fix: don't mistake __index for an incorrect method use

Fixes #680.
teal-language · Jul 17, 2023 · d4b1763 · d4b1763
1 parent 1001811
commit d4b1763
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Showing 3 changed files with 26 additions and 6 deletions.
diff --git a/spec/metamethods/index_spec.lua b/spec/metamethods/index_spec.lua
@@ -166,4 +166,18 @@ describe("metamethod __index", function()
    ]], {
       { y = 7, msg = "in assignment: argument 2: got string, expected number" }
    }))
+
+   it("passes regression test for #680", util.check([[
+      local record R
+        metamethod __index: function(self: R, key: string): any
+      end
+
+      function R:brackets()
+        print(self["x"])
+      end
+
+      function R:dot()
+        print(self.x)
+      end
+   ]]))
 end)
diff --git a/tl.lua b/tl.lua
@@ -7546,9 +7546,12 @@ tl.type_check = function(ast, opts)
                   local f = is_func and func or func.types[i]
                   if f.is_method and not is_method then
                      if args[1] and is_a(args[1], f.args[1]) then
-                        local receiver_is_typetype = where.e1.e1 and where.e1.e1.type and where.e1.e1.type.resolved and where.e1.e1.type.resolved.typename == "typetype"
-                        if not receiver_is_typetype then
-                           node_warning("hint", where, "invoked method as a regular function: consider using ':' instead of '.'")
+
+                        if where.kind == "op" and where.op.op == "@funcall" then
+                           local receiver_is_typetype = where.e1.e1 and where.e1.e1.type and where.e1.e1.type.resolved and where.e1.e1.type.resolved.typename == "typetype"
+                           if not receiver_is_typetype then
+                              node_warning("hint", where, "invoked method as a regular function: consider using ':' instead of '.'")
+                           end
                         end
                      else
                         return node_error(where, "invoked method as a regular function: use ':' instead of '.'")

diff --git a/tl.tl b/tl.tl
@@ -7546,9 +7546,12 @@ tl.type_check = function(ast: Node, opts: TypeCheckOptions): Result, string
                   local f = is_func and func or func.types[i]
                   if f.is_method and not is_method then
                      if args[1] and is_a(args[1], f.args[1]) then
-                        local receiver_is_typetype = where.e1.e1 and where.e1.e1.type and where.e1.e1.type.resolved and where.e1.e1.type.resolved.typename == "typetype"
-                        if not receiver_is_typetype then
-                           node_warning("hint", where, "invoked method as a regular function: consider using ':' instead of '.'")
+                        -- a non-"@funcall" `where` means a synthesized call, e.g. from a metamethod
+                        if where.kind == "op" and where.op.op == "@funcall" then
+                           local receiver_is_typetype = where.e1.e1 and where.e1.e1.type and where.e1.e1.type.resolved and where.e1.e1.type.resolved.typename == "typetype"
+                           if not receiver_is_typetype then
+                              node_warning("hint", where, "invoked method as a regular function: consider using ':' instead of '.'")
+                           end
                         end
                      else
                         return node_error(where, "invoked method as a regular function: use ':' instead of '.'")