From c6fc5d774cf5f7dd4f01d010d38d91ae18fad816 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Fri, 11 Nov 2022 22:13:04 +0000
Subject: [PATCH] Fix wrong overload selection with condition conversion. Issue
 #570

---
 src/names.c               | 30 ++++++++++++++++++++++++++++++
 test/regress/issue570.vhd | 36 ++++++++++++++++++++++++++++++++++++
 test/regress/testlist.txt |  1 +
 3 files changed, 67 insertions(+)
 create mode 100644 test/regress/issue570.vhd

diff --git a/src/names.c b/src/names.c
index c593eab6..5c405c00 100644
--- a/src/names.c
+++ b/src/names.c
@@ -151,6 +151,7 @@ typedef A(tracked_type_t) tracked_type_list_t;
 struct type_set {
    tracked_type_list_t  members;
    type_set_t          *down;
+   bool                 cconv;
 };
 
 static type_t _solve_types(nametab_t *tab, tree_t expr);
@@ -2218,6 +2219,33 @@ static tree_t finish_overload_resolution(overload_t *o)
 
    overload_trace_candidates(o, "before final pruning");
 
+   // If this call appears in a context that allows condition
+   // conversion, and there are multiple candidates at least one of
+   // which returns BOOLEAN, then prune the others that were only
+   // considered due to condition conversion.
+   if (o->candidates.count > 1 && o->nametab->top_type_set->cconv) {
+      type_t boolean = std_type(NULL, STD_BOOLEAN);
+
+      int nboolean = 0;
+      for (unsigned i = 0; i < o->candidates.count; i++) {
+         type_t rtype = type_result(tree_type(o->candidates.items[i]));
+         if (type_eq(rtype, boolean))
+            nboolean++;
+      }
+
+      if (nboolean > 0) {
+         unsigned wptr = 0;
+         for (unsigned i = 0; i < o->candidates.count; i++) {
+            type_t rtype = type_result(tree_type(o->candidates.items[i]));
+            if (!type_eq(rtype, boolean))
+               overload_prune_candidate(o, i);
+            else
+               o->candidates.items[wptr++] = o->candidates.items[i];
+         }
+         ATRIM(o->candidates, wptr);
+      }
+   }
+
    // Allow explicitly defined operators to hide implicitly defined ones
    // in different scopes. This is required behaviour in VHDL-2008 (see
    // section 12.4) and an optional rule relaxation in earlier revisions.
@@ -3901,6 +3929,8 @@ type_t solve_condition(nametab_t *tab, tree_t *expr, type_t constraint)
                type_set_add(tab, p0_type, dd->tree);
             }
          }
+
+         tab->top_type_set->cconv = true;
       }
    }
 
diff --git a/test/regress/issue570.vhd b/test/regress/issue570.vhd
new file mode 100644
index 00000000..143af6e0
--- /dev/null
+++ b/test/regress/issue570.vhd
@@ -0,0 +1,36 @@
+package pack is
+    function "=" (L: bit; R: bit) return bit;
+end package;
+
+package body pack is
+    function "=" (L: bit; R: bit) return bit is
+    begin
+        if L = R then
+            return '1';
+        else
+            return '0';
+        end if;
+    end function;
+end package body;
+
+-------------------------------------------------------------------------------
+
+use work.pack.all;
+
+entity issue570 is
+end entity;
+
+architecture test of issue570 is
+    signal x : bit := '1';
+begin
+
+    p1: process is
+    begin
+        assert (bit'( '1' ) = bit'( '1' )) = '1';
+        if x = '0' then
+            assert false;
+        end if;
+        wait;
+    end process;
+
+end architecture;
diff --git a/test/regress/testlist.txt b/test/regress/testlist.txt
index c4f961af..a4565814 100644
--- a/test/regress/testlist.txt
+++ b/test/regress/testlist.txt
@@ -688,3 +688,4 @@ case14          normal,2008
 cmdline4        shell
 record38        fail,gold,2008
 issue560        normal,2008
+issue570        normal,2008
-- 
2.39.2