Add "-Zpublic-dependency" for public-dependency feature

src/cargo/core/compiler/mod.rs

@@ -89,7 +89,7 @@ use crate::core::compiler::future_incompat::FutureIncompatReport;
 pub use crate::core::compiler::unit::{Unit, UnitInterner};
 use crate::core::manifest::TargetSourcePath;
 use crate::core::profiles::{PanicStrategy, Profile, StripInner};
-use crate::core::{Feature, PackageId, Target, Verbosity};
+use crate::core::{PackageId, Target, Verbosity};
 use crate::util::errors::{CargoResult, VerboseError};
 use crate::util::interning::InternedString;
 use crate::util::machine_message::{self, Message};
@@ -1437,14 +1437,7 @@ pub fn extern_args(
         |dep: &UnitDep, extern_crate_name: InternedString, noprelude: bool| -> CargoResult<()> {
             let mut value = OsString::new();
             let mut opts = Vec::new();
-            if unit
-                .pkg
-                .manifest()
-                .unstable_features()
-                .require(Feature::public_dependency())
-                .is_ok()
-                && !dep.public
-                && unit.target.is_lib()
+            if !dep.public && unit.target.is_lib() && cx.bcx.config.cli_unstable().public_dependency
             {
                 opts.push("priv");
                 *unstable_opts = true;

src/cargo/core/features.rs

@@ -764,6 +764,7 @@ unstable_cli_options!(
     panic_abort_tests: bool = ("Enable support to run tests with -Cpanic=abort"),
     precise_pre_release: bool = ("Enable pre-release versions to be selected with `update --precise`"),
     profile_rustflags: bool = ("Enable the `rustflags` option in profiles in .cargo/config.toml file"),
+    public_dependency: bool = ("Respect a dependency's `public` field in Cargo.toml to control public/private dependencies"),
     publish_timeout: bool = ("Enable the `publish.timeout` key in .cargo/config.toml file"),
     rustdoc_map: bool = ("Allow passing external documentation mappings to rustdoc"),
     rustdoc_scrape_examples: bool = ("Allows Rustdoc to scrape code examples from reverse-dependencies"),
@@ -1140,6 +1141,7 @@ impl CliUnstable {
             "mtime-on-use" => self.mtime_on_use = parse_empty(k, v)?,
             "no-index-update" => self.no_index_update = parse_empty(k, v)?,
             "panic-abort-tests" => self.panic_abort_tests = parse_empty(k, v)?,
+            "public-dependency" => self.public_dependency = parse_empty(k, v)?,
             "profile-rustflags" => self.profile_rustflags = parse_empty(k, v)?,
             "precise-pre-release" => self.precise_pre_release = parse_empty(k, v)?,
             "trim-paths" => self.trim_paths = parse_empty(k, v)?,

src/cargo/core/workspace.rs

@@ -449,7 +449,6 @@ impl<'cfg> Workspace<'cfg> {
                             // NOTE: Since we use ConfigRelativePath, this root isn't used as
                             // any relative paths are resolved before they'd be joined with root.
                             Path::new("unused-relative-path"),
-                            self.unstable_features(),
                             /* kind */ None,
                         )
                     })

src/cargo/ops/cargo_package.rs

@@ -10,8 +10,8 @@ use crate::core::compiler::{BuildConfig, CompileMode, DefaultExecutor, Executor}
 use crate::core::manifest::Target;
 use crate::core::resolver::CliFeatures;
 use crate::core::{registry::PackageRegistry, resolver::HasDevUnits};
-use crate::core::{Feature, Shell, Verbosity, Workspace};
 use crate::core::{Package, PackageId, PackageSet, Resolve, SourceId};
+use crate::core::{Shell, Verbosity, Workspace};
 use crate::sources::PathSource;
 use crate::util::cache_lock::CacheLockMode;
 use crate::util::config::JobsConfig;
@@ -911,12 +911,7 @@ fn run_verify(
     let pkg_fingerprint = hash_all(&dst)?;
     let ws = Workspace::ephemeral(new_pkg, config, None, true)?;
 
