Fix Issue 23172 - [REG2.100] Wrong cast inserted for ternary operator and non-int enums

Author: BorisCarvajal

src/dmd/dcast.d

@@ -1107,9 +1107,14 @@ MATCH implicitConvTo(Expression e, Type t)
 
     MATCH visitCond(CondExp e)
     {
-        auto result = visit(e);
-        if (result != MATCH.nomatch)
-            return result;
+        e.econd = e.econd.optimize(WANTvalue);
+        const opt = e.econd.toBool();
+        if (opt.isPresent())
+        {
+            auto result = visit(e);
+            if (result != MATCH.nomatch)
+                return result;
+        }
 
         MATCH m1 = e.e1.implicitConvTo(t);
         MATCH m2 = e.e2.implicitConvTo(t);

test/compilable/test23172.d

@@ -0,0 +1,33 @@
+// https://issues.dlang.org/show_bug.cgi?id=23172
+
+enum E : ubyte { // `ubyte` is needed to trigger the bug
+    A,
+    B,
+}
+
+struct S {
+    E e;
+}
+
+void compiles(bool b, S s) {
+    E e = b ? E.A : s.e;
+}
+
+void errors(bool b, const ref S s) {
+    E e = b ? E.A : s.e;
+}
+
+// from https://issues.dlang.org/show_bug.cgi?id=23188
+
+enum Status : byte
+{
+    A, B, C
+}
+
+Status foo()
+{
+    Status t = Status.A;
+    const Status s = t;
+
+    return (s == Status.A) ? Status.B : s;  // <-- here
+}