feat(smartlog): Only HEAD and main should be mandatory in the smartlog

Interactive undo needs to display a lot more context, so its behavior is
preserved.

git-branchless/src/commands/smartlog.rs

@@ -26,7 +26,7 @@ use lib::core::node_descriptors::{
 };
 use lib::git::{ConfigRead, GitRunInfo, Repo};
 
-pub use graph::{make_smartlog_graph, SmartlogGraph};
+pub use graph::{make_custom_smartlog_graph, make_smartlog_graph, SmartLogKind, SmartlogGraph};
 pub use render::{render_graph, SmartlogOptions};
 
 use crate::opts::Revset;
@@ -216,7 +216,18 @@ mod graph {
         }
     }
 
-    /// Construct the smartlog graph for the repo.
+    /// What kind of smartlog is desired?
+    #[derive(Debug)]
+    pub enum SmartLogKind {
+        /// The default smartlog, with all draft commits visible.
+        Default,
+
+        /// A smartlog representing only a specific set of a commits, such when
+        /// a user calls `smartlog` and specifies a revset .
+        Specific,
+    }
+
+    /// Construct the default smartlog graph for the repo.
     #[instrument]
     pub fn make_smartlog_graph<'repo>(
         effects: &Effects,
@@ -226,6 +237,30 @@ mod graph {
         event_cursor: EventCursor,
         observed_commits: &CommitSet,
         remove_commits: bool,
+    ) -> eyre::Result<SmartlogGraph<'repo>> {
+        make_custom_smartlog_graph(
+            effects,
+            repo,
+            dag,
+            event_replayer,
+            event_cursor,
+            observed_commits,
+            remove_commits,
+            SmartLogKind::Default,
+        )
+    }
+
+    /// Construct a specific kind of smartlog graph for the repo.
+    #[instrument]
+    pub fn make_custom_smartlog_graph<'repo>(
+        effects: &Effects,
+        repo: &'repo Repo,
+        dag: &Dag,
+        event_replayer: &EventReplayer,
+        event_cursor: EventCursor,
+        observed_commits: &CommitSet,
+        remove_commits: bool,
+        smartlog_kind: SmartLogKind,
     ) -> eyre::Result<SmartlogGraph<'repo>> {
         let (effects, _progress) = effects.start_operation(OperationType::MakeGraph);
 
@@ -240,12 +275,23 @@ mod graph {
                 observed_commits.clone()
             };
 
-            let active_heads = dag.query_active_heads(&public_commits, &observed_commits)?;
-            for oid in commit_set_to_vec(&active_heads)? {
+            let observed_commits = match smartlog_kind {
+                SmartLogKind::Default => dag
+                    .query_active_heads(&public_commits, &observed_commits)?
+                    .union(&observed_commits),
+                SmartLogKind::Specific => {
+                    // The only 2 commits that *must* be displayed are HEAD and
+                    // main/master head.
+                    observed_commits
+                        .union(&dag.head_commit)
+                        .union(&dag.main_branch_commit)
+                }
+            };
+            for oid in commit_set_to_vec(&observed_commits)? {
                 mark_commit_reachable(repo, oid)?;
             }
 
-            walk_from_active_heads(&effects, repo, dag, &public_commits, &active_heads)?
+            walk_from_active_heads(&effects, repo, dag, &public_commits, &observed_commits)?
         };
         sort_children(&mut graph);
         Ok(graph)
@@ -573,16 +619,18 @@ pub fn smartlog(
         &references_snapshot,
     )?;
 
-    let revset = match revset {
-        Some(revset) => revset.clone(),
+    let default_revset = Revset("draft()".to_string());
+    let (revset, smartlog_kind) = match revset {
+        Some(revset) if revset == &default_revset => (revset.clone(), SmartLogKind::Default),
+        Some(revset) => (revset.clone(), SmartLogKind::Specific),
         None => {
             // TODO add test for custom default revset
-            let custom_default: Option<String> = repo
+            let user_default: Option<String> = repo
                 .get_readonly_config()?
                 .get("branchless.revsets.default")?;
-            match custom_default {
-                Some(custom_default) => Revset(custom_default),
-                None => Revset("draft()".to_string()),
+            match user_default {
+                Some(user_default) => (Revset(user_default), SmartLogKind::Specific),
+                None => (default_revset, SmartLogKind::Default),
             }
         }
     };
@@ -616,14 +664,15 @@ pub fn smartlog(
         observed_commits
     };
 
-    let graph = make_smartlog_graph(
+    let graph = make_custom_smartlog_graph(
         effects,
         &repo,
         &dag,
         &event_replayer,
         event_cursor,
         &observed_commits,
         !show_hidden_commits,
+        smartlog_kind,
     )?;
 
     let lines = render_graph(

git-branchless/src/opts.rs

@@ -8,7 +8,7 @@ use std::str::FromStr;
 
 /// A revset expression. Can be a commit hash, branch name, or one of the
 /// various revset functions.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Revset(pub String);
 
 impl FromStr for Revset {