Merge pull request #3386 from tokiwa-software/fix_3362

ast: When checking actual type par against constraints, do not walk through inh chain of choice Fix #3362

src/dev/flang/ast/AbstractType.java

@@ -469,6 +469,7 @@ public boolean constraintAssignableFrom(AbstractType actual)
     var result = containsError()                   ||
       actual.containsError()                       ||
       this  .compareTo(actual               ) == 0 ||
+      this  .compareTo(Types.resolved.t_Any ) == 0 ||
       actual.isVoid();
     if (!result && !isGenericArgument())
       {
@@ -482,23 +483,12 @@ public boolean constraintAssignableFrom(AbstractType actual)
               (actual.feature() != null || Errors.any());
             if (actual.feature() != null)
               {
-                if (actual.feature() == feature())
+                result = actual.feature() == feature() &&
+                         genericsAssignable(actual); // NYI: Check: What about open generics?
+                for (var p: actual.feature().inherits())
                   {
-                    if (genericsAssignable(actual)) // NYI: Check: What about open generics?
-                      {
-                        result = true;
-                      }
-                  }
-                if (!result)
-                  {
-                    for (var p: actual.feature().inherits())
-                      {
-                        var pt = p.type().applyTypePars(actual);
-                        if (constraintAssignableFrom(pt))
-                          {
-                            result = true;
-                          }
-                      }
+                    result |= !p.calledFeature().isChoice() &&
+                      constraintAssignableFrom(p.type().applyTypePars(actual));
                   }
               }
           }

tests/reg_issue3362/Makefile

@@ -0,0 +1,25 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test Makefile
+#
+# -----------------------------------------------------------------------
+
+override NAME = reg_issue3362
+include ../simple_and_negative.mk

tests/reg_issue3362/reg_issue3362.fz

@@ -0,0 +1,65 @@
+# This file is part of the Fuzion language implementation.
+#
+# The Fuzion language implementation is free software: you can redistribute it
+# and/or modify it under the terms of the GNU General Public License as published
+# by the Free Software Foundation, version 3 of the License.
+#
+# The Fuzion language implementation is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+# License for more details.
+#
+# You should have received a copy of the GNU General Public License along with The
+# Fuzion language implementation.  If not, see <https://www.gnu.org/licenses/>.
+
+
+# -----------------------------------------------------------------------
+#
+#  Tokiwa Software GmbH, Germany
+#
+#  Source code of Fuzion test
+#
+# -----------------------------------------------------------------------
+
+# Test choice type used as actual type parameter without matching the contstraint
+#
+reg_issue3362 is
+
+
+  # original example from issue #3362
+  #
+  base32_test is
+  my_c : choice String (array u8) is
+  mk_choice(x my_c) => x
+
+  # RFC 4618 test vectors
+  base32_test_vectors array (tuple my_c String) :=
+    [(mk_choice "fo", "MZXQ===="),
+     (mk_choice "foo", "MZXW6===")]
+
+  dummy_decode(arr array u8) outcome (array u8) => [0,0,0]
+
+  dec_test =>
+    for tup in base32_test_vectors do
+      (plain_expected, code) := tup
+      out :=
+        match dummy_decode code.utf8.as_array
+          arr array u8 =>
+            plain_actual := String.type.from_bytes arr
+            if plain_actual != plain_expected     # 1. should flag an error: `choice String (array u8)` is not assignable to `property.equatable`
+              error "decoding $code produced '$plain_actual' but should have been '$plain_expected'"
+            else
+              outcome "ok"
+          e error => error "error in test data"
+    until !out.ok
+      out.err.as_string
+    else
+      "RFC 4648 test vectors are decoded correctly"
+  say dec_test
+
+
+  # minimalistic-example
+  #
+  c : choice i32 unit is
+  a c := 0
+  _ := 0 = a   # 2. should flag an error: `choice i32 unit` is not assignable to `property.equatable`

tests/reg_issue3362/reg_issue3362.fz.expected_err

@@ -0,0 +1,15 @@
+
+--CURDIR--/reg_issue3362.fz:65:10: error 1: Incompatible type parameter
+  _ := 0 = a   # 2. should flag an error: `choice i32 unit` is not assignable to `property.equatable`
+---------^
+formal type parameter 'T' with constraint 'property.equatable'
+actual type parameter 'reg_issue3362.this.c'
+
+
+--CURDIR--/reg_issue3362.fz:49:29: error 2: Incompatible type parameter
+            if plain_actual != plain_expected     # 1. should flag an error: `choice String (array u8)` is not assignable to `property.equatable`
+----------------------------^^
+formal type parameter 'T' with constraint 'property.equatable'
+actual type parameter 'reg_issue3362.this.my_c'
+
+2 errors.