git-review-rebase: also flag changes in commit descriptions.

This just adds yet another marker, this time to show when there are changes
to the commit description, which would otherwise not show if the patch-id
are strictly equivalent.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@vates.tech>

Author: casasnovas

scripts/git-review-rebase/README.md

@@ -20,10 +20,15 @@ An interactive TUI (Terminal User Interface) tool for reviewing rebased git bran
   | ---- | ----------------------------------------- |
   | `=`  | Same commit (identical SHA1               |
   | `~`  | Loose match (same title, patchid changed) |
+  | `✎`  | Commit message changed                    |
   | `⤶`  | Already present in new upstream           |
   | `✗`  | Dropped during rebase                     |
   | `✚`  | Added in rebase                           |
 
+> A commit message comparison ignores trailing whitespace and surrounding blank lines, so `✎`
+> only shows up when the message content itself differs. It is never set on `=` matches, since
+> those commits are identical by definition.
+
 > **Patchid** is a checksum of a commit's diff (`git patch-id`). Two commits with different
 > SHA1 (e.g. after rebase) that introduce the same code changes will have the same patchid.
 > This allows the tool to match commits across a rebase even when their SHA-1s change.

scripts/git-review-rebase/src/git_review_rebase/commit_matching.py

@@ -6,7 +6,7 @@
 
 from .branch_range import BranchRange
 from .constants import CommitMatchInfoFlag
-from .git_utils import abbrev, commit_title
+from .git_utils import abbrev, commit_title, message_changed
 
 
 class RebasedCommitMatch:
@@ -67,6 +67,13 @@ def init_matches(self) -> None:
                 if right_commit is not None:
                     match_info = CommitMatchInfoFlag.LooseMatch
 
+            if (
+                right_commit is not None
+                and right_commit.id != left_commit.id
+                and message_changed(left_commit, right_commit)
+            ):
+                match_info |= CommitMatchInfoFlag.MessageChanged
+
             if (
                 right_commit is not None
                 and right_commit.id not in self.right_range._rebased_commits

scripts/git-review-rebase/src/git_review_rebase/constants.py

@@ -28,6 +28,7 @@ class SolarizedColors(StrEnum):
 class CommitMatchInfoFlag(Flag):
     SameCommit = auto()
     LooseMatch = auto()
+    MessageChanged = auto()
     PresentInRebaseOnto = auto()
     Dropped = auto()
     Added = auto()
@@ -49,6 +50,11 @@ def __init__(self, flag, character, definition):
         Text("~", SolarizedColors.Yellow),
         "Commit patchid has changed",
     ),
+    CommitMatchInfoFlag.MessageChanged: CommitMatchInfo(
+        CommitMatchInfoFlag.MessageChanged,
+        Text("✎", SolarizedColors.Orange),
+        "Commit message has changed",
+    ),
     CommitMatchInfoFlag.PresentInRebaseOnto: CommitMatchInfo(
         CommitMatchInfoFlag.PresentInRebaseOnto,
         Text("⤶", SolarizedColors.Blue),

scripts/git-review-rebase/src/git_review_rebase/git_utils.py

@@ -40,6 +40,16 @@ def commit_title(commit: pygit2.Commit) -> str:
     return (commit.message.splitlines() or [""])[0]
 
 
+def normalized_message(commit: pygit2.Commit) -> str:
+    """Commit message without trailing whitespace nor surrounding blank lines."""
+    return "\n".join(line.rstrip() for line in commit.message.strip().splitlines())
+
+
+def message_changed(left_commit: pygit2.Commit, right_commit: pygit2.Commit) -> bool:
+    """Return True if both commits do not share the same message."""
+    return normalized_message(left_commit) != normalized_message(right_commit)
+
+
 def cached_patchid_ref(revision: str) -> str:
     """Poor man's cache in git refs directly using merkle trees."""
     return f"refs/patchids/from_revision/" f"{revision[:2]}/{revision[2:4]}/{revision[4:]}"