-    let rustc_args = if pkg
-        .manifest()
-        .unstable_features()
-        .require(Feature::public_dependency())
-        .is_ok()
-    {
+    let rustc_args = if ws.config().cli_unstable().public_dependency {
         // FIXME: Turn this on at some point in the future
         //Some(vec!["-D exported_private_dependencies".to_string()])
         Some(vec![])

src/cargo/util/toml/mod.rs

@@ -9,8 +9,8 @@ use crate::AlreadyPrintedError;
 use anyhow::{anyhow, bail, Context as _};
 use cargo_platform::Platform;
 use cargo_util::paths;
-use cargo_util_schemas::manifest;
 use cargo_util_schemas::manifest::RustVersion;
+use cargo_util_schemas::manifest::{self, InheritableDependency, TomlDependency};
 use itertools::Itertools;
 use lazycell::LazyCell;
 use pathdiff::diff_paths;
@@ -104,13 +104,30 @@ fn read_manifest_from_str(
     let package_root = manifest_file.parent().unwrap();
 
     let mut unused = BTreeSet::new();
+    let mut public_deps_without_z = BTreeSet::new();
+
     let deserializer = toml::de::Deserializer::new(contents);
     let manifest: manifest::TomlManifest = match serde_ignored::deserialize(deserializer, |path| {
         let mut key = String::new();
         stringify(&mut key, &path);
         unused.insert(key);
     }) {
-        Ok(manifest) => manifest,
+        Ok(manifest) => {
+            let mut manifest: manifest::TomlManifest = manifest;
+            if let Some(deps) = &mut manifest.dependencies {
+                for (name, dep) in deps {
+                    if let InheritableDependency::Value(toml_dep) = dep {
+                        if let TomlDependency::Detailed(d) = toml_dep {
+                            if !config.cli_unstable().public_dependency && d.public.is_some() {
+                                d.public = None;
+                                public_deps_without_z.insert(name.clone());
+                            }
+                        }
+                    }
+                }
+            }
+            manifest
+        }
         Err(e) => {
             let Some(span) = e.span() else {
                 return Err(e.into());
@@ -168,6 +185,13 @@ fn read_manifest_from_str(
             }
         }
     };
+    let public_warn = |warnings: &mut Warnings| {
+        for name in public_deps_without_z {
+            warnings.add_warning(format!(
+                "{name} uses 'public' specifier, pass `-Zpublic-dependency` to enable support for it",
+            ))
+        }
+    };
 
     if let Some(deps) = manifest
         .workspace
@@ -187,6 +211,7 @@ fn read_manifest_from_str(
         let (mut manifest, paths) =
             to_real_manifest(manifest, embedded, source_id, package_root, config)?;
         add_unused(manifest.warnings_mut());
+        public_warn(manifest.warnings_mut());
         if manifest.targets().iter().all(|t| t.is_custom_build()) {
             bail!(
                 "no targets specified in the manifest\n\
@@ -198,6 +223,7 @@ fn read_manifest_from_str(
     } else {
         let (mut m, paths) = to_virtual_manifest(manifest, source_id, package_root, config)?;
         add_unused(m.warnings_mut());
+        public_warn(m.warnings_mut());
         Ok((EitherManifest::Virtual(m), paths))
     };
 
@@ -678,7 +704,6 @@ pub fn to_real_manifest(
         nested_paths: &mut nested_paths,
         config,
         warnings: &mut warnings,
-        features: &features,
         platform: None,
         root: package_root,
     };
@@ -1153,7 +1178,6 @@ fn to_virtual_manifest(
             config,
             warnings: &mut warnings,
             platform: None,
-            features: &features,
             root,
         };
         (replace(&me, &mut cx)?, patch(&me, &mut cx)?)
@@ -1302,7 +1326,6 @@ struct Context<'a, 'b> {
     warnings: &'a mut Vec<String>,
     platform: Option<Platform>,
     root: &'a Path,
-    features: &'a Features,
 }
 
