fix(toml): Error on [project] in Edition 2024

src/bin/cargo/commands/fix.rs

@@ -1,5 +1,6 @@
 use crate::command_prelude::*;
 
+use cargo::core::Workspace;
 use cargo::ops;
 
 pub fn cli() -> Command {
@@ -60,7 +61,6 @@ pub fn cli() -> Command {
 }
 
 pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
-    let ws = args.workspace(gctx)?;
     // This is a legacy behavior that causes `cargo fix` to pass `--test`.
     let test = matches!(
         args.get_one::<String>("profile").map(String::as_str),
@@ -70,6 +70,9 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
 
     // Unlike other commands default `cargo fix` to all targets to fix as much
     // code as we can.
+    let root_manifest = args.root_manifest(gctx)?;
+    let mut ws = Workspace::new(&root_manifest, gctx)?;
+    ws.set_honor_rust_version(args.honor_rust_version());
     let mut opts = args.compile_options(gctx, mode, Some(&ws), ProfileChecking::LegacyTestOnly)?;
 
     if !opts.filter.is_specific() {
@@ -78,7 +81,9 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
     }
 
     ops::fix(
+        gctx,
         &ws,
+        &root_manifest,
         &mut ops::FixOptions {
             edition: args.flag("edition"),
             idioms: args.flag("edition-idioms"),

src/cargo/core/workspace.rs

@@ -611,6 +611,10 @@ impl<'gctx> Workspace<'gctx> {
         self.honor_rust_version = honor_rust_version;
     }
 
+    pub fn honor_rust_version(&self) -> Option<bool> {
+        self.honor_rust_version
+    }
+
     pub fn resolve_honors_rust_version(&self) -> bool {
         self.gctx().cli_unstable().msrv_policy && self.honor_rust_version.unwrap_or(true)
     }

src/cargo/ops/fix.rs

@@ -53,7 +53,8 @@ use tracing::{debug, trace, warn};
 use crate::core::compiler::RustcTargetData;
 use crate::core::resolver::features::{DiffMap, FeatureOpts, FeatureResolver, FeaturesFor};
 use crate::core::resolver::{HasDevUnits, Resolve, ResolveBehavior};
-use crate::core::{Edition, MaybePackage, PackageId, Workspace};
+use crate::core::PackageIdSpecQuery as _;
+use crate::core::{Edition, MaybePackage, Package, PackageId, Workspace};
 use crate::ops::resolve::WorkspaceResolve;
 use crate::ops::{self, CompileOptions};
 use crate::util::diagnostic_server::{Message, RustfixDiagnosticServer};
@@ -87,11 +88,26 @@ pub struct FixOptions {
     pub broken_code: bool,
 }
 
-pub fn fix(ws: &Workspace<'_>, opts: &mut FixOptions) -> CargoResult<()> {
-    check_version_control(ws.gctx(), opts)?;
+pub fn fix(
+    gctx: &GlobalContext,
+    original_ws: &Workspace<'_>,
+    root_manifest: &Path,
+    opts: &mut FixOptions,
+) -> CargoResult<()> {
+    check_version_control(gctx, opts)?;
+
     if opts.edition {
-        check_resolver_change(ws, opts)?;
+        let specs = opts.compile_opts.spec.to_package_id_specs(&original_ws)?;
+        let members: Vec<&Package> = original_ws
+            .members()
+            .filter(|m| specs.iter().any(|spec| spec.matches(m.package_id())))
+            .collect();
+        migrate_manifests(original_ws, &members)?;
+
+        check_resolver_change(&original_ws, opts)?;
     }
+    let mut ws = Workspace::new(&root_manifest, gctx)?;
+    ws.set_honor_rust_version(original_ws.honor_rust_version());
 
     // Spin up our lock server, which our subprocesses will use to synchronize fixes.
     let lock_server = LockServer::new()?;
@@ -128,7 +144,7 @@ pub fn fix(ws: &Workspace<'_>, opts: &mut FixOptions) -> CargoResult<()> {
         server.configure(&mut wrapper);
     }
 
-    let rustc = ws.gctx().load_global_rustc(Some(ws))?;
+    let rustc = ws.gctx().load_global_rustc(Some(&ws))?;
     wrapper.arg(&rustc.path);
     // This is calling rustc in cargo fix-proxy-mode, so it also need to retry.
     // The argfile handling are located at `FixArgs::from_args`.
@@ -138,7 +154,7 @@ pub fn fix(ws: &Workspace<'_>, opts: &mut FixOptions) -> CargoResult<()> {
     // repeating build until there are no more changes to be applied
     opts.compile_opts.build_config.primary_unit_rustc = Some(wrapper);
 
-    ops::compile(ws, &opts.compile_opts)?;
+    ops::compile(&ws, &opts.compile_opts)?;
     Ok(())
 }
 
@@ -215,6 +231,62 @@ fn check_version_control(gctx: &GlobalContext, opts: &FixOptions) -> CargoResult
     );
 }
 
