chore: add the ability to specify a default member (#1926)

* first stage (no tests)

* add test

* fix typo

* add docs

* use `PathBuf` instead of `String`

crates/nargo/src/manifest/mod.rs

@@ -1,5 +1,5 @@
 use serde::Deserialize;
-use std::collections::BTreeMap;
+use std::{collections::BTreeMap, path::PathBuf};
 
 mod errors;
 pub use self::errors::InvalidPackageError;
@@ -53,8 +53,12 @@ pub struct Workspace {
 }
 
 #[derive(Default, Debug, Deserialize, Clone)]
+#[serde(rename_all = "kebab-case")]
 pub struct WorkspaceConfig {
-    pub members: Vec<String>,
+    /// List of members in this workspace.
+    pub members: Vec<PathBuf>,
+    /// Specifies the default crate to interact with in the context (similarly to how we have nargo as the default crate in this repository).
+    pub default_member: Option<PathBuf>,
 }
 
 #[allow(dead_code)]
@@ -107,3 +111,14 @@ fn parse_workspace_toml() {
 
     assert!(Manifest::from_toml_str(src).is_ok());
 }
+
+#[test]
+fn parse_workspace_default_member_toml() {
+    let src = r#"
+        [workspace]
+        members = ["a", "b"]
+        default-member = "a"
+    "#;
+
+    assert!(Manifest::from_toml_str(src).is_ok());
+}

crates/nargo_cli/src/resolver.rs

@@ -87,15 +87,22 @@ pub(crate) fn resolve_root_manifest(
             resolve_manifest(&mut context, crate_id, package, pkg_root)?;
         }
         Manifest::Workspace(workspace) => {
-            let members = workspace.config.members;
-            let root = match members.last() {
-                Some(member) => dir_path.join(member),
+            let config = workspace.config;
+            let members = config.members;
+
+            let maybe_local = config
+                .default_member
+                .or_else(|| members.last().cloned())
+                .map(|member| dir_path.join(member));
+
+            let default_member = match maybe_local {
+                Some(member) => member,
                 None => {
                     return Err(DependencyResolutionError::EmptyWorkspace { path: manifest_path })
                 }
             };
 
-            let (entry_path, _crate_type) = super::lib_or_bin(root)?;
+            let (entry_path, _crate_type) = super::lib_or_bin(default_member)?;
             let _local = create_local_crate(&mut context, entry_path, CrateType::Workspace);
 
             for member in members {

crates/nargo_cli/tests/test_data/workspace_default_member/Nargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+members = ["a"]
+default-member = "a"

crates/nargo_cli/tests/test_data/workspace_default_member/Prover.toml

@@ -0,0 +1,2 @@
+x = "1"
+y = "2"

crates/nargo_cli/tests/test_data/workspace_default_member/a/Nargo.toml

@@ -0,0 +1,5 @@
+[package]
+authors = [""]
+compiler_version = "0.8.0"
+
+[dependencies]

crates/nargo_cli/tests/test_data/workspace_default_member/a/src/main.nr

@@ -0,0 +1,11 @@
+fn main(x : Field, y : pub Field) {
+    assert(x != y);
+}
+
+#[test]
+fn test_main() {
+    main(1, 2);
+
+    // Uncomment to make test fail
+    // main(1, 1);
+}

crates/nargo_cli/tests/test_data_ssa_refactor/workspace_default_member/Nargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+members = ["a"]
+default-member = "a"

crates/nargo_cli/tests/test_data_ssa_refactor/workspace_default_member/Prover.toml

@@ -0,0 +1,2 @@
+x = "1"
+y = "2"

crates/nargo_cli/tests/test_data_ssa_refactor/workspace_default_member/a/Nargo.toml

@@ -0,0 +1,5 @@
+[package]
+authors = [""]
+compiler_version = "0.8.0"
+
+[dependencies]

crates/nargo_cli/tests/test_data_ssa_refactor/workspace_default_member/a/src/main.nr

@@ -0,0 +1,11 @@
+fn main(x : Field, y : pub Field) {
+    assert(x != y);
+}
+
+#[test]
+fn test_main() {
+    main(1, 2);
+
+    // Uncomment to make test fail
+    // main(1, 1);
+}

crates/noirc_frontend/src/hir/mod.rs

@@ -71,7 +71,10 @@ impl Context {
 
         // Check the crate type
         // We don't panic here to allow users to `evaluate` libraries which will do nothing
-        if self.crate_graph[*crate_id].crate_type == CrateType::Binary {
+        if matches!(
+            self.crate_graph[*crate_id].crate_type,
+            CrateType::Binary | CrateType::Workspace
+        ) {
             // All Binaries should have a main function
             local_crate.main_function()
         } else {