From 1001811eca92496e1b4d533c72587db5cf65a148 Mon Sep 17 00:00:00 2001
From: Hisham Muhammad <hisham@gobolinux.org>
Date: Sun, 16 Jul 2023 17:21:43 -0300
Subject: [PATCH] fix: when parsing vararg arguments, don't pollute base types

Fixes #679.
---
 spec/declaration/local_function_spec.lua |  9 ++++++-
 tl.lua                                   | 32 +++++++++++-----------
 tl.tl                                    | 34 +++++++++++++-----------
 3 files changed, 43 insertions(+), 32 deletions(-)

diff --git a/spec/declaration/local_function_spec.lua b/spec/declaration/local_function_spec.lua
index a6e168131..49bda904f 100644
--- a/spec/declaration/local_function_spec.lua
+++ b/spec/declaration/local_function_spec.lua
@@ -102,6 +102,7 @@ describe("local function", function()
 
       it("vararg can only be the last argument", util.check_syntax_error([[
          local f: function(...: string, number): boolean
+         local g: function(string, string..., number): boolean
 
          f = function(...: string, a: number): boolean
             return #select(1, ...) == a
@@ -109,8 +110,14 @@ describe("local function", function()
          local ok = f(3, "abc")
       ]], {
          { y = 1, msg = "'...' can only be last argument" },
-         { y = 3, msg = "'...' can only be last argument" },
+         { y = 2, msg = "'...' can only be last argument" },
+         { y = 4, msg = "'...' can only be last argument" },
       }))
+
+      it("does not get multiple uses of base types confused (regression test for #679)", util.check([[
+         local f: function(x: number, s: string, string...): boolean
+         local g: function(x: number, s: string, ...: string): boolean
+      ]]))
    end)
 
    it("declaration", util.check([[
diff --git a/tl.lua b/tl.lua
index f0038cc92..e4d28da07 100644
--- a/tl.lua
+++ b/tl.lua
@@ -2324,6 +2324,12 @@ parse_argument_list = function(ps, i)
    return i, node
 end
 
+
+
+
+
+
+
 local function parse_argument_type(ps, i)
    local is_va = false
    local argument_name = nil
@@ -2345,33 +2351,29 @@ local function parse_argument_type(ps, i)
          i = i + 1
          is_va = true
       end
-
-      typ.is_va = is_va
    end
 
    if argument_name == "self" then
       typ.is_self = true
    end
 
-   return i, typ, 0
+   return i, { i = i, type = typ, is_va = is_va }, 0
 end
 
 parse_argument_type_list = function(ps, i)
+   local tvs = {}
+   i = parse_bracket_list(ps, i, tvs, "(", ")", "sep", parse_argument_type)
    local list = new_type(ps, i, "tuple")
-   i = parse_bracket_list(ps, i, list, "(", ")", "sep", parse_argument_type)
-
-   if list[#list] then
-      for l = 1, #list - 1 do
-         if list[l].is_va then
-            list[l].is_va = nil
-            fail(ps, i, "'...' can only be last argument")
-         end
-      end
-      if list[#list].is_va then
-         list[#list].is_va = nil
-         list.is_va = true
+   local n = #tvs
+   for l, tv in ipairs(tvs) do
+      list[l] = tv.type
+      if tv.is_va and l < n then
+         fail(ps, tv.i, "'...' can only be last argument")
       end
    end
+   if tvs[n] and tvs[n].is_va then
+      list.is_va = true
+   end
    return i, list
 end
 
diff --git a/tl.tl b/tl.tl
index fabd0aff8..6c39e27e3 100644
--- a/tl.tl
+++ b/tl.tl
@@ -2324,7 +2324,13 @@ parse_argument_list = function(ps: ParseState, i: integer): integer, Node
    return i, node
 end
 
-local function parse_argument_type(ps: ParseState, i: integer): integer, Type, integer
+local record TypeAndVararg
+   i: integer
+   type: Type
+   is_va: boolean
+end
+
+local function parse_argument_type(ps: ParseState, i: integer): integer, TypeAndVararg, integer
    local is_va = false
    local argument_name: string = nil
    if ps.tokens[i].kind == "identifier" and ps.tokens[i + 1].tk == ":" then
@@ -2345,33 +2351,29 @@ local function parse_argument_type(ps: ParseState, i: integer): integer, Type, i
          i = i + 1
          is_va = true
       end
-      -- HACK: we're storing the attribute in the wrong node during the iteration...
-      typ.is_va = is_va
    end
 
    if argument_name == "self" then
       typ.is_self = true
    end
 
-   return i, typ, 0
+   return i, { i = i, type = typ, is_va = is_va }, 0
 end
 
 parse_argument_type_list = function(ps: ParseState, i: integer): integer, Type
+   local tvs: {TypeAndVararg} = {}
+   i = parse_bracket_list(ps, i, tvs, "(", ")", "sep", parse_argument_type)
    local list = new_type(ps, i, "tuple")
-   i = parse_bracket_list(ps, i, list, "(", ")", "sep", parse_argument_type)
-   -- HACK: ...and then cleaning it up and setting in the right node
-   if list[#list] then
-      for l = 1, #list - 1 do
-         if list[l].is_va then
-            list[l].is_va = nil
-            fail(ps, i, "'...' can only be last argument")
-         end
-      end
-      if list[#list].is_va then
-         list[#list].is_va = nil
-         list.is_va = true
+   local n = #tvs
+   for l, tv in ipairs(tvs) do
+      list[l] = tv.type
+      if tv.is_va and l < n then
+         fail(ps, tv.i, "'...' can only be last argument")
       end
    end
+   if tvs[n] and tvs[n].is_va then
+      list.is_va = true
+   end
    return i, list
 end