Implement path-bases (RFC 3529) 2/n: cargo add support

RFC: rust-lang/rfcs#3529
Tracking Issue: #14355

This PR adds the `--base` option to `cargo add` to allow adding a path dependency with a path base.

src/bin/cargo/commands/add.rs

@@ -101,6 +101,12 @@ Example uses:
                 .help("Filesystem path to local crate to add")
                 .group("selected")
                 .conflicts_with("git"),
+            clap::Arg::new("base")
+                .long("base")
+                .action(ArgAction::Set)
+                .value_name("BASE")
+                .help("The path base to use when adding from a local crate.")
+                .requires("path"),
             clap::Arg::new("git")
                 .long("git")
                 .action(ArgAction::Set)
@@ -224,6 +230,7 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
 
 fn parse_dependencies(gctx: &GlobalContext, matches: &ArgMatches) -> CargoResult<Vec<DepOp>> {
     let path = matches.get_one::<String>("path");
+    let base = matches.get_one::<String>("base");
     let git = matches.get_one::<String>("git");
     let branch = matches.get_one::<String>("branch");
     let rev = matches.get_one::<String>("rev");
@@ -329,6 +336,7 @@ fn parse_dependencies(gctx: &GlobalContext, matches: &ArgMatches) -> CargoResult
             public,
             registry: registry.clone(),
             path: path.map(String::from),
+            base: base.map(String::from),
             git: git.map(String::from),
             branch: branch.map(String::from),
             rev: rev.map(String::from),

src/cargo/ops/cargo_add/mod.rs

@@ -12,6 +12,7 @@ use std::str::FromStr;
 use anyhow::Context as _;
 use cargo_util::paths;
 use cargo_util_schemas::core::PartialVersion;
+use cargo_util_schemas::manifest::PathBaseName;
 use cargo_util_schemas::manifest::RustVersion;
 use indexmap::IndexSet;
 use itertools::Itertools;
@@ -28,6 +29,7 @@ use crate::core::Workspace;
 use crate::sources::source::QueryKind;
 use crate::util::cache_lock::CacheLockMode;
 use crate::util::style;
+use crate::util::toml::lookup_path_base;
 use crate::util::toml_mut::dependency::Dependency;
 use crate::util::toml_mut::dependency::GitSource;
 use crate::util::toml_mut::dependency::MaybeWorkspace;
@@ -270,8 +272,11 @@ pub struct DepOp {
     /// Registry for looking up dependency version
     pub registry: Option<String>,
 
-    /// Git repo for dependency
+    /// File system path for dependency
     pub path: Option<String>,
+    /// Specify a named base for a path dependency
+    pub base: Option<String>,
+
     /// Git repo for dependency
     pub git: Option<String>,
     /// Specify an alternative git branch
@@ -331,10 +336,25 @@ fn resolve_dependency(
         };
         selected
     } else if let Some(raw_path) = &arg.path {
-        let path = paths::normalize_path(&std::env::current_dir()?.join(raw_path));
-        let src = PathSource::new(&path);
+        let (path, base_name_and_value) = if let Some(base_name) = &arg.base {
+            let workspace_root = || Ok(ws.root_manifest().parent().unwrap());
+            let base_value = lookup_path_base(
+                &PathBaseName::new(base_name.clone())?,
+                gctx,
+                &workspace_root,
+                None,
+            )?;
+            (
+                base_value.join(raw_path),
+                Some((base_name.clone(), base_value)),
+            )
+        } else {
+            (std::env::current_dir()?.join(raw_path), None)
+        };
+        let path = paths::normalize_path(&path);
+        let src = PathSource::new(path);
 
