Add tests for __call metamethod

docs/pages/overview.md

@@ -1328,6 +1328,7 @@ Complete list of metamethods that can be defined for records:
 | `__index`        | `a[b]`{:.language-nelua}    | indexing | array index                            |
 | `__atindex`      | `a[b]`{:.language-nelua}    | indexing | array index via reference              |
 | `__tostring`     | tostring(a)                 | cast     | explicit/implicit cast to string       |
+| `__call`         | `a(...)`{:.language-nelua}  | call     | call a record                          |
 | `__convert`      |                             | cast     | implicit cast from anything            |
 | `__gc`           |                             | gc       | called when collected by the GC        |
 | `__close`        |                             | close    | called when `<close>` variables goes out of scope |

lualib/nelua/analyzer.lua

@@ -1318,11 +1318,10 @@ local function visitor_Call(context, node, argnodes, calleetype, calleesym, call
   local attr = node.attr
   if calleetype then
     local sideeffect
-    local origintype = calleetype
-    if calleetype.is_record and calleetype.metafields.__call ~= nil then
+    if calleetype.is_record and calleetype.metafields.__call then
       calleetype = calleetype.metafields.__call.type
       if not calleetype.is_procedure then
-        node:raisef("invalid metamethod __call in '%s'", calleetype)
+        node:raisef("in record call: expected meta field '__call' to be a procedure but is of type '%s'", calleetype)
       end
       attr.ismetacall = true
       calleeobjnode = node[2]

spec/analyzer_spec.lua

@@ -1306,6 +1306,12 @@ it("records metamethods", function()
     r[0] = x
     local len = #r
   ]])
+  expect.analyze_error([[
+    local R = @record{}
+    global R.__call: integer = 1
+    local r: R
+    r()
+  ]], "expected meta field '__call' to be a procedure")
   expect.analyze_error([[
     local R = @record{}
     function R:__atindex(x: integer): integer return 0 end

spec/cgenerator_spec.lua

@@ -2557,6 +2557,13 @@ it("record metametods", function()
     assert(3 == a)
     assert(0 ~= a)
   ]])
+
+  expect.run_c([[
+    local Foo = @record{value: number}
+    function Foo:__call(a: number, b: number): number return a + b + self.value end
+    local foo: Foo = {1}
+    assert(foo(2, 3) == 6)
+  ]])
 end)
 
 it("record operator overloading", function()