Add support for semantic version numbers in installer

First pass review. Not yet tested, not checked for missing fallback scenarios due to the extra version level.

1. +++ b/core/includes/install.core.inc
   @@ -1338,38 +1332,38 @@ function install_get_localization_release($version = \Drupal::VERSION) {
   +      // Dev release: the previous point release (e.g., 8.2.0-dev falls back to
   +      // 8.1.0) or any unstable release (e.g., 8.0.0-dev falls back to 8.0.0-rc1,
   +      // 8.0.0-beta1 or 8.0.0-alpha12)
          case 'dev':
   

   Comment line > 80 chars and not ending with a period.

[edit: rephrased]

2. +++ b/core/includes/install.core.inc
   @@ -1378,28 +1372,40 @@ function install_get_localization_release($version = \Drupal::VERSION) {
   -      'core' => $core . '.x',
   +      'core' => $core . '.' . $info['minor']. '.x',
          'version' => $alternative,
   

   "core" format does not have a minor. Unchanged at 8.x, etc.

3. +++ b/core/includes/install.core.inc
   @@ -1378,28 +1372,40 @@ function install_get_localization_release($version = \Drupal::VERSION) {
   +  // All releases may fall back to the previous major release (e.g., 8.1 falls
   +  // back to 7.0, 8.x-dev falls back to 7.0). This will probably only be used
   +  // for early dev releases or languages with an inactive translation team.
   +  if ($info['major'] == 8) {
   

   "8.1" should be "8.1.1". "8.x-dev" should be "8.0.x-dev".

   Add note that this should be revisited in the 9.0.x branch to fall back to 8.0.0.

4. +++ b/core/includes/install.core.inc
   @@ -1378,28 +1372,40 @@ function install_get_localization_release($version = \Drupal::VERSION) {
   +      'core' => $prev_major . '0.x',
   

   See above.

I'm tested and reviewed the last patch, the fix worked for me, the code seems to be ok.
(My patch only fixes some minor coding style issues, so I put this RTBC.)

This should have automated tests (or update existing ones).

• Updated the test cases.
• Added new test cases for the point releases.
• Fixed the logic based on the test changes.

2) Don't understand why the changes in core/modules/migrate_drupal/src/Tests/d6/MigrateAggregatorFeedTest.php and core/modules/migrate_drupal/src/Tests/d6/MigrateAggregatorItemTest.php are included in the patch.

Sorry for that, wrong diff.

Now I'm updated it, included your last changes (from #12), and also changed some comments. The failing test is also fixed.
Interdiff form #10.

1) Not in position to say if the change in core/modules/locale/src/Tests/LocaleUpdateInterfaceTest.php is correct.

They should be correct.
The only question is that we really need fallback for point versions (8.5.4 -> 8.5.3), or it should be enough to fallback to the .0 version (8.5.4 -> 8.5.0)? (Because it's not likely to every point version will have a translation, and even it have after install it can be updated to the freshest easily.)
If we don't need it the code and the test also should be changed.

+++ b/core/includes/install.core.inc
@@ -1308,90 +1307,103 @@ function install_check_localization_server($uri) {
+  // wasn't introduse before "alpha13". However, we have already gotten to

+++ b/core/includes/install.core.inc
@@ -1308,90 +1307,103 @@ function install_check_localization_server($uri) {
+    // Below we assume that for all dev, alpha, beta or rc releases
+    // the patch level is 0. Modify code below and include $info['patch']
+    // if the assumption is wrong.

+++ b/core/includes/install.core.inc
@@ -1308,90 +1307,103 @@ function install_check_localization_server($uri) {
+      // Dev release: The previous point release (e.g., 8.2.0-dev falls back

+++ b/core/includes/install.core.inc
@@ -1308,90 +1307,103 @@ function install_check_localization_server($uri) {
+      // Dev release: The previous point release (e.g., 8.2.0-dev falls back
+      // to 8.1.0) or any unstable release (e.g., 8.0.0-dev falls back to
+      // 8.0.0-rc1, 8.0.0-beta1 or 8.0.0-alpha1).
       case 'dev':
         if ($info['minor'] >= 1) {
-          $alternatives[] = $info['major'] . '.' . ($info['minor'] - 1);
+          $alternatives[] = $info['major'] . '.' . ($info['minor'] - 1) . '.0';
         }
         else {

Asking people to redownload the translation immediately after installing isn't user friendly.

There is always room for improvement. I suggest to create a follow-up for this.

My only question is: Isn't there rc/beta/alpha releases for 8.x.0 when X > 0?

I have no information that we will. We can fix it when it comes up, also in a separate issue.

Removing test tags as we have now both manual and automated test coverage.

I have small digression into issue priority. I've bumped it up, because I think this is a really major bug. Right now, installator takes really old .po file, with really outdated strings, related to many other, already fixed issues (like #1317884: Remove all instances of <none>, <Hidden> and <br/> from translatable strings because they lead to import errors). I was so confused about it so I started digging into installator and found the reason - missing support for semantic versioning.
Conclusion:
This issue should be fixed and committed asap.

Just talked to Alex Pott on future version numbers. We should anticipate on versions like "8.1.0-rc1"

• Fixed everything from #20.
• Changed behavior for rc point releases (#23)
• The fallback chain for 8.2.0-rc2 is '8.2.0-rc2', '8.2.0-rc1', '8.1.0', '8.0.0', '7.0'. Discussed it with @Sutharsan, '8.1.0' is better there, but not necessary, but the code is also less complicated this way.