-        let selected = if let Some(crate_spec) = &crate_spec {
+        let mut selected = if let Some(crate_spec) = &crate_spec {
             if let Some(v) = crate_spec.version_req() {
                 // crate specifier includes a version (e.g. `[email protected]`)
                 anyhow::bail!("cannot specify a path (`{raw_path}`) with a version (`{v}`).");
@@ -349,10 +369,15 @@ fn resolve_dependency(
             }
             selected
         } else {
-            let mut source = crate::sources::PathSource::new(&path, src.source_id()?, gctx);
+            let mut source = crate::sources::PathSource::new(&src.path, src.source_id()?, gctx);
             let package = source.root_package()?;
             Dependency::from(package.summary())
         };
+        if let Some(selected_source) = selected.source.as_mut() {
+            if let Source::Path(selected_source) = selected_source {
+                selected_source.base_name_and_value = base_name_and_value;
+            }
+        }
         selected
     } else if let Some(crate_spec) = &crate_spec {
         crate_spec.to_dependency()?

src/cargo/util/toml/mod.rs

@@ -312,7 +312,7 @@ fn normalize_toml(
         inherit_cell
             .try_borrow_with(|| load_inheritable_fields(gctx, manifest_file, &workspace_config))
     };
-    let workspace_root = || inherit().map(|fields| fields.ws_root());
+    let workspace_root = || inherit().map(|fields| fields.ws_root().as_path());
 
     if let Some(original_package) = original_toml.package() {
         let package_name = &original_package.name;
@@ -538,7 +538,7 @@ fn normalize_toml(
 fn normalize_patch<'a>(
     gctx: &GlobalContext,
     original_patch: Option<&BTreeMap<String, BTreeMap<PackageName, TomlDependency>>>,
-    workspace_root: &dyn Fn() -> CargoResult<&'a PathBuf>,
+    workspace_root: &dyn Fn() -> CargoResult<&'a Path>,
     features: &Features,
 ) -> CargoResult<Option<BTreeMap<String, BTreeMap<PackageName, TomlDependency>>>> {
     if let Some(patch) = original_patch {
@@ -757,7 +757,7 @@ fn normalize_dependencies<'a>(
     activated_opt_deps: &HashSet<&str>,
     kind: Option<DepKind>,
     inherit: &dyn Fn() -> CargoResult<&'a InheritableFields>,
-    workspace_root: &dyn Fn() -> CargoResult<&'a PathBuf>,
+    workspace_root: &dyn Fn() -> CargoResult<&'a Path>,
     package_root: &Path,
     warnings: &mut Vec<String>,
 ) -> CargoResult<Option<BTreeMap<manifest::PackageName, manifest::InheritableDependency>>> {
@@ -839,12 +839,13 @@ fn normalize_dependencies<'a>(
 fn normalize_path_dependency<'a>(
     gctx: &GlobalContext,
     detailed_dep: &mut TomlDetailedDependency,
-    workspace_root: &dyn Fn() -> CargoResult<&'a PathBuf>,
+    workspace_root: &dyn Fn() -> CargoResult<&'a Path>,
     features: &Features,
 ) -> CargoResult<()> {
     if let Some(base) = detailed_dep.base.take() {
         if let Some(path) = detailed_dep.path.as_mut() {
-            let new_path = lookup_path_base(&base, gctx, workspace_root, features)?.join(&path);
+            let new_path =
+                lookup_path_base(&base, gctx, workspace_root, Some(features))?.join(&path);
             *path = new_path.to_str().unwrap().to_string();
         } else {
             bail!("`base` can only be used with path dependencies");
@@ -2225,10 +2226,12 @@ fn to_dependency_source_id<P: ResolveToPath + Clone>(
 pub(crate) fn lookup_path_base<'a>(
     base: &PathBaseName,
     gctx: &GlobalContext,
-    workspace_root: &dyn Fn() -> CargoResult<&'a PathBuf>,
-    features: &Features,
+    workspace_root: &dyn Fn() -> CargoResult<&'a Path>,
+    features: Option<&Features>,
 ) -> CargoResult<PathBuf> {
-    features.require(Feature::path_bases())?;
+    if let Some(features) = features {
+        features.require(Feature::path_bases())?;
+    }
 
