Auto merge of #9800 - ehuss:stabilize-2021, r=alexcrichton

Stabilize 2021 edition

This stabilizes the 2021 edition.

Closes #9781

Author: bors

src/cargo/core/compiler/build_context/target_info.rs

@@ -47,6 +47,8 @@ pub struct TargetInfo {
     pub rustdocflags: Vec<String>,
     /// Whether or not rustc supports the `-Csplit-debuginfo` flag.
     pub supports_split_debuginfo: bool,
+    /// Whether or not rustc supports the `--force-warn` flag. Remove after 1.56 is stable.
+    pub supports_force_warn: bool,
 }
 
 /// Kind of each file generated by a Unit, part of `FileType`.
@@ -178,6 +180,12 @@ impl TargetInfo {
                 extra_fingerprint,
             )
             .is_ok();
+        let supports_force_warn = rustc
+            .cached_output(
+                process.clone().arg("--force-warn=rust-2021-compatibility"),
+                extra_fingerprint,
+            )
+            .is_ok();
 
         process.arg("--print=sysroot");
         process.arg("--print=cfg");
@@ -253,6 +261,7 @@ impl TargetInfo {
             )?,
             cfg,
             supports_split_debuginfo,
+            supports_force_warn,
         })
     }
 

src/cargo/core/features.rs

@@ -139,6 +139,7 @@ pub enum Edition {
 // - Set LATEST_STABLE to the new version.
 // - Update `is_stable` to `true`.
 // - Set the editionNNNN feature to stable in the features macro below.
+// - Update any tests that are affected.
 // - Update the man page for the --edition flag.
 // - Update unstable.md to move the edition section to the bottom.
 // - Update the documentation:
@@ -150,9 +151,9 @@ impl Edition {
     /// The latest edition that is unstable.
     ///
     /// This is `None` if there is no next unstable edition.
-    pub const LATEST_UNSTABLE: Option<Edition> = Some(Edition::Edition2021);
+    pub const LATEST_UNSTABLE: Option<Edition> = None;
     /// The latest stable edition.
-    pub const LATEST_STABLE: Edition = Edition::Edition2018;
+    pub const LATEST_STABLE: Edition = Edition::Edition2021;
     /// Possible values allowed for the `--edition` CLI flag.
     ///
     /// This requires a static value due to the way clap works, otherwise I
@@ -176,7 +177,7 @@ impl Edition {
         match self {
             Edition2015 => true,
             Edition2018 => true,
-            Edition2021 => false,
+            Edition2021 => true,
         }
     }
 
@@ -398,7 +399,7 @@ features! {
     (stable, rust_version, "1.56", "reference/manifest.html#the-rust-version-field"),
 
     // Support for 2021 edition.
-    (unstable, edition2021, "", "reference/unstable.html#edition-2021"),
+    (stable, edition2021, "1.56", "reference/manifest.html#the-edition-field"),
 
     // Allow to specify per-package targets (compile kinds)
     (unstable, per_package_target, "", "reference/unstable.html#per-package-target"),

src/cargo/ops/fix.rs

@@ -51,7 +51,7 @@ use log::{debug, trace, warn};
 use rustfix::diagnostics::Diagnostic;
 use rustfix::{self, CodeFix};
 
-use crate::core::compiler::RustcTargetData;
+use crate::core::compiler::{CompileKind, RustcTargetData, TargetInfo};
 use crate::core::resolver::features::{DiffMap, FeatureOpts, FeatureResolver};
 use crate::core::resolver::{HasDevUnits, Resolve, ResolveBehavior};
 use crate::core::{Edition, MaybePackage, Workspace};
@@ -67,6 +67,7 @@ const FIX_ENV: &str = "__CARGO_FIX_PLZ";
 const BROKEN_CODE_ENV: &str = "__CARGO_FIX_BROKEN_CODE";
 const EDITION_ENV: &str = "__CARGO_FIX_EDITION";
 const IDIOMS_ENV: &str = "__CARGO_FIX_IDIOMS";
+const SUPPORTS_FORCE_WARN: &str = "__CARGO_SUPPORTS_FORCE_WARN";
 
 pub struct FixOptions {
     pub edition: bool,
@@ -122,6 +123,17 @@ pub fn fix(ws: &Workspace<'_>, opts: &mut FixOptions) -> CargoResult<()> {
     let rustc = ws.config().load_global_rustc(Some(ws))?;
     wrapper.arg(&rustc.path);
 
+    // Remove this once 1.56 is stabilized.
+    let target_info = TargetInfo::new(
+        ws.config(),
+        &opts.compile_opts.build_config.requested_kinds,
+        &rustc,
+        CompileKind::Host,
+    )?;
+    if target_info.supports_force_warn {
+        wrapper.env(SUPPORTS_FORCE_WARN, "1");
+    }
+
     // primary crates are compiled using a cargo subprocess to do extra work of applying fixes and
     // repeating build until there are no more changes to be applied
     opts.compile_opts.build_config.primary_unit_rustc = Some(wrapper);
@@ -362,7 +374,7 @@ pub fn fix_maybe_exec_rustc(config: &Config) -> CargoResult<bool> {
     // that we have to back it all out.
     if !fixes.files.is_empty() {
         let mut cmd = rustc.build_command();
-        args.apply(&mut cmd, config);
+        args.apply(&mut cmd);
         cmd.arg("--error-format=json");
         debug!("calling rustc for final verification: {:?}", cmd);
         let output = cmd.output().context("failed to spawn rustc")?;
@@ -403,7 +415,7 @@ pub fn fix_maybe_exec_rustc(config: &Config) -> CargoResult<bool> {
     // - If `--broken-code`, show the error messages.
     // - If the fix succeeded, show any remaining warnings.
     let mut cmd = rustc.build_command();
-    args.apply(&mut cmd, config);
+    args.apply(&mut cmd);
     for arg in args.format_args {
         // Add any json/error format arguments that Cargo wants. This allows
         // things like colored output to work correctly.
@@ -497,7 +509,7 @@ fn rustfix_crate(
             // We'll generate new errors below.
             file.errors_applying_fixes.clear();
         }
-        rustfix_and_fix(&mut fixes, rustc, filename, args, config)?;
+        rustfix_and_fix(&mut fixes, rustc, filename, args)?;
         let mut progress_yet_to_be_made = false;
         for (path, file) in fixes.files.iter_mut() {
             if file.errors_applying_fixes.is_empty() {
@@ -539,15 +551,14 @@ fn rustfix_and_fix(
     rustc: &ProcessBuilder,
     filename: &Path,
     args: &FixArgs,
-    config: &Config,
 ) -> Result<(), Error> {
     // If not empty, filter by these lints.
     // TODO: implement a way to specify this.
     let only = HashSet::new();
 
