From 5b50e8bc2e426c08ce6641249581b6da6c2e5b6f Mon Sep 17 00:00:00 2001
From: Sveinung Kvilhaugsvik <sveinung84@users.sourceforge.net>
Date: Fri, 19 Feb 2021 22:09:09 +0100
Subject: [PATCH 6/6] Find missing universals in enabler requirements.

Make action_enabler_suggest_improvement() suggest removing references to
missing universals. This gives ruledit and other users of
action_enabler_suggest_improvement() access to the knowledge of missing
universals.

See osnd #41616
---
 common/actions.c      | 14 +++++++++++
 common/requirements.c | 55 +++++++++++++++++++++++++++++++++++++++++++
 common/requirements.h |  4 ++++
 3 files changed, 73 insertions(+)

diff --git a/common/actions.c b/common/actions.c
index 9ed9f6a034..944bf77f44 100644
--- a/common/actions.c
+++ b/common/actions.c
@@ -2584,6 +2584,20 @@ action_enabler_suggest_improvement(const struct action_enabler *enabler)
 
   paction = action_by_number(enabler->action);
 
+  /* Check if a universal that never will appear in the game is checked. */
+  out = req_vec_get_first_missing_univ(&enabler->actor_reqs,
+                                       action_enabler_vector_number,
+                                       enabler);
+  if (out) {
+    return out;
+  }
+  out = req_vec_get_first_missing_univ(&enabler->target_reqs,
+                                       action_enabler_vector_number,
+                                       enabler);
+  if (out) {
+    return out;
+  }
+
   /* Detect unused action enablers. */
   if (action_get_actor_kind(paction) == AAK_UNIT) {
     bool has_user = FALSE;
diff --git a/common/requirements.c b/common/requirements.c
index d7528187e3..3231a7ab9a 100644
--- a/common/requirements.c
+++ b/common/requirements.c
@@ -3747,6 +3747,61 @@ req_vec_get_first_contradiction(const struct requirement_vector *vec,
   return NULL;
 }
 
+/**********************************************************************//**
+  Returns the first universal known to always be absent in the specified
+  requirement vector with suggested solutions or NULL if no missing
+  universals were found.
+  It is the responsibility of the caller to free the suggestion when it is
+  done with it.
+  @param vec the requirement vector to look in.
+  @param get_num function that returns the requirement vector's number in
+                 the parent item.
+  @param parent_item the item that owns the vector.
+  @return the first missing universal found.
+**************************************************************************/
+struct req_vec_problem *
+req_vec_get_first_missing_univ(const struct requirement_vector *vec,
+                               requirement_vector_number get_num,
+                               const void *parent_item)
+{
+  int i;
+  req_vec_num_in_item vec_num;
+
+  if (vec == NULL || requirement_vector_size(vec) == 0) {
+    /* No vector. */
+    return NULL;
+  }
+
+  if (get_num == NULL || parent_item == NULL) {
+    vec_num = 0;
+  } else {
+    vec_num = get_num(parent_item, vec);
+  }
+
+  /* Look for contradictions */
+  for (i = 0; i < requirement_vector_size(vec); i++) {
+    struct requirement *preq = requirement_vector_get(vec, i);
+    if (universal_never_there(&preq->source)) {
+      struct req_vec_problem *problem;
+
+      problem = req_vec_problem_new(1,
+          N_("Requirement {%s} mentions %s but it will never be there."),
+          req_to_fstring(preq), universal_rule_name(&preq->source));
+
+      /* The solution is to remove the reference to the missing
+       * universal. */
+      problem->suggested_solutions[0].operation = RVCO_REMOVE;
+      problem->suggested_solutions[0].vector_number = vec_num;
+      problem->suggested_solutions[0].req = *preq;
+
+      /* Only the first missing universal is reported. */
+      return problem;
+    }
+  }
+
+  return NULL;
+}
+
 /**********************************************************************//**
   Return TRUE iff the two sources are equivalent.  Note this isn't the
   same as an == or memcmp check.
diff --git a/common/requirements.h b/common/requirements.h
index e9f5f832f6..5ffcdc3139 100644
--- a/common/requirements.h
+++ b/common/requirements.h
@@ -235,6 +235,10 @@ struct req_vec_problem *
 req_vec_get_first_contradiction(const struct requirement_vector *vec,
                                 requirement_vector_number get_num,
                                 const void *parent_item);
+struct req_vec_problem *
+req_vec_get_first_missing_univ(const struct requirement_vector *vec,
+                               requirement_vector_number get_num,
+                               const void *parent_item);
 
 
 /* General universal functions. */
-- 
2.20.1