throwing an error when [lib] not specified in Scarb.toml

scarb/src/ops/package.rs

@@ -4,7 +4,7 @@ use std::io::{Seek, SeekFrom, Write};
 
 use anyhow::{bail, ensure, Context, Result};
 use camino::Utf8PathBuf;
-use indoc::writedoc;
+use indoc::{formatdoc, writedoc};
 
 use scarb_ui::components::Status;
 use scarb_ui::{HumanBytes, HumanCount};
@@ -156,6 +156,20 @@ fn list_one_impl(
 }
 
 fn prepare_archive_recipe(pkg: &Package) -> Result<ArchiveRecipe> {
+    ensure!(
+        pkg.manifest.targets.iter().any(|x| x.is_lib()),
+        formatdoc! {
+            r#"
+            package `{package_name}` does not provide a `[lib]` target.
+            if a package does not provide a library target, it cannot be used as a dependency.
+            help: add `[lib]` section to package manifest
+             --> Scarb.toml
+            +   [lib]
+            "#,
+            package_name=pkg.id.name,
+        }
+    );
+
     let mut recipe = source_files(pkg)?;
 
     // Sort the recipe before any checks, to ensure generated errors are reproducible.

scarb/tests/package.rs

@@ -837,3 +837,31 @@ fn ignore_whitelist_pattern() {
             src/lib.cairo
         "#}));
 }
+
+#[test]
+fn no_lib_target() {
+    let t = TempDir::new().unwrap();
+    let name = "foo";
+    let version = "1.0.0";
+    ProjectBuilder::start()
+        .name(name)
+        .version(version)
+        .manifest_extra(indoc! {r#"
+        [[target.starknet-contract]]
+        "#})
+        .build(&t);
+
+    Scarb::quick_snapbox()
+        .arg("package")
+        .current_dir(&t)
+        .assert()
+        .failure()
+        .stdout_matches(formatdoc! {r#"
+        [..] Packaging {name} v{version} [..]
+        error: package `{name}` does not provide a `[lib]` target.
+        if a package does not provide a library target, it cannot be used as a dependency.
+        help: add `[lib]` section to package manifest
+         --> Scarb.toml
+        +   [lib]
+        "#});
+}