# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1601411888 -7200
# Node ID f6811e5bd994e532d4d507e166083c2d5ef18343
# Parent  308ca5528ee6357f564ed2a1b052677706409186
changing-files: add clean computation of changed files for roots

The `files` field is not reliable, so we need to compute things from scratch. We
start with the simplest case root changesets. In the beginning they was nothing,
then user said "let there be files" and there were added files.

Differential Revision: https://phab.mercurial-scm.org/D9126

diff -r 308ca5528ee6 -r f6811e5bd994 mercurial/metadata.py
--- a/mercurial/metadata.py	Wed Sep 30 09:21:33 2020 +0200
+++ b/mercurial/metadata.py	Tue Sep 29 22:38:08 2020 +0200
@@ -226,6 +226,10 @@
 
 def compute_all_files_changes(ctx):
     """compute the files changed by a revision"""
+    p1 = ctx.p1()
+    p2 = ctx.p2()
+    if p1.rev() == node.nullrev and p2.rev() == node.nullrev:
+        return _process_root(ctx)
     filescopies = computechangesetcopies(ctx)
     filesadded = computechangesetfilesadded(ctx)
     filesremoved = computechangesetfilesremoved(ctx)
@@ -240,6 +244,17 @@
     return files
 
 
+def _process_root(ctx):
+    """compute the appropriate changed files for a changeset with no parents
+    """
+    # Simple, there was nothing before it, so everything is added.
+    md = ChangingFiles()
+    manifest = ctx.manifest()
+    for filename in manifest:
+        md.mark_added(filename)
+    return md
+
+
 def computechangesetfilesadded(ctx):
     """return the list of files added in a changeset
     """