Don't error on no binaries installed

If we interpret `cargo install` and `cargo install --bins` as "install
the binaries that are available", it should not be considered an error
if no binaries ended up being installed due to required features.
Instead, this should provide the user with a warning that this may not
have been what they intended.

Fixes #10289.

Author: Jon Gjengset

src/cargo/ops/cargo_install.rs

@@ -5,7 +5,8 @@ use std::{env, fs};
 
 use crate::core::compiler::{CompileKind, DefaultExecutor, Executor, Freshness, UnitOutput};
 use crate::core::{Dependency, Edition, Package, PackageId, Source, SourceId, Workspace};
-use crate::ops::common_for_install_and_uninstall::*;
+use crate::ops::CompileFilter;
+use crate::ops::{common_for_install_and_uninstall::*, FilterRule};
 use crate::sources::{GitSource, PathSource, SourceConfigMap};
 use crate::util::errors::CargoResult;
 use crate::util::{Config, Filesystem, Rustc, ToSemver, VersionReqExt};
@@ -272,7 +273,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
         Ok(duplicates)
     }
 
-    fn install_one(mut self) -> CargoResult<()> {
+    fn install_one(mut self) -> CargoResult<bool> {
         self.config.shell().status("Installing", &self.pkg)?;
 
         let dst = self.root.join("bin").into_path_unlocked();
@@ -322,7 +323,41 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
             })
             .collect::<CargoResult<_>>()?;
         if binaries.is_empty() {
-            bail!("no binaries are available for install using the selected features");
+            // Cargo already warns the user if they use a target specifier that matches nothing,
+            // but we want to error if the user asked for a _particular_ binary to be installed,
+            // and we didn't end up installing it.
+            //
+            // NOTE: This _should_ be impossible to hit since --bin=does_not_exist will fail on
+            // target selection, and --bin=requires_a without --features=a will fail with "target
+            // .. requires the features ..". But rather than assume that's the case, we define the
+            // behavior for this fallback case as well.
+            if matches!(
+                self.opts.filter,
+                CompileFilter::Only {
+                    bins: FilterRule::Just(..),
+                    ..
+                }
+            ) {
+                bail!("no binaries are available for install using the selected features");
+            }
+
+            // If the user did not specify a filter and there _are_ binaries available, but none
+            // were selected given the current set of features, let the user know.
+            if matches!(
+                self.opts.filter,
+                CompileFilter::Default { .. }
+                    | CompileFilter::Only {
+                        bins: FilterRule::All,
+                        ..
+                    }
+            ) && self.pkg.targets().iter().any(|t| t.is_bin())
+            {
+                self.config
+                    .shell()
+                    .warn("none of the package's binaries are available for install using the selected features")?;
+            }
+
+            return Ok(false);
         }
         // This is primarily to make testing easier.
         binaries.sort_unstable();
@@ -455,7 +490,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
                     executables(successful_bins.iter())
                 ),
             )?;
-            Ok(())
+            Ok(true)
         } else {
             if !to_install.is_empty() {
                 self.config.shell().status(
@@ -481,7 +516,7 @@ impl<'cfg, 'a> InstallablePackage<'cfg, 'a> {
                     ),
                 )?;
             }
-            Ok(())
+            Ok(true)
         }
     }
 
@@ -545,10 +580,11 @@ pub fn install(
             no_track,
             true,
         )?;
+        let mut installed_anything = true;
         if let Some(installable_pkg) = installable_pkg {
-            installable_pkg.install_one()?;
+            installed_anything = installable_pkg.install_one()?;
         }
-        (true, false)
+        (installed_anything, false)
     } else {
         let mut succeeded = vec![];
         let mut failed = vec![];
@@ -601,8 +637,10 @@ pub fn install(
 
         for (krate, result) in install_results {
             match result {
-                Ok(()) => {
-                    succeeded.push(krate);
+                Ok(installed) => {
+                    if installed {
+                        succeeded.push(krate);
+                    }
                 }
                 Err(e) => {
                     crate::display_error(&e, &mut config.shell());

tests/testsuite/required_features.rs

@@ -650,12 +650,11 @@ fn install_default_features() {
     p.cargo("uninstall foo").run();
 
     p.cargo("install --path . --no-default-features")
-        .with_status(101)
         .with_stderr(
             "\
 [INSTALLING] foo v0.0.1 ([..])
 [FINISHED] release [optimized] target(s) in [..]
-[ERROR] no binaries are available for install using the selected features
+[WARNING] none of the package's binaries are available for install using the selected features
 ",
         )
         .run();
@@ -772,12 +771,11 @@ fn install_multiple_required_features() {
     p.cargo("uninstall foo").run();
 
     p.cargo("install --path . --no-default-features")
-        .with_status(101)
         .with_stderr(
             "\
 [INSTALLING] foo v0.0.1 ([..])
 [FINISHED] release [optimized] target(s) in [..]
-[ERROR] no binaries are available for install using the selected features
+[WARNING] none of the package's binaries are available for install using the selected features
 ",
         )
         .run();
@@ -1029,12 +1027,11 @@ Consider enabling them by passing, e.g., `--features=\"bar/a\"`
 
     // install
     p.cargo("install --path .")
-        .with_status(101)
         .with_stderr(
             "\
 [INSTALLING] foo v0.0.1 ([..])
 [FINISHED] release [optimized] target(s) in [..]
-[ERROR] no binaries are available for install using the selected features
+[WARNING] none of the package's binaries are available for install using the selected features
 ",
         )
         .run();