Revert "Enable HOMEBREW_AUTOREMOVE by autoremove_default"

`autoremove` is destructive, and it can be difficult for users to
recover from it occuring when they weren't expecting it.

Fixes #17363
Fixes Homebrew/discussions#5395

This reverts commit 3d11416.
This reverts commit efb14a0.

Library/Homebrew/cleanup.rb

@@ -287,11 +287,7 @@ def clean!(quiet: false, periodic: false)
           cleanup_formula(formula, quiet:, ds_store: false, cache_db: false)
         end
 
-        if ENV["HOMEBREW_AUTOREMOVE"].present?
-          opoo "HOMEBREW_AUTOREMOVE is now a no-op as it is the default behaviour. " \
-               "Set HOMEBREW_NO_AUTOREMOVE=1 to disable it."
-        end
-        Cleanup.autoremove(dry_run: dry_run?) unless Homebrew::EnvConfig.no_autoremove?
+        Cleanup.autoremove(dry_run: dry_run?) if Homebrew::EnvConfig.autoremove?
 
         cleanup_cache
         cleanup_empty_api_source_directories

Library/Homebrew/cmd/uninstall.rb

@@ -77,11 +77,7 @@ def run
           )
         end
 
-        if ENV["HOMEBREW_AUTOREMOVE"].present?
-          opoo "HOMEBREW_AUTOREMOVE is now a no-op as it is the default behaviour. " \
-               "Set HOMEBREW_NO_AUTOREMOVE=1 to disable it."
-        end
-        Cleanup.autoremove unless Homebrew::EnvConfig.no_autoremove?
+        Cleanup.autoremove if Homebrew::EnvConfig.autoremove?
       end
     end
   end

Library/Homebrew/env_config.rb

@@ -46,7 +46,11 @@ module EnvConfig
         description: "If `HOMEBREW_ARTIFACT_DOMAIN` and `HOMEBREW_ARTIFACT_DOMAIN_NO_FALLBACK` are both set, " \
                      "if the request to `HOMEBREW_ARTIFACT_DOMAIN` fails then it Homebrew will error rather than " \
                      "trying any other/default URLs.",
-        boolean:     true,
+      },
+      HOMEBREW_AUTOREMOVE:                       {
+        description: "If set, calls to `brew cleanup` and `brew uninstall` will automatically " \
+                     "remove unused formula dependents and if `HOMEBREW_NO_INSTALL_CLEANUP` is not set, " \
+                     "`brew cleanup` will start running `brew autoremove` periodically.",
       },
       HOMEBREW_AUTO_UPDATE_SECS:                 {
         description:  "Run `brew update` once every `HOMEBREW_AUTO_UPDATE_SECS` seconds before some commands, " \
@@ -306,11 +310,6 @@ module EnvConfig
                      "For more information, see: <https://docs.brew.sh/Analytics>",
         boolean:     true,
       },
-      HOMEBREW_NO_AUTOREMOVE:                    {
-        description: "If set, calls to `brew cleanup` and `brew uninstall` will not automatically " \
-                     "remove unused formula dependents.",
-        boolean:     true,
-      },
       HOMEBREW_NO_AUTO_UPDATE:                   {
         description: "If set, do not automatically update before running some commands, e.g. " \
                      "`brew install`, `brew upgrade` and `brew tap`. Preferably, " \

docs/Manpage.md

@@ -3519,6 +3519,12 @@ command execution e.g. `$(cat file)`.
   both set, if the request to `HOMEBREW_ARTIFACT_DOMAIN` fails then it Homebrew
   will error rather than trying any other/default URLs.
 
+`HOMEBREW_AUTOREMOVE`
+
+: If set, calls to `brew cleanup` and `brew uninstall` will automatically remove
+  unused formula dependents and if `HOMEBREW_NO_INSTALL_CLEANUP` is not set,
+  `brew cleanup` will start running `brew autoremove` periodically.
+
 `HOMEBREW_AUTO_UPDATE_SECS`
 
 : Run `brew update` once every `HOMEBREW_AUTO_UPDATE_SECS` seconds before some
@@ -3837,11 +3843,6 @@ command execution e.g. `$(cat file)`.
 : If set, do not send analytics. Google Analytics were destroyed. For more
   information, see: <https://docs.brew.sh/Analytics>
 
-`HOMEBREW_NO_AUTOREMOVE`
-
-: If set, calls to `brew cleanup` and `brew uninstall` will not automatically
-  remove unused formula dependents.
-
 `HOMEBREW_NO_AUTO_UPDATE`
 
 : If set, do not automatically update before running some commands, e.g. `brew

manpages/brew.1

@@ -2250,6 +2250,9 @@ Prefix all download URLs, including those for bottles, with this value\. For exa
 \fBHOMEBREW_ARTIFACT_DOMAIN_NO_FALLBACK\fP
 If \fBHOMEBREW_ARTIFACT_DOMAIN\fP and \fBHOMEBREW_ARTIFACT_DOMAIN_NO_FALLBACK\fP are both set, if the request to \fBHOMEBREW_ARTIFACT_DOMAIN\fP fails then it Homebrew will error rather than trying any other/default URLs\.
 .TP
+\fBHOMEBREW_AUTOREMOVE\fP
+If set, calls to \fBbrew cleanup\fP and \fBbrew uninstall\fP will automatically remove unused formula dependents and if \fBHOMEBREW_NO_INSTALL_CLEANUP\fP is not set, \fBbrew cleanup\fP will start running \fBbrew autoremove\fP periodically\.
+.TP
 \fBHOMEBREW_AUTO_UPDATE_SECS\fP
 Run \fBbrew update\fP once every \fBHOMEBREW_AUTO_UPDATE_SECS\fP seconds before some commands, e\.g\. \fBbrew install\fP, \fBbrew upgrade\fP and \fBbrew tap\fP\&\. Alternatively, disable auto\-update entirely with \fBHOMEBREW_NO_AUTO_UPDATE\fP\&\.
 .RS
@@ -2509,9 +2512,6 @@ If set, do not send analytics\. Google Analytics were destroyed\. For more infor
 .UR https://docs\.brew\.sh/Analytics
 .UE
 .TP
-\fBHOMEBREW_NO_AUTOREMOVE\fP
-If set, calls to \fBbrew cleanup\fP and \fBbrew uninstall\fP will not automatically remove unused formula dependents\.
-.TP
 \fBHOMEBREW_NO_AUTO_UPDATE\fP
 If set, do not automatically update before running some commands, e\.g\. \fBbrew install\fP, \fBbrew upgrade\fP and \fBbrew tap\fP\&\. Preferably, run this less often by setting \fBHOMEBREW_AUTO_UPDATE_SECS\fP to a value higher than the default\. Note that setting this and e\.g\. tapping new taps may result in a broken configuration\. Please ensure you always run \fBbrew update\fP before reporting any issues\.
 .TP