Stabilize #[cfg(version(...))]

compiler/rustc_attr_data_structures/src/version.rs

@@ -1,4 +1,5 @@
 use std::fmt::{self, Display};
+use std::sync::OnceLock;
 
 use rustc_macros::{
     Decodable, Encodable, HashStable_Generic, PrintAttribute, current_rustc_version,
@@ -16,8 +17,29 @@ pub struct RustcVersion {
 
 impl RustcVersion {
     pub const CURRENT: Self = current_rustc_version!();
+    pub fn current_configurable() -> Self {
+        *CURRENT_CONFIGURABLE.get_or_init(|| {
+            if let Ok(override_var) = std::env::var("RUSTC_OVERRIDE_VERSION_STRING")
+                && let Some(override_) = Self::parse_str(&override_var)
+            {
+                override_
+            } else {
+                Self::CURRENT
+            }
+        })
+    }
+    fn parse_str(value: &str) -> Option<Self> {
+        // Ignore any suffixes such as "-dev" or "-nightly".
+        let mut components = value.split('-').next().unwrap().splitn(3, '.');
+        let major = components.next()?.parse().ok()?;
+        let minor = components.next()?.parse().ok()?;
+        let patch = components.next().unwrap_or("0").parse().ok()?;
+        Some(RustcVersion { major, minor, patch })
+    }
 }
 
+static CURRENT_CONFIGURABLE: OnceLock<RustcVersion> = OnceLock::new();
+
 impl Display for RustcVersion {
     fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(formatter, "{}.{}.{}", self.major, self.minor, self.patch)

compiler/rustc_attr_parsing/src/attributes/cfg.rs

@@ -129,9 +129,9 @@ pub fn eval_condition(
 
             // See https://github.com/rust-lang/rust/issues/64796#issuecomment-640851454 for details
             if sess.psess.assume_incomplete_release {
-                RustcVersion::CURRENT > min_version
+                RustcVersion::current_configurable() > min_version
             } else {
-                RustcVersion::CURRENT >= min_version
+                RustcVersion::current_configurable() >= min_version
             }
         }
         MetaItemKind::List(mis) => {

compiler/rustc_feature/src/accepted.rs

@@ -107,6 +107,8 @@ declare_features! (
     (accepted, cfg_target_feature, "1.27.0", Some(29717)),
     /// Allows `cfg(target_vendor = "...")`.
     (accepted, cfg_target_vendor, "1.33.0", Some(29718)),
+    /// Allow conditional compilation depending on rust version
+    (accepted, cfg_version, "CURRENT_RUSTC_VERSION", Some(64796)),
     /// Allows implementing `Clone` for closures where possible (RFC 2132).
     (accepted, clone_closures, "1.26.0", Some(44490)),
     /// Allows coercing non capturing closures to function pointers.

compiler/rustc_feature/src/builtin_attrs.rs

@@ -33,7 +33,6 @@ const GATED_CFGS: &[GatedCfg] = &[
         Features::cfg_target_has_atomic,
     ),
     (sym::sanitize, sym::cfg_sanitize, Features::cfg_sanitize),
-    (sym::version, sym::cfg_version, Features::cfg_version),
     (sym::relocation_model, sym::cfg_relocation_model, Features::cfg_relocation_model),
     (sym::sanitizer_cfi_generalize_pointers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),
     (sym::sanitizer_cfi_normalize_integers, sym::cfg_sanitizer_cfi, Features::cfg_sanitizer_cfi),

compiler/rustc_feature/src/unstable.rs

@@ -418,8 +418,6 @@ declare_features! (
     (unstable, cfg_target_thread_local, "1.7.0", Some(29594)),
     /// Allows the use of `#[cfg(ub_checks)` to check if UB checks are enabled.
     (unstable, cfg_ub_checks, "1.79.0", Some(123499)),
-    /// Allow conditional compilation depending on rust version
-    (unstable, cfg_version, "1.45.0", Some(64796)),
     /// Allows to use the `#[cfi_encoding = ""]` attribute.
     (unstable, cfi_encoding, "1.71.0", Some(89653)),
     /// Allows `for<...>` on closures and coroutines.

