Stabilize edition key and add cargo new --edition

This commit stabilizes the `edition` key in `Cargo.toml`, both in the
`[package]` section and inside subtargets. Additionally the `cargo new` and
`cargo init` subcommands have been enhanced with a `--edition` flag to allow
explicitly specifying the edition to be generated.

This commit does not yet change the default edition that's generated.

Closes #5980

Author: alexcrichton

src/bin/cargo/command_prelude.rs

@@ -147,8 +147,14 @@ pub trait AppExt: Sized {
                  a global configuration.",
             ).value_name("VCS")
                 .possible_values(&["git", "hg", "pijul", "fossil", "none"]),
-        )._arg(opt("bin", "Use a binary (application) template [default]"))
+        )
+            ._arg(opt("bin", "Use a binary (application) template [default]"))
             ._arg(opt("lib", "Use a library template"))
+            ._arg(
+                opt("edition", "Edition to set for the crate generated")
+                    .possible_values(&["2015", "2018"])
+                    .value_name("YEAR")
+            )
             ._arg(
                 opt(
                     "name",
@@ -339,6 +345,7 @@ pub trait ArgMatchesExt {
             self._is_present("lib"),
             self.value_of_path("path", config).unwrap(),
             self._value_of("name").map(|s| s.to_string()),
+            self._value_of("edition").map(|s| s.to_string()),
         )
     }
 

src/cargo/core/compiler/compilation.rs

@@ -6,7 +6,7 @@ use std::path::PathBuf;
 use semver::Version;
 use lazycell::LazyCell;
 
-use core::{Feature, Package, PackageId, Target, TargetKind};
+use core::{Edition, Package, PackageId, Target, TargetKind};
 use util::{self, join_paths, process, CargoResult, Config, ProcessBuilder};
 use super::BuildContext;
 
@@ -123,8 +123,7 @@ impl<'cfg> Compilation<'cfg> {
     /// See `process`.
     pub fn rustc_process(&self, pkg: &Package, target: &Target) -> CargoResult<ProcessBuilder> {
         let mut p = self.fill_env(self.rustc_process.clone(), pkg, true)?;
-        let manifest = pkg.manifest();
-        if manifest.features().is_enabled(Feature::edition()) {
+        if target.edition() != Edition::Edition2015 {
             p.arg(format!("--edition={}", target.edition()));
         }
         Ok(p)
@@ -133,8 +132,7 @@ impl<'cfg> Compilation<'cfg> {
     /// See `process`.
     pub fn rustdoc_process(&self, pkg: &Package, target: &Target) -> CargoResult<ProcessBuilder> {
         let mut p = self.fill_env(process(&*self.config.rustdoc()?), pkg, false)?;
-        let manifest = pkg.manifest();
-        if manifest.features().is_enabled(Feature::edition()) {
+        if target.edition() != Edition::Edition2015 {
             p.arg("-Zunstable-options");
             p.arg(format!("--edition={}", target.edition()));
         }

src/cargo/core/features.rs

@@ -85,6 +85,7 @@ impl FromStr for Edition {
     }
 }
 
+#[derive(PartialEq)]
 enum Status {
     Stable,
     Unstable,
@@ -106,7 +107,7 @@ macro_rules! features {
             $(
                 pub fn $feature() -> &'static Feature {
                     fn get(features: &Features) -> bool {
-                        features.$feature
+                        stab!($stab) == Status::Stable || features.$feature
                     }
                     static FEAT: Feature = Feature {
                         name: stringify!($feature),
@@ -173,7 +174,7 @@ features! {
         [unstable] alternative_registries: bool,
 
         // Using editions
-        [unstable] edition: bool,
+        [stable] edition: bool,
 
         // Renaming a package in the manifest via the `package` key
         [unstable] rename_dependency: bool,

src/cargo/ops/cargo_new.rs

@@ -30,6 +30,7 @@ pub struct NewOptions {
     /// Absolute path to the directory for the new project
     pub path: PathBuf,
     pub name: Option<String>,
+    pub edition: Option<String>,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -65,6 +66,7 @@ struct MkOptions<'a> {
     name: &'a str,
     source_files: Vec<SourceFileInformation>,
     bin: bool,
+    edition: Option<&'a str>,
 }
 
