Auto merge of #118924 - Urgau:check-cfg-exclude-well-known-from-diag, r=petrochenkov

bors · bors · commit f1f8687b06a5 · 2024-01-13T02:13:20.000Z
Exclude well known names from showing a suggestion in check-cfg This PR adds an exclusion for well known names from showing in suggestions of check-cfg/`unexpected_cfgs`. Follow-up to #118213 and fixes #118213 (comment). r? `@petrochenkov`
diff --git a/compiler/rustc_lint/src/context/diagnostics.rs b/compiler/rustc_lint/src/context/diagnostics.rs
@@ -356,6 +356,12 @@ pub(super) fn builtin(
                 }
             }
 
+            // We don't want to suggest adding values to well known names
+            // since those are defined by rustc it-self. Users can still
+            // do it if they want, but should not encourage them.
+            let is_cfg_a_well_know_name =
+                sess.parse_sess.check_config.well_known_names.contains(&name);
+
             let inst = if let Some((value, _value_span)) = value {
                 let pre = if is_from_cargo { "\\" } else { "" };
                 format!("cfg({name}, values({pre}\"{value}{pre}\"))")
@@ -368,12 +374,14 @@ pub(super) fn builtin(
                     if let Some((value, _value_span)) = value {
                         db.help(format!("consider adding `{value}` as a feature in `Cargo.toml`"));
                     }
-                } else {
+                } else if !is_cfg_a_well_know_name {
                     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}`"));
+                if !is_cfg_a_well_know_name {
+                    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");
             }
         }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
@@ -1380,6 +1380,8 @@ pub struct CheckCfg {
     pub exhaustive_values: bool,
     /// All the expected values for a config name
     pub expecteds: FxHashMap<Symbol, ExpectedValues<Symbol>>,
+    /// Well known names (only used for diagnostics purposes)
+    pub well_known_names: FxHashSet<Symbol>,
 }
 
 pub enum ExpectedValues<T> {
@@ -1432,9 +1434,10 @@ impl CheckCfg {
         };
 
         macro_rules! ins {
-            ($name:expr, $values:expr) => {
+            ($name:expr, $values:expr) => {{
+                self.well_known_names.insert($name);
                 self.expecteds.entry($name).or_insert_with($values)
-            };
+            }};
         }
 
         // Symbols are inserted in alphabetical order as much as possible.
diff --git a/tests/ui/check-cfg/compact-values.stderr b/tests/ui/check-cfg/compact-values.stderr
@@ -5,7 +5,6 @@ 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
 
diff --git a/tests/ui/check-cfg/exhaustive-names-values.empty_cfg.stderr b/tests/ui/check-cfg/exhaustive-names-values.empty_cfg.stderr
@@ -18,7 +18,6 @@ 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`
diff --git a/tests/ui/check-cfg/exhaustive-names-values.feature.stderr b/tests/ui/check-cfg/exhaustive-names-values.feature.stderr
@@ -18,7 +18,6 @@ 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`
diff --git a/tests/ui/check-cfg/exhaustive-names-values.full.stderr b/tests/ui/check-cfg/exhaustive-names-values.full.stderr
@@ -18,7 +18,6 @@ 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`
diff --git a/tests/ui/check-cfg/exhaustive-values.empty_cfg.stderr b/tests/ui/check-cfg/exhaustive-values.empty_cfg.stderr
@@ -7,7 +7,6 @@ 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
 
diff --git a/tests/ui/check-cfg/exhaustive-values.without_names.stderr b/tests/ui/check-cfg/exhaustive-values.without_names.stderr
@@ -7,7 +7,6 @@ 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
 
diff --git a/tests/ui/check-cfg/no-expected-values.empty.stderr b/tests/ui/check-cfg/no-expected-values.empty.stderr
@@ -20,7 +20,6 @@ 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
diff --git a/tests/ui/check-cfg/no-expected-values.mixed.stderr b/tests/ui/check-cfg/no-expected-values.mixed.stderr
@@ -20,7 +20,6 @@ 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
diff --git a/tests/ui/check-cfg/no-expected-values.simple.stderr b/tests/ui/check-cfg/no-expected-values.simple.stderr
@@ -20,7 +20,6 @@ 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
diff --git a/tests/ui/check-cfg/well-known-values.stderr b/tests/ui/check-cfg/well-known-values.stderr