+fn migrate_manifests(ws: &Workspace<'_>, pkgs: &[&Package]) -> CargoResult<()> {
+    for pkg in pkgs {
+        let existing_edition = pkg.manifest().edition();
+        let prepare_for_edition = existing_edition.saturating_next();
+        if existing_edition == prepare_for_edition
+            || (!prepare_for_edition.is_stable() && !ws.gctx().nightly_features_allowed)
+        {
+            continue;
+        }
+        let file = pkg.manifest_path();
+        let file = file.strip_prefix(ws.root()).unwrap_or(file);
+        let file = file.display();
+        ws.gctx().shell().status(
+            "Migrating",
+            format!("{file} from {existing_edition} edition to {prepare_for_edition}"),
+        )?;
+
+        if Edition::Edition2024 <= prepare_for_edition {
+            let mut document = pkg.manifest().document().clone().into_mut();
+            let mut fixes = 0;
+
+            let root = document.as_table_mut();
+            if rename_table(root, "project", "package") {
+                fixes += 1;
+            }
+
+            if 0 < fixes {
+                let verb = if fixes == 1 { "fix" } else { "fixes" };
+                let msg = format!("{file} ({fixes} {verb})");
+                ws.gctx().shell().status("Fixed", msg)?;
+
+                let s = document.to_string();
+                let new_contents_bytes = s.as_bytes();
+                cargo_util::paths::write_atomic(pkg.manifest_path(), new_contents_bytes)?;
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn rename_table(parent: &mut dyn toml_edit::TableLike, old: &str, new: &str) -> bool {
+    let Some(old_key) = parent.key(old).cloned() else {
+        return false;
+    };
+
+    let project = parent.remove(old).expect("returned early");
+    if !parent.contains_key(new) {
+        parent.insert(new, project);
+        let mut new_key = parent.key_mut(new).expect("just inserted");
+        *new_key.dotted_decor_mut() = old_key.dotted_decor().clone();
+        *new_key.leaf_decor_mut() = old_key.leaf_decor().clone();
+    }
+    true
+}
+
 fn check_resolver_change(ws: &Workspace<'_>, opts: &FixOptions) -> CargoResult<()> {
     let root = ws.root_maybe();
     match root {

src/cargo/util/toml/mod.rs

@@ -935,26 +935,9 @@ fn to_real_manifest(
         );
     };
 
-    let original_package = match (&original_toml.package, &original_toml.project) {
-        (Some(_), Some(project)) => {
-            warnings.push(format!(
-                "manifest at `{}` contains both `project` and `package`, \
-                    this could become a hard error in the future",
-                package_root.display()
-            ));
-            project.clone()
-        }
-        (Some(package), None) => package.clone(),
-        (None, Some(project)) => {
-            warnings.push(format!(
-                "manifest at `{}` contains `[project]` instead of `[package]`, \
-                                this could become a hard error in the future",
-                package_root.display()
-            ));
-            project.clone()
-        }
-        (None, None) => bail!("no `package` section found"),
-    };
+    let original_package = original_toml
+        .package()
+        .ok_or_else(|| anyhow::format_err!("no `package` section found"))?;
 
     let package_name = &original_package.name;
     if package_name.contains(':') {
@@ -1044,6 +1027,16 @@ fn to_real_manifest(
         )));
     }
 
+    if original_toml.project.is_some() {
+        if Edition::Edition2024 <= edition {
+            anyhow::bail!(
+                "`[project]` is not supported as of the 2024 Edition, please use `[package]`"
+            );
+        } else {
+            warnings.push(format!("`[project]` is deprecated in favor of `[package]`"));
+        }
+    }
+
     if resolved_package.metabuild.is_some() {
         features.require(Feature::metabuild())?;
     }

tests/testsuite/check.rs

@@ -979,6 +979,63 @@ fn rustc_workspace_wrapper_excludes_published_deps() {
         .run();
 }
 
+#[cargo_test]
+fn warn_manifest_with_project() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [project]
+                name = "foo"
+                version = "0.0.1"
+                edition = "2015"
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .build();
+
+    p.cargo("check")
+        .with_stderr(
+            "\
+[WARNING] `[project]` is deprecated in favor of `[package]`
+[CHECKING] foo v0.0.1 ([CWD])
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
+",
+        )
+        .run();
+}
+
+#[cargo_test(nightly, reason = "edition2024")]
+fn error_manifest_with_project_on_2024() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["edition2024"]
+
+                [project]
+                name = "foo"
+                version = "0.0.1"
+                edition = "2024"
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .build();
+
+    p.cargo("check")
+        .masquerade_as_nightly_cargo(&["edition2024"])
+        .with_status(101)
+        .with_stderr(
+            "\
+[ERROR] failed to parse manifest at `[CWD]/Cargo.toml`
+
+Caused by:
+  `[project]` is not supported as of the 2024 Edition, please use `[package]`
+",
+        )
+        .run();
+}
+
 #[cargo_test]
 fn warn_manifest_package_and_project() {
     let p = project()
@@ -1002,7 +1059,7 @@ fn warn_manifest_package_and_project() {
     p.cargo("check")
         .with_stderr(
             "\
-[WARNING] manifest at `[CWD]` contains both `project` and `package`, this could become a hard error in the future
+[WARNING] `[project]` is deprecated in favor of `[package]`
 [CHECKING] foo v0.0.1 ([CWD])
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
 ",
@@ -1065,32 +1122,6 @@ fn git_manifest_package_and_project() {
         .run();
 }
 
-#[cargo_test]
-fn warn_manifest_with_project() {
-    let p = project()
-        .file(
-            "Cargo.toml",
-            r#"
-                [project]
-                name = "foo"
-                version = "0.0.1"
-                edition = "2015"
-            "#,
-        )
-        .file("src/main.rs", "fn main() {}")
-        .build();
-
-    p.cargo("check")
-        .with_stderr(
-            "\
-[WARNING] manifest at `[CWD]` contains `[project]` instead of `[package]`, this could become a hard error in the future
-[CHECKING] foo v0.0.1 ([CWD])
-[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [..]
-",
-        )
-        .run();
-}
-
 #[cargo_test]
 fn git_manifest_with_project() {
     let p = project();