Merge pull request #1814 from michaellilltokiwa/issue/169

improve backward type propagation for arrays

src/dev/flang/ast/InlineArray.java

@@ -119,7 +119,7 @@ AbstractType typeIfKnown()
                                               _elements.iterator());
             _type = Types.t_ERROR;
           }
-        if (_type == null)
+        else
           {
             _type =
               t == null ? null :
@@ -162,7 +162,7 @@ public Expr propagateExpectedType(Resolution res, AbstractFeature outer, Abstrac
               {
                 e.propagateExpectedType(res, outer, elementType);
               }
-            _type = t;
+            _type = Types.resolved.f_array.resultTypeIfPresent(res, new List<>(elementType));
           }
       }
     return this;
@@ -181,7 +181,8 @@ private AbstractType elementType(AbstractType t)
     if (PRECONDITIONS) require
       (t != null);
 
-    if (t.featureOfType() == Types.resolved.f_array &&
+    // NYI see issue: #1817
+    if (Types.resolved.f_array.inheritsFrom(t.featureOfType()) &&
         t.generics().size() == 1)
       {
         return t.generics().get(0);

tests/reg_issue169_backward_type_propagation_array/Makefile

@@ -0,0 +1,27 @@
+# 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
+#
+#  Author: Fridtjof Siebert ([email protected])
+#
+# -----------------------------------------------------------------------
+
+override NAME = issue169
+include ../positive.mk

tests/reg_issue169_backward_type_propagation_array/issue169.fz

@@ -0,0 +1,16 @@
+issue169 =>
+
+  a array i32 := []
+  b Sequence i32 := []
+  c Sequence u8 := []
+  d Sequence f32 := [0,1,2]
+  e Sequence (Sequence i16) := [[0,1],[2]]
+  # NYI does not work yet
+  # f := [u8 4, 3, 3]
+
+  say (type_of a)
+  say (type_of b)
+  say (type_of c)
+  say (type_of d)
+  say (type_of e)
+  # say (type_of f)