Add suggestions when cargo add multiple packages

src/cargo/ops/cargo_add/mod.rs

@@ -289,7 +289,7 @@ fn resolve_dependency(
         } else {
             let mut source = crate::sources::GitSource::new(src.source_id()?, config)?;
             let packages = source.read_packages()?;
-            let package = infer_package(packages, &src)?;
+            let package = infer_package_for_git_source(packages, &src)?;
             Dependency::from(package.summary())
         };
         selected
@@ -313,8 +313,7 @@ fn resolve_dependency(
             selected
         } else {
             let source = crate::sources::PathSource::new(&path, src.source_id()?, config);
-            let packages = source.read_packages()?;
-            let package = infer_package(packages, &src)?;
+            let package = source.read_packages()?.pop().expect("at least one package");
             Dependency::from(package.summary())
         };
         selected
@@ -599,19 +598,32 @@ fn select_package(
     }
 }
 
-fn infer_package(mut packages: Vec<Package>, src: &dyn std::fmt::Display) -> CargoResult<Package> {
+fn infer_package_for_git_source(
+    mut packages: Vec<Package>,
+    src: &dyn std::fmt::Display,
+) -> CargoResult<Package> {
     let package = match packages.len() {
-        0 => {
-            anyhow::bail!("no packages found at `{src}`");
-        }
+        0 => unreachable!(),
         1 => packages.pop().expect("match ensured element is present"),
         _ => {
             let mut names: Vec<_> = packages
                 .iter()
                 .map(|p| p.name().as_str().to_owned())
                 .collect();
             names.sort_unstable();
-            anyhow::bail!("multiple packages found at `{src}`: {}", names.join(", "));
+            anyhow::bail!(
+                "multiple packages found at `{src}`:\n    {}\nTo disambiguate, run `cargo add --git {src} <package>`",
+                names
+                    .iter()
+                    .map(|s| s.to_string())
+                    .coalesce(|x, y| if x.len() + y.len() < 78 {
+                        Ok(format!("{x}, {y}"))
+                    } else {
+                        Err((x, y))
+                    })
+                    .into_iter()
+                    .format("\n    "),
+            );
         }
     };
     Ok(package)

tests/testsuite/cargo_add/git_inferred_name_multiple/mod.rs

@@ -23,6 +23,41 @@ fn git_inferred_name_multiple() {
                 &cargo_test_support::basic_manifest("my-package2", "0.3.0+my-package2"),
             )
             .file("p2/src/lib.rs", "")
+            .file(
+                "p3/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package3", "0.3.0+my-package2"),
+            )
+            .file("p3/src/lib.rs", "")
+            .file(
+                "p4/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package4", "0.3.0+my-package2"),
+            )
+            .file("p4/src/lib.rs", "")
+            .file(
+                "p5/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package5", "0.3.0+my-package2"),
+            )
+            .file("p5/src/lib.rs", "")
+            .file(
+                "p6/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package6", "0.3.0+my-package2"),
+            )
+            .file("p6/src/lib.rs", "")
+            .file(
+                "p7/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package7", "0.3.0+my-package2"),
+            )
+            .file("p7/src/lib.rs", "")
+            .file(
+                "p8/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package8", "0.3.0+my-package2"),
+            )
+            .file("p8/src/lib.rs", "")
+            .file(
+                "p9/Cargo.toml",
+                &cargo_test_support::basic_manifest("my-package9", "0.3.0+my-package2"),
+            )
+            .file("p9/src/lib.rs", "")
     });
     let git_url = git_dep.url().to_string();
 

tests/testsuite/cargo_add/git_inferred_name_multiple/stderr.log

@@ -1,2 +1,5 @@
     Updating git repository `[ROOTURL]/git-package`
-error: multiple packages found at `[ROOTURL]/git-package`: my-package1, my-package2
+error: multiple packages found at `[ROOTURL]/git-package`:
+    my-package1, my-package2, my-package3, my-package4, my-package5, my-package6
+    my-package7, my-package8, my-package9
+To disambiguate, run `cargo add --git [ROOTURL]/git-package <package>`