Original file line number	Diff line number	Diff line change
`@@ -356,6 +356,12 @@ pub(super) fn builtin(`
`356`	`356`	`}`
`357`	`357`	`}`
`358`	`358`
	`359`	`+ // We don't want to suggest adding values to well known names`
	`360`	`+ // since those are defined by rustc it-self. Users can still`
	`361`	`+ // do it if they want, but should not encourage them.`
	`362`	`+ let is_cfg_a_well_know_name =`
	`363`	`+ sess.parse_sess.check_config.well_known_names.contains(&name);`
	`364`	`+`
`359`	`365`	`let inst = if let Some((value, _value_span)) = value {`
`360`	`366`	`let pre = if is_from_cargo { "\\" } else { "" };`
`361`	`367`	`format!("cfg({name}, values({pre}\"{value}{pre}\"))")`
`@@ -368,12 +374,14 @@ pub(super) fn builtin(`
`368`	`374`	`if let Some((value, _value_span)) = value {`
`369`	`375`	db.help(format!("consider adding `{value}` as a feature in `Cargo.toml`"));
`370`	`376`	`}`
`371`		`- } else {`
	`377`	`+ } else if !is_cfg_a_well_know_name {`
`372`	`378`	db.help(format!("consider using a Cargo feature instead or adding `println!(\"cargo:rustc-check-cfg={inst}\");` to the top of a `build.rs`"));
`373`	`379`	`}`
`374`	`380`	`db.note("see <https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#check-cfg> for more information about checking conditional configuration");`
`375`	`381`	`} else {`
`376`		- db.help(format!("to expect this configuration use `--check-cfg={inst}`"));
	`382`	`+ if !is_cfg_a_well_know_name {`
	`383`	+ db.help(format!("to expect this configuration use `--check-cfg={inst}`"));
	`384`	`+ }`
`377`	`385`	`db.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");`
`378`	`386`	`}`
`379`	`387`	`}`
Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,6 @@ LL \| #[cfg(target(os = "linux", pointer_width = "X"))]`
`5`	`5`	`\| ^^^^^^^^^^^^^^^^^^^`
`6`	`6`	`\|`
`7`	`7`	= note: expected values for `target_pointer_width` are: `16`, `32`, `64`
`8`		- = help: to expect this configuration use `--check-cfg=cfg(target_pointer_width, values("X"))`
`9`	`8`	`= note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration`
`10`	`9`	= note: `#[warn(unexpected_cfgs)]` on by default
`11`	`10`
Original file line number	Diff line number	Diff line change
`@@ -18,7 +18,6 @@ LL \| #[cfg(test = "value")]`
`18`	`18`	`\| help: remove the value`
`19`	`19`	`\|`
`20`	`20`	= note: no expected value for `test`
`21`		- = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
`22`	`21`	`= note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration`
`23`	`22`
`24`	`23`	warning: unexpected `cfg` condition name: `feature`
Original file line number	Diff line number	Diff line change
`@@ -7,7 +7,6 @@ LL \| #[cfg(test = "value")]`
`7`	`7`	`\| help: remove the value`
`8`	`8`	`\|`
`9`	`9`	= note: no expected value for `test`
`10`		- = help: to expect this configuration use `--check-cfg=cfg(test, values("value"))`
`11`	`10`	`= note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration`
`12`	`11`	= note: `#[warn(unexpected_cfgs)]` on by default
`13`	`12`
Original file line number	Diff line number	Diff line change
`@@ -20,7 +20,6 @@ LL \| #[cfg(test = "foo")]`
`20`	`20`	`\| help: remove the value`
`21`	`21`	`\|`
`22`	`22`	= note: no expected value for `test`
`23`		- = help: to expect this configuration use `--check-cfg=cfg(test, values("foo"))`
`24`	`23`	`= note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration`
`25`	`24`
`26`	`25`	`warning: 2 warnings emitted`