Protect sticky module requirement whatever its load order on purge

The requirement check on purge only looked at dependent modules loaded
after the module to unload. A requirement loaded after its super-sticky
dependent, for instance reloaded after a forced unload, was purged and
left this dependent with a missing dependency, the very situation this
protection aims to avoid.

Look at dependent modules whatever their load order and drop the direct
dependent pre-check that relied on load order too. Also cover the abort
of the purge when the error raised for a retained requirement occurs
with abort_on_error configured for this sub-command.

Assisted-by: Claude:claude-fable-5-1
Signed-off-by: Xavier Delaruelle <xavier.delaruelle@cea.fr>

Author: xdelaruelle

doc/source/design/sticky-modules.rst

@@ -52,6 +52,8 @@ Specification
   and super-sticky modules
 
   - Direct and indirect requirements are preserved, even without a sticky tag
+  - Requirements are preserved whatever their load order relative to their
+    dependent, as a requirement may be loaded after its dependent
   - Only strong requirements are preserved: an alternative requirement may
     be unloaded while another loaded module still satisfies it
   - A forced ``purge`` unloads sticky modules and can unload their

tcl/modeval.tcl

@@ -961,7 +961,9 @@ proc isModuleSticky {mod} {
 
 proc getModuleStickyDependentTag {mod} {
    set sticky_tag {}
-   foreach dep_mod [getDependentLoadedModuleList [list $mod] 1 0 0 0] {
+   # look at dependents whatever their load order to also protect a
+   # requirement loaded after its sticky dependent
+   foreach dep_mod [getDependentLoadedModuleList [list $mod] 1 0 1 0] {
       if {[isModuleTagged $dep_mod super-sticky 1]} {
          set sticky_tag super-sticky
          break

testsuite/modules.50-cmds/464-sticky_purge.exp

@@ -250,6 +250,82 @@ foreach {report_mode msg reqmsg stickymsg} [list error\
 }
 
 
+# requirement loaded after its super-sticky dependent
+setenv_loaded_module [list sticky2/1.0 sticky1/1.0] [list\
+    $mp/sticky2/1.0 $mp/sticky1/1.0]
+setenv_var __MODULES_LMTAG sticky2/1.0&super-sticky
+foreach {report_mode msg reqmsg} [list error $err_superstickyunload\
+    $err_superstickyrequnload warning $warn_superstickyunload\
+    $warn_superstickyrequnload silent {} {}] {
+    setenv_var MODULES_STICKY_PURGE $report_mode
+    set ans [list]
+    if {$report_mode eq {error}} {
+        lappend ans [list ERR]
+    }
+    set tserr {}
+    if {$report_mode ne {silent}} {
+        set tserr [msg_unload sticky1/1.0 $reqmsg]\n\n[msg_unload\
+            {sticky2/1.0 <sS>} $msg]
+    }
+    testouterr_cmd sh {purge} $ans $tserr
+    testouterr_cmd sh {purge -f} $ans $tserr
+}
+
+
+# requirement loaded after its sticky dependent
+setenv_var __MODULES_LMTAG sticky2/1.0&sticky
+foreach {report_mode msg reqmsg} [list error $err_stickyunload\
+    $err_stickyrequnload warning $warn_stickyunload $warn_stickyrequnload\
+    silent {} {}] {
+    setenv_var MODULES_STICKY_PURGE $report_mode
+    set ans [list]
+    if {$report_mode eq {error}} {
+        lappend ans [list ERR]
+    }
+    set tserr {}
+    if {$report_mode ne {silent}} {
+        set tserr [msg_unload sticky1/1.0 $reqmsg]\n\n[msg_unload\
+            {sticky2/1.0 <S>} $msg]
+    }
+    testouterr_cmd sh {purge} $ans $tserr
+
+    set ans [list]
+    foreach var {__MODULES_LMPREREQ _LMFILES_ LOADEDMODULES __MODULES_LMTAG} {
+        lappend ans [list unset $var]
+    }
+    set tserr [msg_unload {sticky2/1.0 <S>} $err_stickyunloadf]
+    testouterr_cmd sh {purge -f} $ans $tserr
+}
+
+
+# skipped requirement unload aborts purge if abort_on_error is configured
+setenv_var MODULES_ABORT_ON_ERROR purge
+setenv_loaded_module [list foo/1.0 sticky2/1.0 sticky1/1.0] [list\
+    $mp/foo/1.0 $mp/sticky2/1.0 $mp/sticky1/1.0]
+setenv_var __MODULES_LMTAG sticky2/1.0&super-sticky
+
+setenv_var MODULES_STICKY_PURGE error
+set tserr [msg_unload sticky1/1.0 $err_superstickyrequnload]
+testouterr_cmd sh {purge} ERR $tserr
+# force mode disables abort behavior
+set ans [list]
+lappend ans [list set _LMFILES_ $mp/sticky2/1.0:$mp/sticky1/1.0]
+lappend ans [list set LOADEDMODULES sticky2/1.0:sticky1/1.0]
+lappend ans [list ERR]
+set tserr [msg_unload sticky1/1.0 $err_superstickyrequnload]\n\n[msg_unload\
+    {sticky2/1.0 <sS>} $err_superstickyunload]
+testouterr_cmd sh {purge -f} $ans $tserr
+
+setenv_var MODULES_STICKY_PURGE warning
+set ans [list]
+lappend ans [list set _LMFILES_ $mp/sticky2/1.0:$mp/sticky1/1.0]
+lappend ans [list set LOADEDMODULES sticky2/1.0:sticky1/1.0]
+set tserr [msg_unload sticky1/1.0 $warn_superstickyrequnload]\n\n[msg_unload\
+    {sticky2/1.0 <sS>} $warn_superstickyunload]
+testouterr_cmd sh {purge} $ans $tserr
+testouterr_cmd sh {purge -f} $ans $tserr
+
+unsetenv_var MODULES_ABORT_ON_ERROR
 unsetenv_var __MODULES_LMPREREQ
 unsetenv_var TESTSUITE_STICKY