     let mut cmd = rustc.build_command();
     cmd.arg("--error-format=json");
-    args.apply(&mut cmd, config);
+    args.apply(&mut cmd);
     debug!(
         "calling rustc to collect suggestions and validate previous fixes: {:?}",
         cmd
@@ -822,10 +833,10 @@ impl FixArgs {
         })
     }
 
-    fn apply(&self, cmd: &mut Command, config: &Config) {
+    fn apply(&self, cmd: &mut Command) {
         cmd.arg(&self.file);
         cmd.args(&self.other);
-        if self.prepare_for_edition.is_some() && config.nightly_features_allowed {
+        if self.prepare_for_edition.is_some() && env::var_os(SUPPORTS_FORCE_WARN).is_some() {
             // When migrating an edition, we don't want to fix other lints as
             // they can sometimes add suggestions that fail to apply, causing
             // the entire migration to fail. But those lints aren't needed to
@@ -844,7 +855,7 @@ impl FixArgs {
 
         if let Some(edition) = self.prepare_for_edition {
             if edition.supports_compat_lint() {
-                if config.nightly_features_allowed {
+                if env::var_os(SUPPORTS_FORCE_WARN).is_some() {
                     cmd.arg("--force-warn")
                         .arg(format!("rust-{}-compatibility", edition))
                         .arg("-Zunstable-options");

src/doc/man/generated_txt/cargo-init.txt

@@ -30,7 +30,7 @@ OPTIONS
            Create a package with a library target (src/lib.rs).
 
        --edition edition
-           Specify the Rust edition to use. Default is 2018. Possible values:
+           Specify the Rust edition to use. Default is 2021. Possible values:
            2015, 2018, 2021
 
        --name name

src/doc/man/generated_txt/cargo-new.txt

@@ -25,7 +25,7 @@ OPTIONS
            Create a package with a library target (src/lib.rs).
 
        --edition edition
-           Specify the Rust edition to use. Default is 2018. Possible values:
+           Specify the Rust edition to use. Default is 2021. Possible values:
            2015, 2018, 2021
 
        --name name

src/doc/man/includes/options-new.md

@@ -10,7 +10,7 @@ Create a package with a library target (`src/lib.rs`).
 {{/option}}
 
 {{#option "`--edition` _edition_" }}
-Specify the Rust edition to use. Default is 2018.
+Specify the Rust edition to use. Default is 2021.
 Possible values: 2015, 2018, 2021
 {{/option}}
 

src/doc/src/commands/cargo-init.md

@@ -39,7 +39,7 @@ This is the default behavior.</dd>
 
 
 <dt class="option-term" id="option-cargo-init---edition"><a class="option-anchor" href="#option-cargo-init---edition"></a><code>--edition</code> <em>edition</em></dt>
-<dd class="option-desc">Specify the Rust edition to use. Default is 2018.
+<dd class="option-desc">Specify the Rust edition to use. Default is 2021.
 Possible values: 2015, 2018, 2021</dd>
 
 

src/doc/src/commands/cargo-new.md

@@ -34,7 +34,7 @@ This is the default behavior.</dd>
 
 
 <dt class="option-term" id="option-cargo-new---edition"><a class="option-anchor" href="#option-cargo-new---edition"></a><code>--edition</code> <em>edition</em></dt>
-<dd class="option-desc">Specify the Rust edition to use. Default is 2018.
+<dd class="option-desc">Specify the Rust edition to use. Default is 2021.
 Possible values: 2015, 2018, 2021</dd>
 
 

src/doc/src/reference/manifest.md

@@ -133,12 +133,12 @@ examples, etc.
 ```toml
 [package]
 # ...
-edition = '2018'
+edition = '2021'
 ```
 
 Most manifests have the `edition` field filled in automatically by [`cargo new`]
 with the latest stable edition. By default `cargo new` creates a manifest with
-the 2018 edition currently.
+the 2021 edition currently.
 
 If the `edition` field is not present in `Cargo.toml`, then the 2015 edition is
 assumed for backwards compatibility. Note that all manifests

src/doc/src/reference/resolver.md

@@ -408,8 +408,9 @@ version = "1.0.0"
 resolver = "2"
 ```
 
-The version `"1"` resolver is the original resolver that shipped with Cargo up
-to version 1.50, and is the default if the `resolver` is not specified.
+The version `"1"` resolver is the original resolver that shipped with Cargo up to version 1.50.
+The default is `"2"` if the root package specifies [`edition = "2021"`](manifest.md#the-edition-field) or a newer edition.
+Otherwise the default is `"1"`.
 
 The version `"2"` resolver introduces changes in [feature
 unification](#features). See the [features chapter][features-2] for more