Add a "default" SolveGroup to the default Environment (if not redefined)

docs/configuration.md

@@ -564,6 +564,13 @@ prod = {features = ["prod"], solve-group = "test"}
 lint = ["lint"]
 ```
 
+Unless the `default` environment is redefined, it is included in the `default` solve group. That is, the following is implied unless overridden in the manifest's `[environments]` table:
+```toml title="default environment"
+[environments]
+default = { features = [], solve-group = "default" } # the default environment includes the 'default' feature only
+```
+
+
 ## Global configuration
 
 The global configuration options are documented in the [global configuration](advanced/global_configuration.md) section.

src/cli/init.rs

@@ -68,7 +68,6 @@ platforms = {{ platforms }}
 {%- if loop.first %}
 
 [tool.pixi.environments]
-default = { features = [], solve-group = "default" }
 {%- endif %}
 {{env}} = { features = {{ features }}, solve-group = "default" }
 {%- endfor %}

src/project/manifest/mod.rs

@@ -750,6 +750,17 @@ impl SolveGroups {
     pub fn iter(&self) -> impl Iterator<Item = &SolveGroup> + '_ {
         self.solve_groups.iter()
     }
+
+    /// Inserts a SolveGroup based on a name and an environment index
+    pub fn insert(&mut self, name: &str, environment_idx: usize) -> usize {
+        let idx = self.solve_groups.len();
+        self.solve_groups.push(SolveGroup {
+            name: name.to_string(),
+            environments: vec![environment_idx],
+        });
+        self.by_name.insert(name.to_string(), idx);
+        idx
+    }
 }
 
 /// Describes the contents of a project manifest.
@@ -1022,7 +1033,7 @@ impl<'de> Deserialize<'de> for ProjectManifest {
                 name: EnvironmentName::Default,
                 features: Vec::new(),
                 features_source_loc: None,
-                solve_group: None,
+                solve_group: Some(solve_groups.insert("default", 0)),
             });
             environments.by_name.insert(EnvironmentName::Default, 0);
         }
@@ -1049,15 +1060,7 @@ impl<'de> Deserialize<'de> for ProjectManifest {
                             .push(environment_idx);
                         *idx
                     }
-                    None => {
-                        let idx = solve_groups.solve_groups.len();
-                        solve_groups.solve_groups.push(SolveGroup {
-                            name: solve_group.clone(),
-                            environments: vec![environment_idx],
-                        });
-                        solve_groups.by_name.insert(solve_group, idx);
-                        idx
-                    }
+                    None => solve_groups.insert(&solve_group, environment_idx),
                 })
             } else {
                 None

src/project/solve_group.rs

@@ -223,10 +223,10 @@ mod tests {
         let foo_environment = project.environment("foo").unwrap();
         let bar_environment = project.environment("bar").unwrap();
 
-        let solve_groups = project.solve_groups();
-        assert_eq!(solve_groups.len(), 1);
+        let solve_groups = project.solve_groups(); // contains 'default', 'group1'
+        assert_eq!(solve_groups.len(), 2);
 
-        let solve_group = solve_groups[0].clone();
+        let solve_group = solve_groups[1].clone(); // 'group1' solve group
         let solve_group_envs = solve_group.environments().collect_vec();
         assert_eq!(solve_group_envs.len(), 2);
         assert_eq!(solve_group_envs[0].name(), "foo");