 fn verify_lints(lints: Option<manifest::TomlLints>) -> CargoResult<Option<manifest::TomlLints>> {
@@ -1709,7 +1732,6 @@ pub(crate) fn to_dependency<P: ResolveToPath + Clone>(
     warnings: &mut Vec<String>,
     platform: Option<Platform>,
     root: &Path,
-    features: &Features,
     kind: Option<DepKind>,
 ) -> CargoResult<Dependency> {
     dep_to_dependency(
@@ -1723,7 +1745,6 @@ pub(crate) fn to_dependency<P: ResolveToPath + Clone>(
             warnings,
             platform,
             root,
-            features,
         },
         kind,
     )
@@ -1944,7 +1965,17 @@ fn detailed_dep_to_dependency<P: ResolveToPath + Clone>(
     }
 
     if let Some(p) = orig.public {
-        cx.features.require(Feature::public_dependency())?;
+        if !cx.config.nightly_features_allowed {
+            bail!(
+                "Consider trying a newer version of Cargo (this may require the nightly release)."
+            );
+        }
+        if !cx.config.cli_unstable().public_dependency {
+            bail!(format!(
+                "{name} uses 'public' specifier, pass `-Zpublic-dependency` to enable support for it",
+                name = dep.name_in_toml(),
+            ));
+        }
 
         if dep.kind() != DepKind::Normal {
             bail!("'public' specifier can only be used on regular dependencies, not {:?} dependencies", dep.kind());

src/doc/src/reference/unstable.md

@@ -296,11 +296,9 @@ The 'public-dependency' feature allows marking dependencies as 'public'
 or 'private'. When this feature is enabled, additional information is passed to rustc to allow
 the 'exported_private_dependencies' lint to function properly.
 
-This requires the appropriate key to be set in `cargo-features`:
+Pass `-Zpublic-dependency` to cargo to enable support for it.
 
 ```toml
-cargo-features = ["public-dependency"]
-
 [dependencies]
 my_dep = { version = "1.2.3", public = true }
 private_dep = "2.0.0" # Will be 'private' by default

tests/build-std/main.rs

@@ -33,7 +33,7 @@ fn enable_build_std(e: &mut Execs, arg: Option<&str>) {
         Some(s) => format!("-Zbuild-std={}", s),
         None => "-Zbuild-std".to_string(),
     };
-    e.arg(arg);
+    e.arg(arg).arg("-Zpublic-dependency");
     e.masquerade_as_nightly_cargo(&["build-std"]);
 }
 

tests/testsuite/cargo/z_help/stdout.log

@@ -25,6 +25,7 @@ Available unstable (nightly-only) flags:
     -Z panic-abort-tests        Enable support to run tests with -Cpanic=abort
     -Z precise-pre-release      Enable pre-release versions to be selected with `update --precise`
     -Z profile-rustflags        Enable the `rustflags` option in profiles in .cargo/config.toml file
+    -Z public-dependency        Respect a dependency's `public` field in Cargo.toml to control public/private dependencies
     -Z publish-timeout          Enable the `publish.timeout` key in .cargo/config.toml file
     -Z rustdoc-map              Allow passing external documentation mappings to rustdoc
     -Z rustdoc-scrape-examples  Allows Rustdoc to scrape code examples from reverse-dependencies

tests/testsuite/cargo_add/detect_workspace_inherit_public/in/primary/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [package]
 name = "bar"
 version = "0.0.0"

tests/testsuite/cargo_add/detect_workspace_inherit_public/out/primary/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [package]
 name = "bar"
 version = "0.0.0"

tests/testsuite/cargo_add/no_public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/no_public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_no_public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_no_public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_no_public_with_public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_no_public_with_public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_public_with_no_public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/overwrite_public_with_no_public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/public/in/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]

tests/testsuite/cargo_add/public/out/Cargo.toml

@@ -1,4 +1,3 @@
-cargo-features = ["public-dependency"]
 [workspace]
 
 [package]