Merge pull request #489 from ferd/maybe_expr_unsupported

Add known problem for unsupported maybe expression

Author: erszcz

.github/workflows/build-and-test.yml

@@ -9,11 +9,11 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     name: Erlang ${{matrix.otp}}
     strategy:
       matrix:
-        otp: ['22.3.4.20', '23.3.4.7', '24.3.4.4']
+        otp: ['23.3.4.7', '24.3.4.4', '25.1.2']
     steps:
       - uses: actions/checkout@v2
       - uses: erlef/setup-beam@v1

.github/workflows/proptests.yml

@@ -9,7 +9,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     name: Erlang ${{matrix.otp}}
     strategy:
       matrix:

.github/workflows/publish-to-hex.yml

@@ -5,7 +5,7 @@ on:
 
 jobs:
   publish:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
       - name: Check Out

.github/workflows/self-check.yml

@@ -9,7 +9,7 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     name: Erlang ${{matrix.otp}}
     strategy:
       matrix:

Makefile

@@ -32,6 +32,8 @@
 .PHONY: all
 all: app escript
 
+ERL_OPTS = -enable-feature maybe_expr
+
 # Compilation
 
 erls = $(wildcard src/*.erl)
@@ -143,7 +145,7 @@ end
 endef
 
 eunit: compile-tests
-	erl -noinput -pa ebin -pa test -eval \
+	erl $(ERL_OPTS) -noinput -pa ebin -pa test -eval \
 	 '$(erl_run_eunit), halt().'
 
 cli-tests: bin/gradualizer test/arg.beam

rebar.config

@@ -4,7 +4,10 @@
           {deps,
            [
             {proper, {git, "https://github.com/proper-testing/proper.git", {branch, "master"}}}
-           ]}
+           ]},
+          %% see the maybe expression fail;
+          %% the VM also needs to be configured to load the module
+          {erl_opts, [{feature,maybe_expr,enable}]}
          ]}
  ]}.
 

src/gradualizer_fmt.erl

@@ -362,6 +362,12 @@ format_type_error({form_check_timeout, Form}, Opts) ->
                              [form_info(Form),
                               format_location(Form, verbose, Opts)])
        end]);
+format_type_error({unsupported_expression, Anno, Expr}, Opts) ->
+    io_lib:format(
+      "~sThe ~s expression~s is not supported yet~n",
+      [format_location(Anno, brief, Opts),
+       atom_to_list(element(1, Expr)),
+       format_location(Anno, verbose, Opts)]);
 format_type_error({Location, Module, ErrorDescription}, Opts)
   when is_integer(Location) orelse is_tuple(Location),
        is_atom(Module) ->

src/typechecker.erl

@@ -1903,7 +1903,12 @@ do_type_check_expr(Env, {'try', _, Block, CaseCs, CatchCs, AfterBlock}) ->
           end,
     {normalize({type, erl_anno:new(0), union, [Ty, TyC, TyS]}, Env)
     ,VB
-    ,constraints:combine([Cs1,Cs2,Cs3,Cs4])}.
+    ,constraints:combine([Cs1,Cs2,Cs3,Cs4])};
+
+%% 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}).
 
 %% Helper for type_check_expr for funs
 -spec type_check_fun(env(), _) -> {type(), env(), constraints:constraints()}.

test/known_problems/should_pass/any_doesnt_have_type_none_should_pass.erl

@@ -1,5 +1,7 @@
 -module(any_doesnt_have_type_none_should_pass).
 
+-export([f/2]).
+
 -type type() :: abstract_type().
 
 -type abstract_type() :: af_tuple_type().

test/known_problems/should_pass/fun_subtyping.erl

@@ -1,6 +1,6 @@
 -module(fun_subtyping).
 
--compile([export_all, nowarn_export_all]).
+-export([return_fun_intersection/0]).
 
 -spec return_fun_intersection() -> fun((number()) -> number()).
 return_fun_intersection() -> fun number/1.