Introduce CARGO_PKG_EDITION env var

Solves #14872

Author: nyurik

Cargo.lock

@@ -51,6 +51,7 @@ fn smoke_test_inputs() {
     dbg!(cargo_manifest_links());
     dbg!(cargo_pkg_authors());
     dbg!(cargo_pkg_description());
+    dbg!(cargo_pkg_edition());
     dbg!(cargo_pkg_homepage());
     dbg!(cargo_pkg_license());
     dbg!(cargo_pkg_license_file());

crates/build-rs-test-lib/build.rs

@@ -1,6 +1,6 @@
 [package]
 name = "build-rs"
-version = "0.3.2"
+version = "0.3.3"
 rust-version.workspace = true
 edition.workspace = true
 license.workspace = true

crates/build-rs/Cargo.toml

@@ -580,6 +580,12 @@ pub fn cargo_pkg_description() -> Option<String> {
     to_opt(var_or_panic("CARGO_PKG_DESCRIPTION")).map(to_string)
 }
 
+/// The Rust language edition from the manifest of your package.
+#[track_caller]
+pub fn cargo_pkg_edition() -> Option<String> {
+    to_opt(var_or_panic("CARGO_PKG_EDITION")).map(to_string)
+}
+
 /// The home page from the manifest of your package.
 #[track_caller]
 pub fn cargo_pkg_homepage() -> Option<String> {

crates/build-rs/src/input.rs

@@ -362,6 +362,7 @@ impl<'gctx> Compilation<'gctx> {
         // in BuildContext::target_metadata()
         cmd.env("CARGO_MANIFEST_DIR", pkg.root())
             .env("CARGO_MANIFEST_PATH", pkg.manifest_path())
+            .env("CARGO_PKG_EDITION", pkg.edition().to_string())
             .env("CARGO_PKG_VERSION_MAJOR", &pkg.version().major.to_string())
             .env("CARGO_PKG_VERSION_MINOR", &pkg.version().minor.to_string())
             .env("CARGO_PKG_VERSION_PATCH", &pkg.version().patch.to_string())

src/cargo/core/compiler/compilation.rs

@@ -22,8 +22,8 @@ use crate::core::dependency::DepKind;
 use crate::core::resolver::features::ForceAllTargets;
 use crate::core::resolver::{HasDevUnits, Resolve};
 use crate::core::{
-    CliUnstable, Dependency, Features, Manifest, PackageId, PackageIdSpec, SerializedDependency,
-    SourceId, Target,
+    CliUnstable, Dependency, Edition, Features, Manifest, PackageId, PackageIdSpec,
+    SerializedDependency, SourceId, Target,
 };
 use crate::core::{Summary, Workspace};
 use crate::sources::source::{MaybePackage, SourceMap};
@@ -169,6 +169,10 @@ impl Package {
     pub fn proc_macro(&self) -> bool {
         self.targets().iter().any(|target| target.proc_macro())
     }
+    /// Gets the package's language edition
+    pub fn edition(&self) -> Edition {
+        self.manifest().edition()
+    }
     /// Gets the package's minimum Rust version.
     pub fn rust_version(&self) -> Option<&RustVersion> {
         self.manifest().rust_version()

src/cargo/core/package.rs

@@ -245,6 +245,7 @@ corresponding environment variable is set to the empty string, `""`.
 * `CARGO_PKG_REPOSITORY` --- The repository from the manifest of your package.
 * `CARGO_PKG_LICENSE` --- The license from the manifest of your package.
 * `CARGO_PKG_LICENSE_FILE` --- The license file from the manifest of your package.
+* `CARGO_PKG_EDITION` --- The Rust language edition from the manifest of your package.
 * `CARGO_PKG_RUST_VERSION` --- The Rust version from the manifest of your package.
   Note that this is the minimum Rust version supported by the package, not the
   current Rust version.

src/doc/src/reference/environment-variables.md

@@ -1629,6 +1629,7 @@ fn crate_env_vars() {
                 static LICENSE: &'static str = env!("CARGO_PKG_LICENSE");
                 static LICENSE_FILE: &'static str = env!("CARGO_PKG_LICENSE_FILE");
                 static DESCRIPTION: &'static str = env!("CARGO_PKG_DESCRIPTION");
+                static EDITION: &'static str = env!("CARGO_PKG_EDITION");
                 static RUST_VERSION: &'static str = env!("CARGO_PKG_RUST_VERSION");
                 static README: &'static str = env!("CARGO_PKG_README");
                 static BIN_NAME: &'static str = env!("CARGO_BIN_NAME");