Rollup merge of #117256 - dtolnay:currentversion, r=compiler-errors

Parse rustc version at compile time

This PR eliminates a couple awkward codepaths where it was not clear how the compiler should proceed if its own version number is incomprehensible.

https://github.com/rust-lang/rust/blob/dab715641e96a61a534587fda9de1128b75b34dc/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs#L385

https://github.com/rust-lang/rust/blob/dab715641e96a61a534587fda9de1128b75b34dc/compiler/rustc_attr/src/builtin.rs#L630

We can guarantee that every compiled rustc comes with a working version number, so the ICE codepaths above shouldn't need to be written.

2 files changed, 22 insertions, 0 deletions

diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 7da0bcf01bf..17ac3e991c5 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -43,6 +43,9 @@ pub mod output;
 
 pub use getopts;
 
+mod version;
+pub use version::RustcVersion;
+
 fluent_messages! { "../messages.ftl" }
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
diff --git a/compiler/rustc_session/src/version.rs b/compiler/rustc_session/src/version.rs
new file mode 100644
index 00000000000..1ad8620bfba
--- /dev/null
+++ b/compiler/rustc_session/src/version.rs
@@ -0,0 +1,19 @@
+use std::fmt::{self, Display};
+
+#[derive(Encodable, Decodable, Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(HashStable_Generic)]
+pub struct RustcVersion {
+    pub major: u16,
+    pub minor: u16,
+    pub patch: u16,
+}
+
+impl RustcVersion {
+    pub const CURRENT: Self = current_rustc_version!(env!("CFG_RELEASE"));
+}
+
+impl Display for RustcVersion {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(formatter, "{}.{}.{}", self.major, self.minor, self.patch)
+    }
+}