interfaces: enforce them to be abstract

Fixes #757.
teal-language · Aug 12, 2024 · 07c9ed4 · 07c9ed4
1 parent 2ec30ea
commit 07c9ed4
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Showing 3 changed files with 85 additions and 6 deletions.
diff --git a/spec/declaration/record_spec.lua b/spec/declaration/record_spec.lua
@@ -434,16 +434,79 @@ for i, name in ipairs({"records", "arrayrecords", "interfaces", "arrayinterfaces
          })[i]
       }))
 
-      it("can extend generic functions", util.check([[
-         local type foo = ]]..statement..[[ ]]..array(i, "{foo}")..[[
+      it("only records can have record methods", util.check_type_error([[
+         local ]]..statement..[[ Foo ]]..array(i, "{Foo}")..[[
+         end
+
+         function Foo:example(data: string)
+            print(data)
+         end
+      ]], {
+         ({
+            nil,
+            nil,
+            { msg = "interfaces are abstract" },
+            { msg = "interfaces are abstract" },
+         })[i]
+      }))
+
+      it("only records can have record functions", util.check_type_error([[
+         local ]]..statement..[[ Foo ]]..array(i, "{Foo}")..[[
+         end
+
+         function Foo.example(data: string)
+            print(data)
+         end
+      ]], {
+         ({
+            nil,
+            nil,
+            { msg = "interfaces are abstract" },
+            { msg = "interfaces are abstract" },
+         })[i]
+      }))
+
+      it("functions can be implemented in instances", util.check([[
+         local ]]..statement..[[ Foo ]]..array(i, "{Foo}")..[[
+            example: function(string)
+         end
+
+         local my_f: Foo = {}
+
+         function my_f.example(data: string)
+            print(data)
+         end
+      ]]))
+
+      it("methods can be implemented in instances", util.check([[
+         local ]]..statement..[[ Foo ]]..array(i, "{Foo}")..[[
+            example: function(Foo, string)
+         end
+
+         local my_f: Foo = {}
+
+         function my_f:example(data: string)
+            print(data)
+         end
+      ]]))
+
+      it("with implement generic functions", util.check_type_error([[
+         local type Foo = ]]..statement..[[ ]]..array(i, "{Foo}")..[[
             type bar = function<T>(T)
             example: bar<string>
          end
 
-         function foo.example(data: string)
+         function Foo.example(data: string)
             print(data)
          end
-      ]]))
+      ]], {
+         ({
+            nil,
+            nil,
+            { msg = "interfaces are abstract" },
+            { msg = "interfaces are abstract" },
+         })[i]
+      }))
 
       it("can use where with generic types", util.check([[
          local type Success = ]]..statement..[[<T> ]]..array(i, "is {integer}")..[[

diff --git a/tl.lua b/tl.lua
@@ -11518,7 +11518,15 @@ self:expand_type(node, values, elements) })
             local rets = children[4]
             assert(rets.typename == "tuple")
 
-            local rtype = self:to_structural(resolve_typedecl(children[1]))
+            local t = children[1]
+            local rtype = self:to_structural(resolve_typedecl(t))
+
+            do
+               local ok, err = ensure_not_abstract(t)
+               if not ok then
+                  self.errs:add(node, err)
+               end
+            end
 
             if self.feat_lax and rtype.typename == "unknown" then
                return

diff --git a/tl.tl b/tl.tl
@@ -11518,7 +11518,15 @@ do
             local rets = children[4]
             assert(rets is TupleType)
 
-            local rtype = self:to_structural(resolve_typedecl(children[1]))
+            local t = children[1]
+            local rtype = self:to_structural(resolve_typedecl(t))
+
+            do
+               local ok, err = ensure_not_abstract(t)
+               if not ok then
+                  self.errs:add(node, err)
+               end
+            end
 
             if self.feat_lax and rtype is UnknownType then
                return