From 181d2a546798ccc10ae3e61383e86e0891921ec5 Mon Sep 17 00:00:00 2001
From: Hisham Muhammad <hisham@gobolinux.org>
Date: Wed, 7 Aug 2024 17:09:14 -0300
Subject: [PATCH] fix: localizing a record does not make the new local a type

This allows for a pattern where we can localize a record
and load and alternative implementation on top of it.

Fixes #759.
---
 spec/call/record_method_spec.lua |  5 +++--
 spec/declaration/local_spec.lua  | 13 +++++++++++++
 spec/stdlib/require_spec.lua     | 27 +++++++++++++++++++++++++++
 tl.lua                           |  6 +++++-
 tl.tl                            |  6 +++++-
 5 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/spec/call/record_method_spec.lua b/spec/call/record_method_spec.lua
index 0e91056c1..5e000dc01 100644
--- a/spec/call/record_method_spec.lua
+++ b/spec/call/record_method_spec.lua
@@ -204,8 +204,9 @@ describe("record method call", function()
          end
          m.a.add(first)
       ]], {
-         -- FIXME this warning needs to go away when we detect that "m.a" and "first" are not the same
-         { y = 14, msg = "invoked method as a regular function: consider using ':' instead of '.'" }
+         -- FIXME these warnings need to go away when we detect that the arities are correct
+         { y = 10, msg = "invoked method as a regular function: consider using ':' instead of '.'" },
+         { y = 14, msg = "invoked method as a regular function: consider using ':' instead of '.'" },
       }, {}))
 
       it("for function declared in record body with self as different type from receiver", util.check_warnings([[
diff --git a/spec/declaration/local_spec.lua b/spec/declaration/local_spec.lua
index 932b11167..044d7a47a 100644
--- a/spec/declaration/local_spec.lua
+++ b/spec/declaration/local_spec.lua
@@ -460,6 +460,19 @@ describe("local", function()
 
             local b <total>: A = { v = 10 }
          ]]))
+
+         it("localizing a record does not make the new local a type (#759)", util.check([[
+            local record k
+            end
+
+            local kk: k = {}
+
+            local k = k
+
+            k = {}
+
+            kk = {}
+         ]]))
       end)
 
       describe("<close>", function()
diff --git a/spec/stdlib/require_spec.lua b/spec/stdlib/require_spec.lua
index 5ba6d8b89..d376c6c67 100644
--- a/spec/stdlib/require_spec.lua
+++ b/spec/stdlib/require_spec.lua
@@ -1249,4 +1249,31 @@ describe("require", function()
          { filename = "main.tl", x = 30, y = 1, msg = "require() in type declarations cannot be part of larger expressions" }
       }, result.syntax_errors)
    end)
+
+   it("can localize a record and load and alternative implementation (#759)", function ()
+      util.mock_io(finally, {
+         ["my-lua-utf8.tl"] = [[
+            local record my_lua_utf8
+            end
+
+            return my_lua_utf8
+         ]],
+         ["main.tl"] = [[
+            local type Utf8 = utf8
+            local utf8: Utf8 = utf8
+            if not utf8 then
+               local ok, lutf8 = pcall(require, 'my-lua-utf8') as (boolean, Utf8)
+               if ok then
+                  utf8 = lutf8
+               end
+            end
+            print(utf8.charpattern)
+         ]],
+      })
+      local result, err = tl.process("main.tl")
+
+      assert.same({}, result.syntax_errors)
+      assert.same({}, result.type_errors)
+   end)
+
 end)
diff --git a/tl.lua b/tl.lua
index 1cdf889a7..db6f1e6de 100644
--- a/tl.lua
+++ b/tl.lua
@@ -6979,7 +6979,7 @@ do
          local scope = self.st[i]
          local var = scope.vars[name]
          if var then
-            if use == "lvalue" and var.is_narrowed then
+            if use == "lvalue" and var.is_narrowed and var.is_narrowed ~= "localizing" then
                if var.narrowed_from then
                   var.used = true
                   return { t = var.narrowed_from, attribute = var.attribute }, i, var.attribute
@@ -10595,6 +10595,10 @@ self:expand_type(node, values, elements) })
          t.inferred_len = nil
       elseif t.typename == "nominal" then
          self:resolve_nominal(t)
+         local rt = t.resolved
+         if rt.typename == "typedecl" then
+            t.resolved = rt.def
+         end
       end
 
       return ok, t, infertype ~= nil
diff --git a/tl.tl b/tl.tl
index 528550a1e..b3b7a7623 100644
--- a/tl.tl
+++ b/tl.tl
@@ -6979,7 +6979,7 @@ do
          local scope = self.st[i]
          local var = scope.vars[name]
          if var then
-            if use == "lvalue" and var.is_narrowed then
+            if use == "lvalue" and var.is_narrowed and var.is_narrowed ~= "localizing" then
                if var.narrowed_from then
                   var.used = true
                   return { t = var.narrowed_from, attribute = var.attribute }, i, var.attribute
@@ -10595,6 +10595,10 @@ do
          t.inferred_len = nil
       elseif t is NominalType then
          self:resolve_nominal(t)
+         local rt = t.resolved
+         if rt is TypeDeclType then
+            t.resolved = rt.def
+         end
       end
 
       return ok, t, infertype ~= nil