Rollup merge of #120435 - chenyukang:yukang-fix-120427-cfg-name, r=Urgau,Nilstrieb

Suggest name value cfg when only value is used for check-cfg

Fixes #120427
r? `````````````@Nilstrieb`````````````

compiler/rustc_lint/src/context/diagnostics.rs

@@ -188,6 +188,23 @@ pub(super) fn builtin(
             #[allow(rustc::potential_query_instability)]
             let possibilities: Vec<Symbol> =
                 sess.parse_sess.check_config.expecteds.keys().copied().collect();
+
+            let mut names_possibilities: Vec<_> = if value.is_none() {
+                // We later sort and display all the possibilities, so the order here does not matter.
+                #[allow(rustc::potential_query_instability)]
+                sess.parse_sess
+                    .check_config
+                    .expecteds
+                    .iter()
+                    .filter_map(|(k, v)| match v {
+                        ExpectedValues::Some(v) if v.contains(&Some(name)) => Some(k),
+                        _ => None,
+                    })
+                    .collect()
+            } else {
+                Vec::new()
+            };
+
             let is_from_cargo = std::env::var_os("CARGO").is_some();
             let mut is_feature_cfg = name == sym::feature;
 
@@ -262,7 +279,19 @@ pub(super) fn builtin(
                 }
 
                 is_feature_cfg |= best_match == sym::feature;
-            } else if !possibilities.is_empty() {
+            } else {
+                if !names_possibilities.is_empty() && names_possibilities.len() <= 3 {
+                    names_possibilities.sort();
+                    for cfg_name in names_possibilities.iter() {
+                        db.span_suggestion(
+                            name_span,
+                            "found config with similar value",
+                            format!("{cfg_name} = \"{name}\""),
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+                if !possibilities.is_empty() {
                     let mut possibilities =
                         possibilities.iter().map(Symbol::as_str).collect::<Vec<_>>();
                     possibilities.sort();
@@ -274,6 +303,7 @@ pub(super) fn builtin(
                     // 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 { "" };

tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.rs

@@ -0,0 +1,12 @@
+// #120427
+// 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)]
+//~^ WARNING unexpected `cfg` condition name: `value`
+fn x() {}
+
+fn main() {}

tests/ui/check-cfg/cfg-value-for-cfg-name-duplicate.stderr

@@ -0,0 +1,13 @@
+warning: unexpected `cfg` condition name: `value`
+  --> $DIR/cfg-value-for-cfg-name-duplicate.rs:8:7
+   |
+LL | #[cfg(value)]
+   |       ^^^^^
+   |
+   = help: expected names are: `bar`, `bee`, `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`, `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: `#[warn(unexpected_cfgs)]` on by default
+
+warning: 1 warning emitted
+

tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.rs

@@ -0,0 +1,12 @@
+// #120427
+// 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)]
+//~^ WARNING unexpected `cfg` condition name: `my_value`
+fn x() {}
+
+fn main() {}

tests/ui/check-cfg/cfg-value-for-cfg-name-multiple.stderr

@@ -0,0 +1,21 @@
+warning: unexpected `cfg` condition name: `my_value`
+  --> $DIR/cfg-value-for-cfg-name-multiple.rs:8:7
+   |
+LL | #[cfg(my_value)]
+   |       ^^^^^^^^
+   |
+   = help: expected names are: `bar`, `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`, `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: `#[warn(unexpected_cfgs)]` on by default
+help: found config with similar value
+   |
+LL | #[cfg(foo = "my_value")]
+   |       ~~~~~~~~~~~~~~~~
+help: found config with similar value
+   |
+LL | #[cfg(bar = "my_value")]
+   |       ~~~~~~~~~~~~~~~~
+
+warning: 1 warning emitted
+

tests/ui/check-cfg/cfg-value-for-cfg-name.rs

@@ -0,0 +1,18 @@
+// #120427
+// This test checks that when a single cfg has a value for user's specified name
+// 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)]
+//~^ WARNING unexpected `cfg` condition name: `linux`
+fn x() {}
+
+// will not suggest if the cfg has a value
+#[cfg(linux = "os-name")]
+//~^ WARNING unexpected `cfg` condition name: `linux`
+fn y() {}
+
+fn main() {}

tests/ui/check-cfg/cfg-value-for-cfg-name.stderr

@@ -0,0 +1,22 @@
+warning: unexpected `cfg` condition name: `linux`
+  --> $DIR/cfg-value-for-cfg-name.rs:9:7
+   |
+LL | #[cfg(linux)]
+   |       ^^^^^ help: found config with similar value: `target_os = "linux"`
+   |
+   = 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(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
+
+warning: unexpected `cfg` condition name: `linux`
+  --> $DIR/cfg-value-for-cfg-name.rs:14:7
+   |
+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
+
+warning: 2 warnings emitted
+