Merge branch '6.4' into 7.0

* 6.4:
  Added description to improved bin/console debug:container --env-vars …

Author: javiereguiluz

configuration.rst

@@ -977,19 +977,21 @@ Use the ``debug:dotenv`` command to understand how Symfony parses the different
     $ php bin/console debug:dotenv foo
 
 Additionally, and regardless of how you set environment variables, you can see all
-environment variables, with their values, referenced in Symfony's container configuration:
+environment variables, with their values, referenced in Symfony's container configuration,
+you can also see the number of occurrences of each environment variable in the container:
 
 .. code-block:: terminal
 
     $ php bin/console debug:container --env-vars
 
-    ---------------- ----------------- ---------------------------------------------
-     Name             Default value     Real value
-    ---------------- ----------------- ---------------------------------------------
-     APP_SECRET       n/a               "471a62e2d601a8952deb186e44186cb3"
-     FOO              "[1, "2.5", 3]"   n/a
-     BAR              null              n/a
-    ---------------- ----------------- ---------------------------------------------
+    ------------ ----------------- ------------------------------------ -------------
+     Name         Default value     Real value                           Usage count
+    ------------ ----------------- ------------------------------------ -------------
+     APP_SECRET   n/a               "471a62e2d601a8952deb186e44186cb3"   2
+     BAR          n/a               n/a                                  1
+     BAZ          n/a               "value"                              0
+     FOO          "[1, "2.5", 3]"   n/a                                  1
+    ------------ ----------------- ------------------------------------ -------------
 
     # you can also filter the list of env vars by name:
     $ php bin/console debug:container --env-vars foo