Ignore workspace.default-members when running cargo install on root package of a non-virtual workspace

src/cargo/core/compiler/build_config.rs

@@ -6,10 +6,11 @@ use cargo_util::ProcessBuilder;
 use serde::ser;
 use std::cell::RefCell;
 use std::path::PathBuf;
+use std::sync::Arc;
 use std::thread::available_parallelism;
 
 /// Configuration information for a rustc build.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct BuildConfig {
     /// The requested kind of compilation for this session
     pub requested_kinds: Vec<CompileKind>,
@@ -33,7 +34,7 @@ pub struct BuildConfig {
     pub primary_unit_rustc: Option<ProcessBuilder>,
     /// A thread used by `cargo fix` to receive messages on a socket regarding
     /// the success/failure of applying fixes.
-    pub rustfix_diagnostic_server: RefCell<Option<RustfixDiagnosticServer>>,
+    pub rustfix_diagnostic_server: Arc<RefCell<Option<RustfixDiagnosticServer>>>,
     /// The directory to copy final artifacts to. Note that even if `out_dir` is
     /// set, a copy of artifacts still could be found a `target/(debug\release)`
     /// as usual.
@@ -100,7 +101,7 @@ impl BuildConfig {
             build_plan: false,
             unit_graph: false,
             primary_unit_rustc: None,
-            rustfix_diagnostic_server: RefCell::new(None),
+            rustfix_diagnostic_server: Arc::new(RefCell::new(None)),
             export_dir: None,
             future_incompat_report: false,
             timing_outputs: Vec::new(),

src/cargo/ops/cargo_compile/compile_filter.rs

@@ -34,7 +34,7 @@ pub enum FilterRule {
 ///
 /// [`generate_root_units`]: super::UnitGenerator::generate_root_units
 /// [`Packages`]: crate::ops::Packages
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum CompileFilter {
     /// The default set of Cargo targets.
     Default {

src/cargo/ops/cargo_compile/mod.rs

@@ -68,7 +68,7 @@ pub use packages::Packages;
 /// of it as `CompileOptions` are high-level settings requested on the
 /// command-line, and `BuildConfig` are low-level settings for actually
 /// driving `rustc`.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct CompileOptions {
     /// Configuration information for a rustc build
     pub build_config: BuildConfig,

src/cargo/ops/cargo_compile/packages.rs

@@ -13,7 +13,7 @@ use anyhow::{bail, Context as _};
 ///
 /// Generally, it represents the combination of all `-p` flag. When working within
 /// a workspace, `--exclude` and `--workspace` flags also contribute to it.
-#[derive(PartialEq, Eq, Debug)]
+#[derive(PartialEq, Eq, Debug, Clone)]
 pub enum Packages {
     /// Packages selected by default. Usually means no flag provided.
     Default,

src/cargo/ops/cargo_install.rs

@@ -5,8 +5,8 @@ use std::{env, fs};
 
 use crate::core::compiler::{CompileKind, DefaultExecutor, Executor, UnitOutput};
 use crate::core::{Dependency, Edition, Package, PackageId, Source, SourceId, Workspace};
-use crate::ops::CompileFilter;
 use crate::ops::{common_for_install_and_uninstall::*, FilterRule};
+use crate::ops::{CompileFilter, Packages};
 use crate::sources::{GitSource, PathSource, SourceConfigMap};
 use crate::util::errors::CargoResult;
 use crate::util::{Config, Filesystem, Rustc, ToSemver, VersionReqExt};
@@ -37,7 +37,7 @@ impl Drop for Transaction {
 
 struct InstallablePackage<'cfg, 'a> {
     config: &'cfg Config,
-    opts: &'a ops::CompileOptions,
+    opts: ops::CompileOptions,
     root: Filesystem,
     source_id: SourceId,
     vers: Option<&'a str>,
@@ -60,7 +60,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
         source_id: SourceId,
         from_cwd: bool,
         vers: Option<&'a str>,
-        opts: &'a ops::CompileOptions,
+        original_opts: &'a ops::CompileOptions,
         force: bool,
         no_track: bool,
         needs_update_if_source_is_index: bool,
@@ -145,7 +145,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
                     dep.clone(),
                     &mut source,
                     config,
-                    opts,
+                    original_opts,
                     &root,
                     &dst,
                     force,
@@ -167,7 +167,14 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
             }
         };
 
