Auto merge of #118071 - Urgau:check-cfg-cargo-feature, r=petrochenkov

Remove `feature` from the list of well known check-cfg name

This PR removes `feature` from the list of well known check-cfg.

This is done for multiple reasons:
 - Cargo is the source of truth, rustc shouldn't have any knowledge of it
 - It creates a conflict between Cargo and rustc when there are no features defined.
   In this case Cargo won't pass any `--check-cfg` for `feature` since no feature will ever be passed, but rustc by having in it's list adds a implicit `cfg(feature, values(any()))` which is completely wrong. Having any cfg `feature` is unexpected not allow any `feature` value.

While doing this, I took the opportunity to specialise the diagnostic a bit for the case above.

r? `@petrochenkov`

compiler/rustc_lint/src/context.rs

@@ -739,6 +739,8 @@ 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`");
                     } else if !possibilities.is_empty() {
                         let mut possibilities = possibilities.iter()
                             .map(Symbol::as_str)

compiler/rustc_session/src/config.rs

@@ -1443,9 +1443,8 @@ impl CheckCfg {
         let relocation_model_values = RelocModel::all();
 
         // Unknown possible values:
-        //  - `feature`
         //  - `target_feature`
-        for name in [sym::feature, sym::target_feature] {
+        for name in [sym::target_feature] {
             self.expecteds.entry(name).or_insert(ExpectedValues::Any);
         }
 

src/bootstrap/src/bin/rustc.rs

@@ -114,7 +114,7 @@ fn main() {
         {
             cmd.arg("-Ztls-model=initial-exec");
         }
-    } else {
+    } else if std::env::var("MIRI").is_err() {
         // Find any host flags that were passed by bootstrap.
         // The flags are stored in a RUSTC_HOST_FLAGS variable, separated by spaces.
         if let Ok(flags) = std::env::var("RUSTC_HOST_FLAGS") {

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `FALSE`
 LL | #[cfg(FALSE)]
    |       ^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

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

@@ -0,0 +1,14 @@
+// This test checks that when no features are passed by Cargo we
+// suggest adding some in the Cargo.toml instead of vomitting a
+// list of all the expected names
+//
+// check-pass
+// rustc-env:CARGO=/usr/bin/cargo
+// compile-flags: --check-cfg=cfg() -Z unstable-options
+// error-pattern:Cargo.toml
+
+#[cfg(feature = "serde")]
+//~^ WARNING unexpected `cfg` condition name
+fn ser() {}
+
+fn main() {}

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

@@ -0,0 +1,11 @@
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/cargo-feature.rs:10:7
+   |
+LL | #[cfg(feature = "serde")]
+   |       ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider defining some features in `Cargo.toml`
+   = note: `#[warn(unexpected_cfgs)]` on by default
+
+warning: 1 warning emitted
+

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `target_architecture`
 LL | #[cfg(target(os = "linux", architecture = "arm"))]
    |                            ^^^^^^^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `unknown_key`
 LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `value`
@@ -17,5 +17,17 @@ LL | #[cfg(test = "value")]
    |
    = note: no expected value for `test`
 
-warning: 2 warnings emitted
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/exhaustive-names-values.rs:19:7
+   |
+LL | #[cfg(feature = "unk")]
+   |       ^^^^^^^^^^^^^^^
+
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/exhaustive-names-values.rs:26:7
+   |
+LL | #[cfg(feature = "std")]
+   |       ^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
 

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `unknown_key`
 LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: unexpected `cfg` condition value: `value`
@@ -17,5 +17,17 @@ LL | #[cfg(test = "value")]
    |
    = note: no expected value for `test`
 
-warning: 2 warnings emitted
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/exhaustive-names-values.rs:19:7
+   |
+LL | #[cfg(feature = "unk")]
+   |       ^^^^^^^^^^^^^^^
+
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/exhaustive-names-values.rs:26:7
+   |
+LL | #[cfg(feature = "std")]
+   |       ^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
 

tests/ui/check-cfg/exhaustive-names-values.rs

@@ -17,11 +17,15 @@ pub fn f() {}
 pub fn f() {}
 
 #[cfg(feature = "unk")]
-//[feature]~^ WARNING unexpected `cfg` condition value
-//[full]~^^ WARNING unexpected `cfg` condition value
+//[empty_names_values]~^ WARNING unexpected `cfg` condition name
+//[empty_cfg]~^^ WARNING unexpected `cfg` condition name
+//[feature]~^^^ WARNING unexpected `cfg` condition value
+//[full]~^^^^ WARNING unexpected `cfg` condition value
 pub fn feat() {}
 
 #[cfg(feature = "std")]
+//[empty_names_values]~^ WARNING unexpected `cfg` condition name
+//[empty_cfg]~^^ WARNING unexpected `cfg` condition name
 pub fn feat() {}
 
 #[cfg(windows)]

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `unknown_key`
 LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

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

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `unknown_key`
 LL | #[cfg(unknown_key = "value")]
    |       ^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/stmt-no-ice.stderr

@@ -4,7 +4,7 @@ warning: unexpected `cfg` condition name: `crossbeam_loom`
 LL |     #[cfg(crossbeam_loom)]
    |           ^^^^^^^^^^^^^^
    |
-   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `feature`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
    = note: `#[warn(unexpected_cfgs)]` on by default
 
 warning: 1 warning emitted

tests/ui/check-cfg/well-known-names.rs

@@ -15,6 +15,7 @@ fn target_os() {}
 fn feature_misspell() {}
 
 #[cfg(feature = "foo")]
+//~^ WARNING unexpected `cfg` condition name
 fn feature() {}
 
 #[cfg(uniw)]

tests/ui/check-cfg/well-known-names.stderr

@@ -14,15 +14,21 @@ warning: unexpected `cfg` condition name: `features`
   --> $DIR/well-known-names.rs:13:7
    |
 LL | #[cfg(features = "foo")]
-   |       --------^^^^^^^^
-   |       |
-   |       help: there is a config with a similar name: `feature`
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = help: expected names are: `debug_assertions`, `doc`, `doctest`, `miri`, `overflow_checks`, `panic`, `proc_macro`, `relocation_model`, `sanitize`, `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`
+
+warning: unexpected `cfg` condition name: `feature`
+  --> $DIR/well-known-names.rs:17:7
+   |
+LL | #[cfg(feature = "foo")]
+   |       ^^^^^^^^^^^^^^^
 
 warning: unexpected `cfg` condition name: `uniw`
-  --> $DIR/well-known-names.rs:20:7
+  --> $DIR/well-known-names.rs:21:7
    |
 LL | #[cfg(uniw)]
    |       ^^^^ help: there is a config with a similar name: `unix`
 
-warning: 3 warnings emitted
+warning: 4 warnings emitted