
@@ -56,6 +66,8 @@ LL |     panic = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `panic` are: `abort`, `unwind`
+   = help: to expect this configuration use `--check-cfg=cfg(panic, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:38:5
@@ -66,6 +78,8 @@ LL |     proc_macro = "_UNEXPECTED_VALUE",
    |               help: remove the value
    |
    = note: no expected value for `proc_macro`
+   = help: to expect this configuration use `--check-cfg=cfg(proc_macro, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:40:5
@@ -74,6 +88,8 @@ LL |     relocation_model = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `relocation_model` are: `dynamic-no-pic`, `pic`, `pie`, `ropi`, `ropi-rwpi`, `rwpi`, `static`
+   = help: to expect this configuration use `--check-cfg=cfg(relocation_model, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:42:5
@@ -82,6 +98,8 @@ LL |     sanitize = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `sanitize` are: `address`, `cfi`, `hwaddress`, `kcfi`, `kernel-address`, `leak`, `memory`, `memtag`, `safestack`, `shadow-call-stack`, `thread`
+   = help: to expect this configuration use `--check-cfg=cfg(sanitize, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:44:5
@@ -90,6 +108,8 @@ LL |     target_abi = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_abi` are: ``, `abi64`, `abiv2`, `abiv2hf`, `eabi`, `eabihf`, `elf`, `fortanix`, `ilp32`, `llvm`, `macabi`, `sim`, `softfloat`, `spe`, `uwp`, `vec-extabi`, `x32`
+   = help: to expect this configuration use `--check-cfg=cfg(target_abi, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:46:5
@@ -98,6 +118,8 @@ LL |     target_arch = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_arch` are: `aarch64`, `arm`, `avr`, `bpf`, `csky`, `hexagon`, `loongarch64`, `m68k`, `mips`, `mips32r6`, `mips64`, `mips64r6`, `msp430`, `nvptx64`, `powerpc`, `powerpc64`, `riscv32`, `riscv64`, `s390x`, `sparc`, `sparc64`, `wasm32`, `wasm64`, `x86`, `x86_64`
+   = help: to expect this configuration use `--check-cfg=cfg(target_arch, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:48:5
@@ -106,6 +128,8 @@ LL |     target_endian = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_endian` are: `big`, `little`
+   = help: to expect this configuration use `--check-cfg=cfg(target_endian, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:50:5
@@ -114,6 +138,8 @@ LL |     target_env = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_env` are: ``, `eabihf`, `gnu`, `gnueabihf`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `psx`, `relibc`, `sgx`, `uclibc`
+   = help: to expect this configuration use `--check-cfg=cfg(target_env, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:52:5
@@ -122,6 +148,8 @@ LL |     target_family = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_family` are: `unix`, `wasm`, `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(target_family, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:55:5
@@ -130,6 +158,8 @@ LL |     target_has_atomic = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_has_atomic` are: (none), `128`, `16`, `32`, `64`, `8`, `ptr`
+   = help: to expect this configuration use `--check-cfg=cfg(target_has_atomic, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:57:5
@@ -138,6 +168,8 @@ LL |     target_has_atomic_equal_alignment = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_has_atomic_equal_alignment` are: (none), `128`, `16`, `32`, `64`, `8`, `ptr`
+   = help: to expect this configuration use `--check-cfg=cfg(target_has_atomic_equal_alignment, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:59:5
@@ -146,6 +178,8 @@ LL |     target_has_atomic_load_store = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_has_atomic_load_store` are: (none), `128`, `16`, `32`, `64`, `8`, `ptr`
+   = help: to expect this configuration use `--check-cfg=cfg(target_has_atomic_load_store, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:61:5
@@ -154,6 +188,8 @@ LL |     target_os = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `openbsd`, `psp`, `redox`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`
+   = help: to expect this configuration use `--check-cfg=cfg(target_os, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:63:5
@@ -162,6 +198,8 @@ LL |     target_pointer_width = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_pointer_width` are: `16`, `32`, `64`
+   = help: to expect this configuration use `--check-cfg=cfg(target_pointer_width, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:65:5
@@ -172,6 +210,8 @@ LL |     target_thread_local = "_UNEXPECTED_VALUE",
    |                        help: remove the value
    |
    = note: no expected value for `target_thread_local`
+   = help: to expect this configuration use `--check-cfg=cfg(target_thread_local, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:67:5
@@ -180,6 +220,8 @@ LL |     target_vendor = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: expected values for `target_vendor` are: `apple`, `espressif`, `fortanix`, `ibm`, `kmc`, `nintendo`, `nvidia`, `pc`, `sony`, `sun`, `unikraft`, `unknown`, `uwp`, `win7`, `wrs`
+   = help: to expect this configuration use `--check-cfg=cfg(target_vendor, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:69:5
@@ -190,6 +232,8 @@ LL |     test = "_UNEXPECTED_VALUE",
    |         help: remove the value
    |
    = note: no expected value for `test`
+   = help: to expect this configuration use `--check-cfg=cfg(test, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:71:5
@@ -200,6 +244,8 @@ LL |     unix = "_UNEXPECTED_VALUE",
    |         help: remove the value
    |
    = note: no expected value for `unix`
+   = help: to expect this configuration use `--check-cfg=cfg(unix, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
   --> $DIR/well-known-values.rs:73:5
@@ -210,6 +256,8 @@ LL |     windows = "_UNEXPECTED_VALUE",
    |            help: remove the value
    |
    = note: no expected value for `windows`
+   = help: to expect this configuration use `--check-cfg=cfg(windows, values("_UNEXPECTED_VALUE"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `linuz`
   --> $DIR/well-known-values.rs:79:7
@@ -220,6 +268,8 @@ LL | #[cfg(target_os = "linuz")] // testing that we suggest `linux`
    |                   help: there is a expected value with a similar name: `"linux"`
    |
    = note: expected values for `target_os` are: `aix`, `android`, `cuda`, `dragonfly`, `emscripten`, `espidf`, `freebsd`, `fuchsia`, `haiku`, `hermit`, `horizon`, `hurd`, `illumos`, `ios`, `l4re`, `linux`, `macos`, `netbsd`, `none`, `nto`, `openbsd`, `psp`, `redox`, `solaris`, `solid_asp3`, `teeos`, `tvos`, `uefi`, `unknown`, `vita`, `vxworks`, `wasi`, `watchos`, `windows`, `xous`
+   = help: to expect this configuration use `--check-cfg=cfg(target_os, values("linuz"))`
+   = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: 25 warnings emitted