Compiler: fix bug in type filtering regarding not (!). Fixes #4243

crystal-lang · Apr 10, 2017 · 9713e42 · 9713e42
1 parent 3eef15a
commit 9713e42
Showing 2 changed files with 34 additions and 3 deletions.
diff --git a/spec/compiler/semantic/not_spec.cr b/spec/compiler/semantic/not_spec.cr
@@ -50,4 +50,30 @@ describe "Semantic: not" do
       z
       )) { int32 }
   end
+
+  it "doesn't restrict and" do
+    assert_type(%(
+      a = 1 || nil
+      z = nil
+      if !(a && (1 == 2))
+        z = a
+      end
+      z
+      )) { nilable int32 }
+  end
+
+  it "doesn't restrict and in while (#4243)" do
+    assert_type(%(
+      x = nil
+      y = nil
+      z = nil
+
+      while !(x && y)
+        z = x
+        x = 1
+      end
+
+      z
+      )) { nilable int32 }
+  end
 end
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
@@ -2850,11 +2850,16 @@ module Crystal
       node.update
 
       if needs_type_filters? && (type_filters = @type_filters)
-        @type_filters = type_filters.not
-      else
-        @type_filters = nil
+        # `Not` can only deduce type filters for these nodes
+        case exp = node.exp
+        when Var, IsA, RespondsTo, Not
+          @type_filters = type_filters.not
+          return false
+        end
       end
 
+      @type_filters = nil
+
       false
     end