From f347eaee9059fdda18cb8401bac1d72129b51d22 Mon Sep 17 00:00:00 2001
From: Ulf Norell <ulf.norell@gmail.com>
Date: Fri, 10 May 2019 14:04:01 +0200
Subject: [PATCH] Check for repeated argument names to functions

(PT-159592825)
---
 src/aeso_ast_infer_types.erl   | 13 ++++++++++++-
 test/aeso_compiler_tests.erl   |  2 ++
 test/contracts/type_errors.aes |  2 ++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/aeso_ast_infer_types.erl b/src/aeso_ast_infer_types.erl
index f4eaf63..3f65c9b 100644
--- a/src/aeso_ast_infer_types.erl
+++ b/src/aeso_ast_infer_types.erl
@@ -862,7 +862,8 @@ infer_letrec(Env, Defs) ->
     [print_typesig(S) || S <- TypeSigs],
     {TypeSigs, NewDefs}.
 
-infer_letfun(Env, {letfun, Attrib, {id, NameAttrib, Name}, Args, What, Body}) ->
+infer_letfun(Env, {letfun, Attrib, Fun = {id, NameAttrib, Name}, Args, What, Body}) ->
+    check_unique_arg_names(Fun, Args),
     ArgTypes  = [{ArgName, check_type(Env, arg_type(T))} || {arg, _, ArgName, T} <- Args],
     ExpectedType = check_type(Env, arg_type(What)),
     NewBody={typed, _, _, ResultType} = check_expr(bind_vars(ArgTypes, Env), Body, ExpectedType),
@@ -873,6 +874,13 @@ infer_letfun(Env, {letfun, Attrib, {id, NameAttrib, Name}, Args, What, Body}) ->
     {{Name, TypeSig},
      {letfun, Attrib, {id, NameAttrib, Name}, NewArgs, ResultType, NewBody}}.
 
+check_unique_arg_names(Fun, Args) ->
+    Name = fun({arg, _, {id, _, X}, _}) -> X end,
+    Names = lists:map(Name, Args),
+    Dups = lists:usort(Names -- lists:usort(Names)),
+    [ type_error({repeated_arg, Fun, Arg}) || Arg <- Dups ],
+    ok.
+
 print_typesig({Name, TypeSig}) ->
     ?PRINT_TYPES("Inferred ~s : ~s\n", [Name, pp(TypeSig)]).
 
@@ -1929,6 +1937,9 @@ pp_error({include, {string, Pos, Name}}) ->
 pp_error({namespace, _Pos, {con, Pos, Name}, _Def}) ->
     io_lib:format("Nested namespace not allowed\nNamespace '~s' at ~s not defined at top level.\n",
                   [Name, pp_loc(Pos)]);
+pp_error({repeated_arg, Fun, Arg}) ->
+    io_lib:format("Repeated argument ~s to function ~s (at ~s).\n",
+                  [Arg, pp(Fun), pp_loc(Fun)]);
 pp_error(Err) ->
     io_lib:format("Unknown error: ~p\n", [Err]).
 
diff --git a/test/aeso_compiler_tests.erl b/test/aeso_compiler_tests.erl
index dffb324..485793d 100644
--- a/test/aeso_compiler_tests.erl
+++ b/test/aeso_compiler_tests.erl
@@ -191,6 +191,8 @@ failing_contracts() ->
           "  - r' (at line 5, column 10)">>,
         <<"Repeated name x in pattern\n"
           "  x :: x (at line 26, column 7)">>,
+        <<"Repeated argument x to function repeated_arg (at line 44, column 12).">>,
+        <<"Repeated argument y to function repeated_arg (at line 44, column 12).">>,
         <<"No record type with fields y, z (at line 14, column 22)">>,
         <<"The field z is missing when constructing an element of type r2 (at line 15, column 24)">>,
         <<"Record type r2 does not have field y (at line 15, column 22)">>]}
diff --git a/test/contracts/type_errors.aes b/test/contracts/type_errors.aes
index d106686..ef4718e 100644
--- a/test/contracts/type_errors.aes
+++ b/test/contracts/type_errors.aes
@@ -40,3 +40,5 @@ contract Test =
 
   function type_error(r, x) =
     set_x(set_x(x, r), x)
+
+  function repeated_arg(x : int, y, x : string, y : bool) : string = x