     // HACK: The `base` string is user controlled, but building the path is safe from injection
     // attacks since the `PathBaseName` type restricts the characters that can be used to exclude `.`
@@ -2240,7 +2243,7 @@ pub(crate) fn lookup_path_base<'a>(
     } else {
         // Otherwise, check the built-in bases.
         match base.as_str() {
-            "workspace" => Ok(workspace_root()?.clone()),
+            "workspace" => Ok(workspace_root()?.to_path_buf()),
             _ => bail!(
                 "path base `{base}` is undefined. \
             You must add an entry for `{base}` in the Cargo configuration [path-bases] table."

src/cargo/util/toml_mut/dependency.rs

@@ -412,10 +412,18 @@ impl Dependency {
                         table.insert("version", src.version.as_str().into());
                     }
                     Some(Source::Path(src)) => {
-                        let relpath = path_field(crate_root, &src.path);
                         if let Some(r) = src.version.as_deref() {
                             table.insert("version", r.into());
                         }
+                        let relative_to = if let Some((base_name, base_value)) =
+                            src.base_name_and_value.as_ref()
+                        {
+                            table.insert("base", base_name.into());
+                            base_value
+                        } else {
+                            crate_root
+                        };
+                        let relpath = path_field(relative_to, &src.path);
                         table.insert("path", relpath.into());
                     }
                     Some(Source::Git(src)) => {
@@ -493,12 +501,20 @@ impl Dependency {
                 Some(Source::Registry(src)) => {
                     overwrite_value(table, "version", src.version.as_str());
 
-                    for key in ["path", "git", "branch", "tag", "rev", "workspace"] {
+                    for key in ["path", "git", "branch", "tag", "rev", "workspace", "base"] {
                         table.remove(key);
                     }
                 }
                 Some(Source::Path(src)) => {
-                    let relpath = path_field(crate_root, &src.path);
+                    let relative_to =
+                        if let Some((base_name, base_value)) = src.base_name_and_value.as_ref() {
+                            overwrite_value(table, "base", base_name);
+                            base_value
+                        } else {
+                            table.remove("base");
+                            crate_root
+                        };
+                    let relpath = path_field(relative_to, &src.path);
                     overwrite_value(table, "path", relpath);
                     if let Some(r) = src.version.as_deref() {
                         overwrite_value(table, "version", r);
@@ -533,7 +549,7 @@ impl Dependency {
                         table.remove("version");
                     }
 
-                    for key in ["path", "workspace"] {
+                    for key in ["path", "workspace", "base"] {
                         table.remove(key);
                     }
                 }
@@ -552,6 +568,7 @@ impl Dependency {
                         "rev",
                         "package",
                         "default-features",
+                        "base",
                     ] {
                         table.remove(key);
                     }
@@ -812,6 +829,8 @@ impl std::fmt::Display for RegistrySource {
 pub struct PathSource {
     /// Local, absolute path.
     pub path: PathBuf,
+    /// If using a named base, the base and relative path.
+    pub base_name_and_value: Option<(String, PathBuf)>,
     /// Version requirement for when published.
     pub version: Option<String>,
 }
@@ -821,6 +840,7 @@ impl PathSource {
     pub fn new(path: impl Into<PathBuf>) -> Self {
         Self {
             path: path.into(),
+            base_name_and_value: None,
             version: None,
         }
     }
@@ -843,7 +863,11 @@ impl PathSource {
 
 impl std::fmt::Display for PathSource {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        self.path.display().fmt(f)
+        if let Some((base_name, _)) = &self.base_name_and_value {
+            write!(f, "[{base_name}]/{}", self.path.display())
+        } else {
+            self.path.display().fmt(f)
+        }
     }
 }
 

src/doc/man/cargo-add.md

@@ -10,7 +10,7 @@ cargo-add --- Add dependencies to a Cargo.toml manifest file
 ## SYNOPSIS
 
 `cargo add` [_options_] _crate_...\
-`cargo add` [_options_] `--path` _path_\
+`cargo add` [_options_] `--path` _path_ [`--base` _base_]\
 `cargo add` [_options_] `--git` _url_ [_crate_...]
 