(I don't know how important or how frequently is this code changing, but it's very ugly and hard to work on it, probably it should be completely refactored in an other issue.)

Further discussed future release versions with Alex Pott in IRC:
alexpott: You confirmed that we may expect 8.1.0-rc* releases. What about beta/alpha for 8.1.0 and onwards? e.g. 8.1.0-beta1 (c.c. DesireJM)
Sutharsan: we'll talk about this in between the committers

Lets see if we can keep this option open in the code, so we do not need to change it again when is gets decided.

I'm added the fallback for 8.x.0-rc -> 8.x.0-beta1.

There are also some other inconsistent fallback chains, like:

• '8.0.0-beta2', '8.0.0-beta1', '7.0' should include an alpha fallback
• 8.9.0-dev falls back to '8.8.0', '7.0', while at least 8.0.0 should be included there

But the current code is really hard to change, and any new rule could overcomplicate it. So at this point I suggest to commit this when it's possible since the original bug is fixed, and submit a followup issue for make more consistent fallback chains and a refactor for the logic.

+++ b/core/includes/install.core.inc
@@ -1396,6 +1396,7 @@ function install_get_localization_release($version = \Drupal::VERSION) {
         // Minor releases can have rc releases, but not beta or alpha.
         if ($info['minor'] > 0) {
+          $alternatives[] = $info['major'] . '.' . ($info['minor']) . '.0-beta1';
           $alternatives[] = $info['major'] . '.' . ($info['minor'] - 1) . '.0';
           $alternatives[] = $info['major'] . '.0.0';

Comment needs to be updated

+++ b/core/modules/system/src/Tests/Installer/InstallerTranslationVersionUnitTest.php
@@ -62,56 +62,83 @@ protected function assertVersionFallback($version, $fallback, $message = '', $gr
-    $version = '8.0-beta1';
-    $fallback = array('8.0-beta1', '8.0-alpha2', '7.0');
+    $version = '8.0.0-beta1';
+    $fallback = array('8.0.0-beta1', '8.0.0-alpha1', '7.0');

Add test cases for 8.1.0-beta1 and -beta*

Discussed with Désiré to finalise this issue to handle semantic 8.x.0-dev/beta/alpha releases too. Désiré has ideas for refactoring the code, but we will do that in a separate issue.

Queued for automated testing.

@hansfn - I really like your work! Thanks!
Anyway, I've added a few changes to cover more cases, removed trailing whitespace in tests file, added a sentence to explain that duplicated alternatives will be removed at the end of process.
New case covered:

• added rc1 as a fallback to current minor version with patch == 0 (although I'm pretty sure that rc3 and rc2 are even more important and should be taken before rc1)

I've forgotten about tests

added rc1 as a fallback to current minor version with patch == 0 (although I'm pretty sure that rc3 and rc2 are even more important and should be taken before rc1)

It was never the intention of this hardcoded version fallback to be complete. It is easy to fall back to the first (rc1, beta1), only with an up to date list of releases (like Update module uses) is needed to get the most recent release. The latter is way out of scope of this issue.

I'm like #34, it simplifies the logic, and introducing reasonable fallback chains, it also introduce the suggested change from #29. So I'm suggesting RTBC here.

In this patch I'm just changing some coding standard problems (long arrays are in one line again just to match the style in the same file), and adding only one logic change: 8.1.0-foo1 will now fallback to 8.1.0 before 7.0 because it's not to hard to do, while in the translation versions will be huge differences.

8.1.0-foo1 will now fallback to 8.1.0 before 7.0

I'm not sure if this fallback is necessary because every 8.x.0-foo1 should be released before 8.x.0.

I'm not sure if this fallback is necessary because every 8.x.0-foo1 should be released before 8.x.0.

No, it's an other case: valid extra names (dev, alpha, beta, rc) should be released before the final version release, and all these cases are handled. But 'foo1' here is an example for an invalid extra name, which should not exists. So if something like this happens we should do something, and I think it's better to fallback some fresher version than only to 7.0.

You are absolutely right that we should do something, so...

+++ b/core/modules/system/src/Tests/Installer/InstallerTranslationVersionUnitTest.php
@@ -62,56 +62,84 @@ protected function assertVersionFallback($version, $fallback, $message = '', $gr
+    $version = '8.0.0-foo2';
+    $fallback = array('8.0.0', '7.0');
+    $this->assertVersionFallback($version, $fallback);

...so probably we should extend Test above, by adding another one for version 8.3.0-foo2, with fallback path: 8.3.0, 8.2.0, 8.0.0, 7.0 what is covered by your last patch, or extend fallbacks list of fake version with three steps more: 8.3.0, 8.3.0-rc1, 8.3.0-beta1, 8.3.0-alpha1, 8.2.0, 8.0.0, 7.0.
Fallbacks 8.2.0 and 8.0.0 was already covered by #30:

+++ b/core/includes/install.core.inc
@@ -1308,90 +1307,87 @@ function install_check_localization_server($uri) {
+    // All unstable releases except the zero release: The previous minor release
+    // and the zero release. Duplicates will be removed later.
+    if ($info['minor'] > 0) {
+      $alternatives[] = $info['major'] . '.' . ($info['minor'] - 1) . '.0';
+      $alternatives[] = $info['major'] . '.0.0';
     }

What do you think?

Later today I'll remove "Duplicates will be removed later" from comments (somehow I've missed "The fallback detection is relaxed..." string), than patch will be ready to commit.

Ok, here's patch and interdiff

Here is interdiff with right, .txt extension.

Committed 9deda26 and pushed to 8.0.x. Thanks!