Don't allow release versions that depend upon snapshots.

TUTORIAL.md

@@ -118,12 +118,14 @@ This becomes:
 Sometimes versions will end in "-SNAPSHOT". This means that it is not
 an official release but a development build. Relying on snapshot
 dependencies is discouraged but is sometimes necessary if you need bug
-fixes, etc. that have not made their way into a release yet. Adding a
-snapshot dependency to your project will cause Leiningen to actively
-go seek out the latest version of the dependency once a day when you
-run <tt>lein deps</tt>, (whereas normal release versions are cached in
-the local repository) so if you have a lot of snapshots it will slow
-things down.
+fixes, etc. that have not made their way into a release yet. However,
+snapshot versions are not guaranteed to stick around, so it's
+important that released code never depends upon snapshot versions that
+you don't control. Adding a snapshot dependency to your project will
+cause Leiningen to actively go seek out the latest version of the
+dependency once a day when you run <tt>lein deps</tt>, (whereas normal
+release versions are cached in the local repository) so if you have a
+lot of snapshots it will slow things down.
 
 Speaking of the local repository, all the dependencies you pull in
 using Leiningen or Maven get cached in $HOME/.m2/repository since
@@ -158,7 +160,10 @@ instead of a single version:
 
 See [Maven's version range
 specification](http://maven.apache.org/plugins/maven-enforcer-plugin/rules/versionRanges.html)
-for details.
+for details. Don't do this unless you have manually confirming that it
+works with each of those versions though. You can't assume that your
+dependencies will use semantic versions; some projects even introduce
+backwards-incompatible changes in bugfix point releases.
 
 ## Dev Dependencies
 

src/leiningen/pom.clj

@@ -13,9 +13,18 @@
   It should not be considered canonical data. For more information see
   https://github.com/technomancy/leiningen -->\n")
 
+(defn check-for-snapshot-deps [project]
+  (when (and (not (re-find #"SNAPSHOT" (:version project)))
+             (not (System/getenv "LEIN_SNAPSHOTS_IN_RELEASE"))
+             (some #(re-find #"SNAPSHOT" (second %)) (:dependencies project)))
+    (throw (Exception. (str "Release versions may not depend upon snapshots."
+                            "\nSet the LEIN_SNAPSHOTS_IN_RELEASE environment"
+                            " variable to override this.")))))
+
 (defn make-pom
   ([project] (make-pom project false))
   ([project disclaimer?]
+     (check-for-snapshot-deps project)
      (with-open [w (StringWriter.)]
        (.writeModel (MavenProject. (make-model project)) w)
        (when disclaimer?

test/test_pom.clj

@@ -17,3 +17,8 @@
   (let [model (make-model test-project)]
     (is (= "src" (-> model .getBuild .getSourceDirectory)))
     (is (= "test" (-> model .getBuild .getTestSourceDirectory)))))
+
+(deftest test-snapshot-checking
+  (is (thrown? Exception (pom (assoc test-project
+                                :version "1.0"
+                                :dependencies [['clojure "1.0.0-SNAPSHOT"]])))))

test_projects/sample/project.clj

@@ -3,7 +3,7 @@
 ;; just want a basic project to work from, generate a new one with
 ;; "lein new".
 
-(def clj-version "1.1.0-master-SNAPSHOT")
+(def clj-version "1.1.0")
 
 (defproject nomnomnom "0.5.0-SNAPSHOT"
   :description "A test project"