Auto merge of #9732 - djc:rust-version-docs, r=ehuss

Stabilize the rust-version field

I've tried to make the documentation here fairly comprehensive. I've also updated the first version for the 2021 edition, which should now be stable pending substantial unforeseen changes.

See #8072.

Author: bors

CHANGELOG.md

@@ -5,6 +5,8 @@
 
 ### Added
 
+- Added support for the [`rust-version`](https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field)
+  field in a crate's metadata and the `--ignore-rust-version` command line option.
 - Build scripts can now pass additional linker arguments for binaries or all
   linkable targets. [docs](https://doc.rust-lang.org/nightly/cargo/reference/build-scripts.html#outputs-of-the-build-script)
   [#9557](https://github.com/rust-lang/cargo/pull/9557)

src/cargo/core/features.rs

@@ -166,8 +166,7 @@ impl Edition {
         match self {
             Edition2015 => None,
             Edition2018 => Some(semver::Version::new(1, 31, 0)),
-            // FIXME: This will likely be 1.56, update when that seems more likely.
-            Edition2021 => Some(semver::Version::new(1, 62, 0)),
+            Edition2021 => Some(semver::Version::new(1, 56, 0)),
         }
     }
 
@@ -396,7 +395,7 @@ features! {
     (unstable, strip, "", "reference/unstable.html#profile-strip-option"),
 
     // Specifying a minimal 'rust-version' attribute for crates
-    (unstable, rust_version, "", "reference/unstable.html#rust-version"),
+    (stable, rust_version, "1.56", "reference/manifest.html#the-rust-version-field"),
 
     // Support for 2021 edition.
     (unstable, edition2021, "", "reference/unstable.html#edition-2021"),

src/cargo/util/command_prelude.rs

@@ -218,7 +218,7 @@ pub trait AppExt: Sized {
     fn arg_ignore_rust_version(self) -> Self {
         self._arg(opt(
             "ignore-rust-version",
-            "Ignore `rust-version` specification in packages (unstable)",
+            "Ignore `rust-version` specification in packages",
         ))
     }
 
@@ -533,12 +533,6 @@ pub trait ArgMatchesExt {
             honor_rust_version: !self._is_present("ignore-rust-version"),
         };
 
-        if !opts.honor_rust_version {
-            config
-                .cli_unstable()
-                .fail_if_stable_opt("--ignore-rust-version", 8072)?;
-        }
-
         if let Some(ws) = workspace {
             self.check_optional_opts(ws, &opts)?;
         } else if self.is_present_with_zero_values("package") {

src/cargo/util/toml/mod.rs

@@ -1122,46 +1122,25 @@ impl TomlManifest {
         }
 
         let rust_version = if let Some(rust_version) = &project.rust_version {
-            if features.require(Feature::rust_version()).is_err() {
-                let mut msg =
-                    "`rust-version` is not supported on this version of Cargo and will be ignored"
-                        .to_string();
-                if config.nightly_features_allowed {
-                    msg.push_str(
-                        "\n\n\
-                        consider adding `cargo-features = [\"rust-version\"]` to the manifest",
-                    );
-                } else {
-                    msg.push_str(
-                        "\n\n\
-                        this Cargo does not support nightly features, but if you\n\
-                        switch to nightly channel you can add\n\
-                        `cargo-features = [\"rust-version\"]` to enable this feature",
-                    );
-                }
-                warnings.push(msg);
-                None
-            } else {
-                let req = match semver::VersionReq::parse(rust_version) {
-                    // Exclude semver operators like `^` and pre-release identifiers
-                    Ok(req) if rust_version.chars().all(|c| c.is_ascii_digit() || c == '.') => req,
-                    _ => bail!("`rust-version` must be a value like \"1.32\""),
-                };
-                if let Some(first_version) = edition.first_version() {
-                    let unsupported =
-                        semver::Version::new(first_version.major, first_version.minor - 1, 9999);
-                    if req.matches(&unsupported) {
-                        bail!(
-                            "rust-version {} is older than first version ({}) required by \
-                                the specified edition ({})",
-                            rust_version,
-                            first_version,
-                            edition,
-                        )
-                    }
+            let req = match semver::VersionReq::parse(rust_version) {
+                // Exclude semver operators like `^` and pre-release identifiers
+                Ok(req) if rust_version.chars().all(|c| c.is_ascii_digit() || c == '.') => req,
+                _ => bail!("`rust-version` must be a value like \"1.32\""),
+            };
+            if let Some(first_version) = edition.first_version() {
+                let unsupported =
+                    semver::Version::new(first_version.major, first_version.minor - 1, 9999);
+                if req.matches(&unsupported) {
+                    bail!(
+                        "rust-version {} is older than first version ({}) required by \
+                            the specified edition ({})",
+                        rust_version,
+                        first_version,
+                        edition,
+                    )
                 }
-                Some(rust_version.clone())
             }
+            Some(rust_version.clone())
         } else {
             None
         };

src/doc/man/cargo-bench.md

@@ -83,6 +83,8 @@ target.
 
 {{> options-target-triple }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options

src/doc/man/cargo-build.md

@@ -35,6 +35,8 @@ they have `required-features` that are missing.
 
 {{> options-release }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options

src/doc/man/cargo-check.md

@@ -42,6 +42,8 @@ they have `required-features` that are missing.
 
 {{> options-profile }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options

src/doc/man/cargo-doc.md

@@ -64,6 +64,8 @@ flag and will always document the given target.
 
 {{> options-release }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options

src/doc/man/cargo-fix.md

@@ -122,6 +122,8 @@ When no target selection options are given, `cargo fix` will fix all targets
 
 {{> options-profile }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options

src/doc/man/cargo-run.md

@@ -50,6 +50,8 @@ Run the specified example.
 
 {{> options-release }}
 
+{{> options-ignore-rust-version }}
+
 {{/options}}
 
 ### Output Options