patch: fix patch hunk/metdata synchronization (issue3384)...
patch: fix patch hunk/metdata synchronization (issue3384)
Git patches are parsed in two phases: 1) extract metadata, 2) parse actual
deltas and merge them with the previous metadata. We do this to avoid
dependency issues like "modify a; copy a to b", where "b" must be copied from
the unmodified "a".
Issue3384 is caused by flaky code I wrote to synchronize the patch metadata
with the emitted hunk:
if (gitpatches and
(gitpatches[-1][0] == afile or gitpatches[-1][1] == bfile)):
gp = gitpatches.pop()[2]
With a patch like:
diff --git a/a b/c
copy from a
copy to c
--- a/a
+++ b/c
@@ -1,1 +1,2 @@
a
+a
@@ -2,1 +2,2 @@
a
+a
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,1 +1,2 @@
a
+b
the first hunk of the first block is matched with the metadata for the block
"diff --git a/a b/c", then the second hunk of the first block is matched with
the metadata of the second block "diff --git a/a b/a", because of the "or" in
the code paste above. Turning the "or" into an "and" is not enough as we have
to deal with /dev/null cases for each file.
We I remove this broken piece of code:
# copy/rename + modify should modify target, not source
if gp.op in ('COPY', 'DELETE', 'RENAME', 'ADD') or gp.mode:
afile = bfile
because "afile = bfile" set "afile" to stuff like "b/file" instead of "a/file",
and because this only happens for git patches, which afile/bfile are ignored
anyway by applydiff().
v2:
- Avoid a traceback on git metadata desynchronization
