annotate mercurial/help/revisions.txt @ 23871:b2d8f3685b06

dispatch: only check compatibility against major and minor versions (BC)

Extensions can declare compatibility with Mercurial versions. If an
error occurs, Mercurial will attempt to pin blame on an extension that
isn't marked as compatible.

While all bets are off when it comes to the internal API, my experience
has shown that a monthly/patch release of Mercurial has never broken any
of the extensions I've written. I think that expecting extensions to
declare compatibility with every patch release of Mercurial is asking a
bit much and adds little to no value.

This patch changes the blame logic from exact version matching to only
match on the major and minor Mercurial versions. This means that
extensions only need to mark themselves as compatible with the major,
quarterly releases and not the monthly ones in order to stay current and
avoid what is almost certainly unfair blame. This will mean less work
for extension authors and almost certainly fewer false positives in the
blame attribution.

Mercurial supports several ways to specify individual revisions.

A plain integer is treated as a revision number. Negative integers are
treated as sequential offsets from the tip, with -1 denoting the tip,
-2 denoting the revision prior to the tip, and so forth.

A 40-digit hexadecimal string is treated as a unique revision
identifier.

A hexadecimal string less than 40 characters long is treated as a
unique revision identifier and is referred to as a short-form
identifier. A short-form identifier is only valid if it is the prefix
of exactly one full-length identifier.

Any other string is treated as a bookmark, tag, or branch name. A
bookmark is a movable pointer to a revision. A tag is a permanent name
associated with a revision. A branch name denotes the tipmost open branch head
of that branch - or if they are all closed, the tipmost closed head of the
branch. Bookmark, tag, and branch names must not contain the ":" character.

The reserved name "tip" always identifies the most recent revision.

The reserved name "null" indicates the null revision. This is the
revision of an empty repository, and the parent of revision 0.

The reserved name "." indicates the working directory parent. If no
working directory is checked out, it is equivalent to null. If an
uncommitted merge is in progress, "." is the revision of the first
parent.