tests/ui/cfg/cfg-version/cfg-version-expand.rs

@@ -0,0 +1,20 @@
+//@ run-pass
+//@ rustc-env:RUSTC_OVERRIDE_VERSION_STRING=1.50.3
+
+#[cfg(version("1.49.0"))]
+const ON_1_49_0: bool = true;
+#[cfg(version("1.50"))]
+const ON_1_50_0: bool = true;
+#[cfg(not(version("1.51")))]
+const ON_1_51_0: bool = false;
+
+fn main() {
+    assert!(ON_1_49_0);
+    assert!(ON_1_50_0);
+    assert!(!ON_1_51_0);
+    assert!(cfg!(version("1.1")));
+    assert!(cfg!(version("1.49")));
+    assert!(!cfg!(version("1.51")));
+    assert!(!cfg!(version("1.52")));
+    assert!(!cfg!(version("1.100")));
+}

tests/ui/feature-gates/feature-gate-cfg-version.rs → tests/ui/cfg/cfg-version/cfg-version.rs

@@ -1,49 +1,35 @@
 #[cfg(version(42))] //~ ERROR: expected a version literal
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn foo() {}
 #[cfg(version(1.20))] //~ ERROR: expected a version literal
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn foo() -> bool { true }
 #[cfg(version("1.44"))]
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn foo() -> bool { true }
 #[cfg(not(version("1.44")))]
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn foo() -> bool { false }
 
 #[cfg(version("1.43", "1.44", "1.45"))] //~ ERROR: expected single version literal
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version(false))] //~ ERROR: expected a version literal
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("foo"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("999"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("-1"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("65536"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("0"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool { true }
 #[cfg(version("1.0"))]
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool { true }
 #[cfg(version("1.65536.2"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() -> bool  { false }
 #[cfg(version("1.20.0-stable"))] //~ WARNING: unknown version literal format
-//~^ ERROR `cfg(version)` is experimental and subject to change
 fn bar() {}
 
 fn main() {
     assert!(foo());
     assert!(bar());
-    assert!(cfg!(version("1.42"))); //~ ERROR `cfg(version)` is experimental and subject to change
+    assert!(cfg!(version("1.42")));
 }

tests/ui/cfg/cfg-version/cfg-version.stderr

@@ -0,0 +1,68 @@
+error: expected a version literal
+  --> $DIR/cfg-version.rs:1:15
+   |
+LL | #[cfg(version(42))]
+   |               ^^
+
+error: expected a version literal
+  --> $DIR/cfg-version.rs:3:15
+   |
+LL | #[cfg(version(1.20))]
+   |               ^^^^
+
+error: expected single version literal
+  --> $DIR/cfg-version.rs:10:7
+   |
+LL | #[cfg(version("1.43", "1.44", "1.45"))]
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: expected a version literal
+  --> $DIR/cfg-version.rs:12:15
+   |
+LL | #[cfg(version(false))]
+   |               ^^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:14:15
+   |
+LL | #[cfg(version("foo"))]
+   |               ^^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:16:15
+   |
+LL | #[cfg(version("999"))]
+   |               ^^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:18:15
+   |
+LL | #[cfg(version("-1"))]
+   |               ^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:20:15
+   |
+LL | #[cfg(version("65536"))]
+   |               ^^^^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:22:15
+   |
+LL | #[cfg(version("0"))]
+   |               ^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:26:15
+   |
+LL | #[cfg(version("1.65536.2"))]
+   |               ^^^^^^^^^^^
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/cfg-version.rs:28:15
+   |
+LL | #[cfg(version("1.20.0-stable"))]
+   |               ^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors; 7 warnings emitted
+