 impl NewOptions {
@@ -74,6 +76,7 @@ impl NewOptions {
         lib: bool,
         path: PathBuf,
         name: Option<String>,
+        edition: Option<String>,
     ) -> CargoResult<NewOptions> {
         let kind = match (bin, lib) {
             (true, true) => bail!("can't specify both lib and binary outputs"),
@@ -87,6 +90,7 @@ impl NewOptions {
             kind,
             path,
             name,
+            edition,
         };
         Ok(opts)
     }
@@ -321,6 +325,7 @@ pub fn new(opts: &NewOptions, config: &Config) -> CargoResult<()> {
         name,
         source_files: vec![plan_new_source_file(opts.kind.is_bin(), name.to_string())],
         bin: opts.kind.is_bin(),
+        edition: opts.edition.as_ref().map(|s| &**s),
     };
 
     mk(config, &mkopts).chain_err(|| {
@@ -397,6 +402,7 @@ pub fn init(opts: &NewOptions, config: &Config) -> CargoResult<()> {
         name,
         bin: src_paths_types.iter().any(|x| x.bin),
         source_files: src_paths_types,
+        edition: opts.edition.as_ref().map(|s| &**s),
     };
 
     mk(config, &mkopts).chain_err(|| {
@@ -529,12 +535,19 @@ path = {}
             r#"[package]
 name = "{}"
 version = "0.1.0"
-authors = [{}]
+authors = [{}]{}
 
 [dependencies]
 {}"#,
             name,
             toml::Value::String(author),
+            match opts.edition {
+                Some(edition) => {
+                    let edition = toml::Value::String(edition.to_string());
+                    format!("\nedition = {}", edition)
+                }
+                None => String::new(),
+            },
             cargotoml_path_specifier
         ).as_bytes(),
     )?;

src/doc/src/reference/manifest.md

@@ -31,6 +31,24 @@ Versioning](http://semver.org/), so make sure you follow some basic rules:
   traits, fields, types, functions, methods or anything else.
 * Use version numbers with three numeric parts such as 1.0.0 rather than 1.0.
 
+#### The `edition` field (optional)
+
+You can opt in to a specific Rust Edition for your package with the
+`edition` key in `Cargo.toml`.  If you don't specify the edition, it will
+default to 2015.
+
+```toml
+[package]
+# ...
+edition = '2018'
+```
+
+The `edition` key affects which edition your package is compiled with. Cargo
+will always generate projects via `cargo new` with the `edition` key set to the
+latest edition. Setting the `edition` key in `[package]` will affect all
+targets/crates in the package, including test suites, benchmarks, binaries,
+examples, etc.
+
 #### The `build` field (optional)
 
 This field specifies a file in the project root which is a [build script][1] for
@@ -714,6 +732,12 @@ proc-macro = false
 # stops it from generating a test harness. This is useful when the binary being
 # built manages the test runner itself.
 harness = true
+
+# If set then a target can be configured to use a different edition than the
+# `[package]` is configured to use, perhaps only compiling a library with the
+# 2018 edition or only compiling one unit test with the 2015 edition. By default
+# all targets are compiled with the edition specified in `[package]`.
+edition = '2015'
 ```
 
 The `[package]` also includes the optional `autobins`, `autoexamples`,

src/doc/src/reference/unstable.md

@@ -199,30 +199,6 @@ cargo +nightly build --out-dir=out -Z unstable-options
 ```
 
 
-### Edition
-* Tracking Issue: [rust-lang/rust#44581](https://github.com/rust-lang/rust/issues/44581)
-* RFC: [#2052](https://github.com/rust-lang/rfcs/blob/master/text/2052-epochs.md)
-
-You can opt in to a specific Rust Edition for your package with the `edition`
-key in `Cargo.toml`.  If you don't specify the edition, it will default to
-2015.  You need to include the appropriate `cargo-features`.
-
-You can also specify `edition` on a per-target level, where it will otherwise
-default to the package `edition`.
-
-```toml
-cargo-features = ["edition"]
-
-[package]
-...
-edition = "2018"
-
-[[bin]]
-...
-edition = "2015"
-```
-
-
 ### Profile Overrides
 * Tracking Issue: [rust-lang/rust#48683](https://github.com/rust-lang/rust/issues/48683)
 * RFC: [#2282](https://github.com/rust-lang/rfcs/blob/master/text/2282-profile-dependencies.md)

