[StGit PATCH] Print conflict details with the new infrastructure (bug #11181)

[Catalin Marinas <catalin.marinas@gmail.com>]

The patch modifies the IndexAndWorkTree.merge() function to display
pass the conflict information (files) when raising an exception. The
logic is similar to the one in the old infrastructure.

Signed-off-by: Catalin Marinas <catalin.marinas@gmail.com>
---
 stgit/lib/git.py         |   15 ++++++++++-----
 stgit/lib/transaction.py |   11 ++++++++---
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/stgit/lib/git.py b/stgit/lib/git.py
index 0a208ef..e2b4266 100644
--- a/stgit/lib/git.py
+++ b/stgit/lib/git.py
@@ -677,6 +677,9 @@ class MergeException(exception.StgException):
 
 class MergeConflictException(MergeException):
     """Exception raised when a merge fails due to conflicts."""
+    def __init__(self, conflicts):
+        MergeException.__init__(self)
+        self.conflicts = conflicts
 
 class Index(RunWithEnv):
     """Represents a git index file."""
@@ -829,12 +832,14 @@ class IndexAndWorktree(RunWithEnvCwd):
                          env = { 'GITHEAD_%s' % base.sha1: 'ancestor',
                                  'GITHEAD_%s' % ours.sha1: 'current',
                                  'GITHEAD_%s' % theirs.sha1: 'patched'})
-            r.discard_output()
+            r.returns([0, 1])
+            output = r.output_lines()
+            if r.exitcode:
+                # There were conflicts
+                conflicts = [l for l in output if l.startswith('CONFLICT')]
+                raise MergeConflictException(conflicts)
         except run.RunException, e:
-            if r.exitcode == 1:
-                raise MergeConflictException()
-            else:
-                raise MergeException('Index/worktree dirty')
+            raise MergeException('Index/worktree dirty')
     def changed_files(self, tree, pathlimits = []):
         """Return the set of files in the worktree that have changed with
         respect to C{tree}. The listing is optionally restricted to
diff --git a/stgit/lib/transaction.py b/stgit/lib/transaction.py
index 0f414d8..54de127 100644
--- a/stgit/lib/transaction.py
+++ b/stgit/lib/transaction.py
@@ -94,6 +94,7 @@ class StackTransaction(object):
         self.__base = self.__stack.base
         self.__discard_changes = discard_changes
         self.__bad_head = None
+        self.__conflicts = None
         if isinstance(allow_conflicts, bool):
             self.__allow_conflicts = lambda trans: allow_conflicts
         else:
@@ -201,7 +202,10 @@ class StackTransaction(object):
             self.__stack.set_head(new_head, self.__msg)
 
         if self.__error:
-            out.error(self.__error)
+            if self.__conflicts:
+                out.error(*([self.__error] + self.__conflicts))
+            else:
+                out.error(self.__error)
 
         # Write patches.
         def write(msg):
@@ -311,9 +315,10 @@ class StackTransaction(object):
                 tree = iw.index.write_tree()
                 self.__current_tree = tree
                 s = ' (modified)'
-            except git.MergeConflictException:
+            except git.MergeConflictException, e:
                 tree = ours
                 merge_conflict = True
+                self.__conflicts = e.conflicts
                 s = ' (conflict)'
             except git.MergeException, e:
                 self.__halt(str(e))
@@ -344,7 +349,7 @@ class StackTransaction(object):
 
             # Save this update so that we can run it a little later.
             self.__conflicting_push = update
-            self.__halt('Merge conflict')
+            self.__halt("%d merge conflict(s)" % len(self.__conflicts))
         else:
             # Update immediately.
             update()