Issue 3913 - Emit better diagnostics for invalid enum member lookups

src/mtype.c

@@ -7261,7 +7261,22 @@ Expression *TypeEnum::dotExp(Scope *sc, Expression *e, Identifier *ident, int fl
         {
             return getProperty(e->loc, ident, flag);
         }
-        return sym->getMemtype(Loc())->dotExp(sc, e, ident, flag);
+
+        if (flag == 0)
+            flag = 1;  // silence lookup errors for memtype
+
+        Expression *res = sym->getMemtype(Loc())->dotExp(sc, e, ident, flag);
+        if (!res)
+        {
+            Dsymbol *s = sym->search_correct(ident);
+            if (s)
+                e->error("no property '%s' for type '%s'. Did you mean '%s.%s' ?", ident->toChars(), toChars(), toChars(), s->toChars());
+            else
+                e->error("no property '%s' for type '%s'", ident->toChars(), toChars());
+
+            return new ErrorExp();
+        }
+        return res;
     }
     EnumMember *m = s->isEnumMember();
     return m->getVarExp(e->loc, sc);

test/fail_compilation/diag3913.d

@@ -0,0 +1,15 @@
+/*
+TEST_OUTPUT:
+---
+fail_compilation/diag3913.d(13): Error: no property 'foobardoo' for type 'Foo'
+fail_compilation/diag3913.d(14): Error: no property 'secon' for type 'Foo'. Did you mean 'Foo.second' ?
+---
+*/
+
+module diag3913;
+void main()
+{
+    enum Foo { first, second }
+    auto a = Foo.foobardoo;
+    auto b = Foo.secon;
+}