tests/testsuite/bench.rs

@@ -549,45 +549,42 @@ fn bench_autodiscover_2015() {
         .file(
             "Cargo.toml",
             r#"
-            cargo-features = ["edition"]
-
-            [project]
-            name = "foo"
-            version = "0.0.1"
-            authors = []
-            edition = "2015"
-
-            [[bench]]
-            name = "bench_magic"
-            required-features = ["magic"]
-        "#,
+                [project]
+                name = "foo"
+                version = "0.0.1"
+                authors = []
+                edition = "2015"
+
+                [[bench]]
+                name = "bench_magic"
+                required-features = ["magic"]
+            "#,
         ).file("src/lib.rs", "")
         .file(
             "benches/bench_basic.rs",
             r#"
-            #![feature(test)]
-            #[allow(unused_extern_crates)]
-            extern crate foo;
-            extern crate test;
+                #![feature(test)]
+                #[allow(unused_extern_crates)]
+                extern crate foo;
+                extern crate test;
 
-            #[bench]
-            fn bench_basic(_b: &mut test::Bencher) {}
-        "#,
+                #[bench]
+                fn bench_basic(_b: &mut test::Bencher) {}
+            "#,
         ).file(
             "benches/bench_magic.rs",
             r#"
-            #![feature(test)]
-            #[allow(unused_extern_crates)]
-            extern crate foo;
-            extern crate test;
+                #![feature(test)]
+                #[allow(unused_extern_crates)]
+                extern crate foo;
+                extern crate test;
 
-            #[bench]
-            fn bench_magic(_b: &mut test::Bencher) {}
-        "#,
+                #[bench]
+                fn bench_magic(_b: &mut test::Bencher) {}
+            "#,
         ).build();
 
     p.cargo("bench bench_basic")
-        .masquerade_as_nightly_cargo()
         .with_stderr(
             "warning: \
 An explicit [[bench]] section is specified in Cargo.toml which currently

tests/testsuite/build.rs

@@ -3928,19 +3928,17 @@ fn target_edition() {
         .file(
             "Cargo.toml",
             r#"
-            cargo-features = ["edition"]
-            [package]
-            name = "foo"
-            version = "0.0.1"
+                [package]
+                name = "foo"
+                version = "0.0.1"
 
-            [lib]
-            edition = "2018"
-        "#,
+                [lib]
+                edition = "2018"
+            "#,
         ).file("src/lib.rs", "")
         .build();
 
     p.cargo("build -v")
-        .masquerade_as_nightly_cargo()
         .with_stderr_contains(
             "\
 [COMPILING] foo v0.0.1 ([..])
@@ -3955,62 +3953,26 @@ fn target_edition_override() {
         .file(
             "Cargo.toml",
             r#"
-            cargo-features = ["edition"]
-            [package]
-            name = "foo"
-            version = "0.0.1"
-            authors = []
-            edition = "2018"
-
-            [lib]
-            edition = "2015"
-        "#,
-        ).file("src/lib.rs", "")
-        .build();
-
-    p.cargo("build -v")
-        .masquerade_as_nightly_cargo()
-        .with_stderr_contains(
-            "\
-[COMPILING] foo v0.0.1 ([..])
-[RUNNING] `rustc [..]--edition=2015 [..]
-",
-        ).run();
-}
-
-#[test]
-fn target_edition_feature_gated() {
-    let p = project()
-        .file(
-            "Cargo.toml",
-            r#"
-            [package]
-            name = "foo"
-            version = "0.0.1"
-            authors = []
+                [package]
+                name = "foo"
+                version = "0.0.1"
+                authors = []
+                edition = "2018"
 
-            [lib]
-            edition = "2018"
-        "#,
-        ).file("src/lib.rs", "")
+                [lib]
+                edition = "2015"
+            "#,
+        ).file(
+            "src/lib.rs",
+            "
+                pub fn async() {}
+                pub fn try() {}
+                pub fn await() {}
+            "
+        )
         .build();
 
-    p.cargo("build -v")
-        .masquerade_as_nightly_cargo()
-        .with_status(101)
-        .with_stderr(
-            "\
-error: failed to parse manifest at `[..]`
-
-Caused by:
-  editions are unstable
-
-Caused by:
-  feature `edition` is required
-
-consider adding `cargo-features = [\"edition\"]` to the manifest
-",
-        ).run();
+    p.cargo("build -v").run();
 }
 
 #[test]