Deduplicate external contracts by full path (#2001)

fixes #2003

- **Add failing test case**
- **Deduplicate external contracts by full path**

Author: maciektr

scarb/src/compiler/compilers/starknet_contract/compiler.rs

@@ -332,9 +332,18 @@ pub fn find_project_contracts(
         Vec::new()
     };
 
-    Ok(internal_contracts
+    // Deduplicate found contracts by contract path.
+    let mut contracts_found = internal_contracts
         .into_iter()
         .chain(external_contracts)
+        .map(|decl| (decl.module_id().full_path(db.upcast()), decl))
+        .sorted_by_key(|(path, _)| path.clone())
+        .collect_vec();
+    contracts_found.dedup_by_key(|(path, _)| path.clone());
+
+    Ok(contracts_found
+        .into_iter()
+        .map(|(_path, decl)| decl)
         .collect())
 }
 

scarb/tests/build_starknet_external_contracts.rs

@@ -558,3 +558,54 @@ fn can_build_external_reexported_contracts() {
         ]
     );
 }
+#[test]
+fn can_dedup_contract_reexports() {
+    let t = TempDir::new().unwrap();
+    let hello = t.child("hello");
+    let world = t.child("world");
+
+    ProjectBuilder::start()
+        .name("hello")
+        .version("0.1.0")
+        .manifest_extra(indoc! {r#"
+            [lib]
+            [[target.starknet-contract]]
+        "#})
+        .dep_starknet()
+        .lib_cairo(indoc! {r#"
+            // Note that Balance contract can be accessed both through mod tree and the reexport.
+            pub mod a; 
+            pub use a::Balance;
+        "#})
+        .src("src/a.cairo", BALANCE_CONTRACT)
+        .build(&hello);
+
+    ProjectBuilder::start()
+        .name("world")
+        .version("0.1.0")
+        .dep("hello", hello)
+        .manifest_extra(formatdoc! {r#"
+            [[target.starknet-contract]]
+            build-external-contracts = ["hello::*"]
+        "#})
+        .dep_starknet()
+        .build(&world);
+
+    Scarb::quick_snapbox()
+        .arg("build")
+        .current_dir(&world)
+        .assert()
+        .success()
+        .stdout_matches(indoc! {r#"
+        [..] Compiling world v0.1.0 ([..]/Scarb.toml)
+        [..]  Finished `dev` profile target(s) in [..]
+    "#});
+
+    assert_eq!(
+        world.child("target/dev").files(),
+        vec![
+            "world.starknet_artifacts.json",
+            "world_Balance.contract_class.json",
+        ]
+    );
+}