-        let (ws, rustc, target) = make_ws_rustc_target(config, opts, &source_id, pkg.clone())?;
+        // When we build this package, we want to build the *specified* package only,
+        // and avoid building e.g. workspace default-members instead. Do so by constructing
+        // specialized compile options specific to the identified package.
+        // See test `path_install_workspace_root_despite_default_members`.
+        let mut opts = original_opts.clone();
+        opts.spec = Packages::Packages(vec![pkg.name().to_string()]);
+
+        let (ws, rustc, target) = make_ws_rustc_target(config, &opts, &source_id, pkg.clone())?;
         // If we're installing in --locked mode and there's no `Cargo.lock` published
         // ie. the bin was published before https://github.com/rust-lang/cargo/pull/7026
         if config.locked() && !ws.root().join("Cargo.lock").exists() {
@@ -235,7 +242,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
             // Check for conflicts.
             ip.no_track_duplicates(&dst)?;
         } else if is_installed(
-            &ip.pkg, config, opts, &ip.rustc, &ip.target, &ip.root, &dst, force,
+            &ip.pkg, config, &ip.opts, &ip.rustc, &ip.target, &ip.root, &dst, force,
         )? {
             let msg = format!(
                 "package `{}` is already installed, use --force to override",
@@ -297,7 +304,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
         self.check_yanked_install()?;
 
         let exec: Arc<dyn Executor> = Arc::new(DefaultExecutor);
-        let compile = ops::compile_ws(&self.ws, self.opts, &exec).with_context(|| {
+        let compile = ops::compile_ws(&self.ws, &self.opts, &exec).with_context(|| {
             if let Some(td) = td_opt.take() {
                 // preserve the temporary directory, so the user can inspect it
                 td.into_path();
@@ -372,7 +379,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
                 &dst,
                 &self.pkg,
                 self.force,
-                self.opts,
+                &self.opts,
                 &self.target,
                 &self.rustc.verbose_version,
             )?;
@@ -439,7 +446,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
                 &self.pkg,
                 &successful_bins,
                 self.vers.map(|s| s.to_string()),
-                self.opts,
+                &self.opts,
                 &self.target,
                 &self.rustc.verbose_version,
             );

tests/testsuite/install.rs

@@ -1292,6 +1292,46 @@ fn use_path_workspace() {
     assert_eq!(lock, lock2, "different lockfiles");
 }
 
+#[cargo_test]
+fn path_install_workspace_root_despite_default_members() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "ws-root"
+                version = "0.1.0"
+                authors = []
+
+                [workspace]
+                members = ["ws-member"]
+                default-members = ["ws-member"]
+            "#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .file(
+            "ws-member/Cargo.toml",
+            r#"
+                [package]
+                name = "ws-member"
+                version = "0.1.0"
+                authors = []
+            "#,
+        )
+        .file("ws-member/src/main.rs", "fn main() {}")
+        .build();
+
+    p.cargo("install --path")
+        .arg(p.root())
+        .arg("ws-root")
+        .with_stderr_contains(
+            "[INSTALLED] package `ws-root v0.1.0 ([..])` (executable `ws-root[EXE]`)",
+        )
+        // Particularly avoid "Installed package `ws-root v0.1.0 ([..]])` (executable `ws-member`)":
+        .with_stderr_does_not_contain("ws-member")
+        .run();
+}
+
 #[cargo_test]
 fn dev_dependencies_no_check() {
     Package::new("foo", "1.0.0").publish();