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* lisp/emacs-lisp/package.el (package-compute-transaction): Topological sort.

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Add optional `seen' argument to detect and break infinite loops.

Fixes: debbugs:16994
This commit is contained in:
Stefan Monnier 2014-05-06 14:11:16 -04:00
parent 8e102bcc97
commit 5e87fcb1d7
2 changed files with 31 additions and 16 deletions
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28
lisp/emacs-lisp/package.el
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@ -868,7 +868,7 @@ MIN-VERSION should be a version list."
;; Also check built-in packages.
(package-built-in-p package min-version)))
(defun package-compute-transaction (packages requirements)
(defun package-compute-transaction (packages requirements &optional seen)
"Return a list of packages to be installed, including PACKAGES.
PACKAGES should be a list of `package-desc'.
@ -880,7 +880,9 @@ version of that package.
This function recursively computes the requirements of the
packages in REQUIREMENTS, and returns a list of all the packages
that must be installed. Packages that are already installed are
not included in this list."
not included in this list.
SEEN is used internally to detect infinite recursion."
;; FIXME: We really should use backtracking to explore the whole
;; search space (e.g. if foo require bar-1.3, and bar-1.4 requires toto-1.1
;; whereas bar-1.3 requires toto-1.0 and the user has put a hold on toto-1.0:
@ -893,15 +895,22 @@ not included in this list."
(dolist (pkg packages)
(if (eq next-pkg (package-desc-name pkg))
(setq already pkg)))
(cond
(already
(when already
(if (version-list-<= next-version (package-desc-version already))
;; Move to front, so it gets installed early enough (bug#14082).
(setq packages (cons already (delq already packages)))
;; `next-pkg' is already in `packages', but its position there
;; means it might be installed too late: remove it from there, so
;; we re-add it (along with its dependencies) at an earlier place
;; below (bug#16994).
(if (memq already seen) ;Avoid inf-loop on dependency cycles.
(message "Dependency cycle going through %S"
(package-desc-full-name already))
(setq packages (delq already packages))
(setq already nil))
(error "Need package `%s-%s', but only %s is being installed"
next-pkg (package-version-join next-version)
(package-version-join (package-desc-version already)))))
(cond
(already nil)
((package-installed-p next-pkg next-version) nil)
(t
@ -933,12 +942,13 @@ but version %s required"
(t (setq found pkg-desc)))))
(unless found
(if problem
(error problem)
(error "%s" problem)
(error "Package `%s-%s' is unavailable"
next-pkg (package-version-join next-version))))
(setq packages
(package-compute-transaction (cons found packages)
(package-desc-reqs found))))))))
(package-desc-reqs found)
(cons found seen))))))))
packages)
(defun package-read-from-string (str)