 
@@ -63,6 +63,10 @@ Specific commit to use when adding from git.
 [Filesystem path](../reference/specifying-dependencies.html#specifying-path-dependencies) to local crate to add.
 {{/option}}
 
+{{#option "`--base` _base_" }}
+The [path base](../reference/unstable.html#path-bases) to use when adding a local crate.
+{{/option}}
+
 {{> options-registry }}
 
 {{/options}}

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

@@ -5,7 +5,7 @@ NAME
 
 SYNOPSIS
        cargo add [options] crate…
-       cargo add [options] --path path
+       cargo add [options] --path path [--base base]
        cargo add [options] --git url [crate…]
 
 DESCRIPTION
@@ -56,6 +56,11 @@ OPTIONS
            <https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html#specifying-path-dependencies>
            to local crate to add.
 
+       --base base
+           The path base
+           <https://doc.rust-lang.org/cargo/reference/unstable.html#path-bases>
+           to use when adding a local crate.
+
        --registry registry
            Name of the registry to use. Registry names are defined in Cargo
            config files

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

@@ -6,7 +6,7 @@ cargo-add --- Add dependencies to a Cargo.toml manifest file
 ## SYNOPSIS
 
 `cargo add` [_options_] _crate_...\
-`cargo add` [_options_] `--path` _path_\
+`cargo add` [_options_] `--path` _path_ [`--base` _base_]\
 `cargo add` [_options_] `--git` _url_ [_crate_...]
 
 
@@ -59,6 +59,10 @@ dependency will be listed in the command's output.
 <dd class="option-desc"><a href="../reference/specifying-dependencies.html#specifying-path-dependencies">Filesystem path</a> to local crate to add.</dd>
 
 
+<dt class="option-term" id="option-cargo-add---base"><a class="option-anchor" href="#option-cargo-add---base"></a><code>--base</code> <em>base</em></dt>
+<dd class="option-desc">The <a href="../reference/unstable.html#path-bases">path base</a> to use when adding a local crate.</dd>
+
+
 <dt class="option-term" id="option-cargo-add---registry"><a class="option-anchor" href="#option-cargo-add---registry"></a><code>--registry</code> <em>registry</em></dt>
 <dd class="option-desc">Name of the registry to use. Registry names are defined in <a href="../reference/config.html">Cargo config
 files</a>. If not specified, the default registry is used,

src/etc/man/cargo-add.1

@@ -8,7 +8,7 @@ cargo\-add \[em] Add dependencies to a Cargo.toml manifest file
 .SH "SYNOPSIS"
 \fBcargo add\fR [\fIoptions\fR] \fIcrate\fR\[u2026]
 .br
-\fBcargo add\fR [\fIoptions\fR] \fB\-\-path\fR \fIpath\fR
+\fBcargo add\fR [\fIoptions\fR] \fB\-\-path\fR \fIpath\fR [\fB\-\-base\fR \fIbase\fR]
 .br
 \fBcargo add\fR [\fIoptions\fR] \fB\-\-git\fR \fIurl\fR [\fIcrate\fR\[u2026]]
 .SH "DESCRIPTION"
@@ -74,6 +74,11 @@ Specific commit to use when adding from git.
 \fIFilesystem path\fR <https://doc.rust\-lang.org/cargo/reference/specifying\-dependencies.html#specifying\-path\-dependencies> to local crate to add.
 .RE
 .sp
+\fB\-\-base\fR \fIbase\fR
+.RS 4
+The \fIpath base\fR <https://doc.rust\-lang.org/cargo/reference/unstable.html#path\-bases> to use when adding a local crate.
+.RE
+.sp
 \fB\-\-registry\fR \fIregistry\fR
 .RS 4
 Name of the registry to use. Registry names are defined in \fICargo config