Add has_cfg_version cfg

Author: est31

compiler/rustc_lint/messages.ftl

@@ -810,9 +810,10 @@ lint_undropped_manually_drops = calls to `std::mem::drop` with `std::mem::Manual
     .suggestion = use `std::mem::ManuallyDrop::into_inner` to get the inner value
 
 lint_unexpected_builtin_cfg = unexpected `--cfg {$cfg}` flag
-    .controlled_by = config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`
     .incoherent = manually setting a built-in cfg can and does create incoherent behaviors
 
+lint_unexpected_builtin_cfg_controlled_by = config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`
+
 lint_unexpected_cfg_add_build_rs_println = or consider adding `{$build_rs_println}` to the top of the `build.rs`
 lint_unexpected_cfg_add_cargo_feature = consider using a Cargo feature instead
 lint_unexpected_cfg_add_cargo_toml_lint_cfg = or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:{$cargo_toml_lint_cfg}

compiler/rustc_lint/src/early/diagnostics.rs

@@ -448,7 +448,13 @@ pub(super) fn decorate_lint(
             lints::OutOfScopeMacroCalls { span, path, location }.decorate_lint(diag)
         }
         BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by } => {
-            lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
+            lints::UnexpectedBuiltinCfg {
+                cfg,
+                cfg_name,
+                controlled_by: controlled_by
+                    .map(|controlled_by| lints::ControlledBy { controlled_by }),
+            }
+            .decorate_lint(diag)
         }
         BuiltinLintDiag::ElidedNamedLifetimes { elided: (span, kind), resolution } => {
             match resolution {

compiler/rustc_lint/src/lints.rs

@@ -2498,11 +2498,17 @@ pub(crate) mod unexpected_cfg_value {
 
 #[derive(LintDiagnostic)]
 #[diag(lint_unexpected_builtin_cfg)]
-#[note(lint_controlled_by)]
 #[note(lint_incoherent)]
 pub(crate) struct UnexpectedBuiltinCfg {
     pub(crate) cfg: String,
     pub(crate) cfg_name: Symbol,
+    #[subdiagnostic]
+    pub(crate) controlled_by: Option<ControlledBy>,
+}
+
+#[derive(Subdiagnostic)]
+#[note(lint_unexpected_builtin_cfg)]
+pub(crate) struct ControlledBy {
     pub(crate) controlled_by: &'static str,
 }
 

compiler/rustc_lint_defs/src/lib.rs

@@ -827,7 +827,7 @@ pub enum BuiltinLintDiag {
     UnexpectedBuiltinCfg {
         cfg: String,
         cfg_name: Symbol,
-        controlled_by: &'static str,
+        controlled_by: Option<&'static str>,
     },
 }
 

compiler/rustc_session/src/config/cfg.rs

@@ -88,7 +88,7 @@ impl<'a, T: Eq + Hash + Copy + 'a> Extend<&'a T> for ExpectedValues<T> {
 
 /// Disallow builtin cfgs from the CLI.
 pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) {
-    let disallow = |cfg: &(Symbol, Option<Symbol>), controlled_by| {
+    let disallow_controlled_by = |cfg: &(Symbol, Option<Symbol>), controlled_by| {
         let cfg_name = cfg.0;
         let cfg = if let Some(value) = cfg.1 {
             format!(r#"{}="{}""#, cfg_name, value)
@@ -102,6 +102,9 @@ pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) {
             BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by },
         )
     };
+    let disallow = |cfg: &(Symbol, Option<Symbol>), controlled_by| {
+        disallow_controlled_by(cfg, Some(controlled_by));
+    };
 
     // We want to restrict setting builtin cfgs that will produce incoherent behavior
     // between the cfg and the rustc cli flag that sets it.
@@ -147,6 +150,7 @@ pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) {
             | (sym::target_has_reliable_f128, None | Some(_))
             | (sym::target_has_reliable_f128_math, None | Some(_))
             | (sym::target_thread_local, None) => disallow(cfg, "--target"),
+            (sym::has_cfg_version, None) => disallow_controlled_by(cfg, None),
             (sym::fmt_debug, None | Some(_)) => disallow(cfg, "-Z fmt-debug"),
             (sym::emscripten_wasm_eh, None | Some(_)) => disallow(cfg, "-Z emscripten_wasm_eh"),
             _ => {}
@@ -310,6 +314,8 @@ pub(crate) fn default_configuration(sess: &Session) -> Cfg {
         ins_none!(sym::contract_checks);
     }
 
+    ins_none!(sym::has_cfg_version);
+
     ret
 }
 
@@ -472,6 +478,8 @@ impl CheckCfg {
         ins!(sym::ub_checks, no_values);
         ins!(sym::contract_checks, no_values);
 
+        ins!(sym::has_cfg_version, no_values);
+
         ins!(sym::unix, no_values);
         ins!(sym::windows, no_values);
     }

compiler/rustc_span/src/symbol.rs

@@ -1089,6 +1089,7 @@ symbols! {
         guard_patterns,
         half_open_range_patterns,
         half_open_range_patterns_in_slices,
+        has_cfg_version,
         hash,
         hashmap_contains_key,
         hashmap_drain_ty,

tests/ui/cfg/disallowed-cli-cfgs.rs

@@ -9,6 +9,7 @@
 //@ revisions: fmt_debug_
 //@ revisions: emscripten_wasm_eh_
 //@ revisions: reliable_f16_ reliable_f16_math_ reliable_f128_ reliable_f128_math_
+//@ revisions: has_cfg_version_
 
 //@ [overflow_checks_]compile-flags: --cfg overflow_checks
 //@ [debug_assertions_]compile-flags: --cfg debug_assertions
@@ -40,6 +41,7 @@
 //@ [reliable_f16_math_]compile-flags: --cfg target_has_reliable_f16_math
 //@ [reliable_f128_]compile-flags: --cfg target_has_reliable_f128
 //@ [reliable_f128_math_]compile-flags: --cfg target_has_reliable_f128_math
+//@ [has_cfg_version_]compile-flags: --cfg has_cfg_version
 
 fn main() {}