Merge pull request #571 from erszcz/skip-maybe

Skip functions using maybe expr, don't crash on maybe ... else

Author: erszcz

src/typechecker.erl

@@ -2215,8 +2215,12 @@ do_type_check_expr(Env, {'try', _, Block, CaseCs, CatchCs, AfterBlock}) ->
 
 %% Maybe - value-based error handling expression
 %% See https://www.erlang.org/eeps/eep-0049
-do_type_check_expr(_Env, {'maybe', Anno, [{maybe_match, _, _LHS, _RHS}]} = MaybeExpr) ->
-    erlang:throw({unsupported_expression, Anno, MaybeExpr}).
+do_type_check_expr(Env, {'maybe', _, _}) ->
+    %% TODO: handle maybe expr properly
+    {type(any), Env};
+do_type_check_expr(Env, {'maybe', _, _, {'else', _, _}}) ->
+    %% TODO: handle maybe expr properly
+    {type(any), Env}.
 
 %% Helper for type_check_expr for funs
 -spec type_check_fun(env(), _) -> {type(), env()}.
@@ -3073,7 +3077,16 @@ do_type_check_expr_in(Env, ResTy, {'try', _, Block, CaseCs, CatchCs, AfterBlock}
     end,
     %% no variable bindings are propagated from a try expression
     %% as that would be "unsafe"
-    Env.
+    Env;
+
+%% Maybe - value-based error handling expression
+%% See https://www.erlang.org/eeps/eep-0049
+do_type_check_expr_in(_Env, _ResTy, {'maybe', _, _}) ->
+    %% TODO: handle maybe expr properly
+    erlang:throw({skip, maybe_expr_not_supported});
+do_type_check_expr_in(_Env, _ResTy, {'maybe', _, _, {'else', _, _}}) ->
+    %% TODO: handle maybe expr properly
+    erlang:throw({skip, maybe_expr_not_supported}).
 
 -spec type_check_arith_op_in(env(), type(), _, _, _, _) -> env().
 type_check_arith_op_in(Env, ResTy, Op, P, Arg1, Arg2) ->

test/known_problems/should_fail/maybe_expr_should_fail.erl

@@ -0,0 +1,46 @@
+-module(maybe_expr_should_fail).
+
+-ifdef(OTP_RELEASE).
+-if(?OTP_RELEASE >= 25).
+-if(?FEATURE_AVAILABLE(maybe_expr)).
+
+-feature(maybe_expr, enable).
+
+-export([check1/0, check2/0]).
+-export([infer1/0, infer2/1]).
+
+-spec check1() -> integer().
+check1() ->
+    maybe
+        ok ?= ok,
+        "one"
+    end.
+
+-spec check2() -> integer().
+check2() ->
+    maybe
+        ok ?= not_ok,
+        one
+    else
+        _ -> "two"
+    end.
+
+-spec infer1() -> integer().
+infer1() ->
+    R = maybe
+        ok ?= ok
+    end,
+    R.
+
+-spec infer2(string()) -> integer().
+infer2(Val) ->
+    R = maybe
+        ok ?= Val
+    else
+        _ -> ok
+    end,
+    R.
+
+-endif. %% FEATURE_AVAILABLE
+-endif. %% OTP >= 25
+-endif. %% OTP_RELEASE

test/known_problems/should_pass/maybe_expr.erl

@@ -3,9 +3,9 @@
 -export([f/1]).
 
 -type t1() :: binary().
--type maybe(T) :: undefined | T.
+-type option(T) :: undefined | T.
 
--spec f(maybe(t1())) -> ok | error | other.
+-spec f(option(t1())) -> ok | error | other.
 f(T) ->
     case T of
         undefined -> error;

test/should_pass/binary_literal_pattern.erl

@@ -0,0 +1,48 @@
+-module(maybe_expr_pass).
+
+-ifdef(OTP_RELEASE).
+-if(?OTP_RELEASE >= 25).
+-if(?FEATURE_AVAILABLE(maybe_expr)).
+
+-feature(maybe_expr, enable).
+
+-export([check1/0, check2/0]).
+-export([infer1/0, infer2/1]).
+
+-spec check1() -> integer().
+check1() ->
+    maybe
+        ok ?= ok,
+        1
+    end.
+
+-spec check2() -> integer().
+check2() ->
+    maybe
+        ok ?= not_ok,
+        1
+    else
+        _ -> 2
+    end.
+
+-spec infer1() -> integer().
+infer1() ->
+    R = maybe
+        ok ?= ok,
+        1
+    end,
+    R.
+
+-spec infer2(string()) -> {ok, string()} | error.
+infer2(Val) ->
+    R = maybe
+        "ok" ?= Val,
+        {ok, Val}
+    else
+        _ -> error
+    end,
+    R.
+
+-endif. %% FEATURE_AVAILABLE
+-endif. %% OTP >= 25
+-endif. %% OTP_RELEASE