Improve some parse errors

src/aeso_parse_lib.erl

@@ -15,6 +15,8 @@
          many/1, many1/1, sep/2, sep1/2,
          infixl/2, infixr/2]).
 
+-export([current_file/0, set_current_file/1]).
+
 %% -- Types ------------------------------------------------------------------
 
 -export_type([parser/1, parser_expr/1, pos/0, token/0, tokens/0]).
@@ -159,7 +161,7 @@ layout() -> ?layout.
 -spec parse(parser(A), tokens()) -> {ok, A} | {error, term()}.
 parse(P, S) ->
   case parse1(apply_p(P, fun(X) -> {return_plus, X, {fail, no_error}} end), S) of
-    {[], {Pos, Err}} -> {error, {Pos, parse_error, flatten_error(Err)}};
+    {[], {Pos, Err}} -> {error, {add_current_file(Pos), parse_error, flatten_error(Err)}};
     {[A], _}         -> {ok, A};
     {As, _}          -> {error, {{1, 1}, ambiguous_parse, As}}
   end.
@@ -289,7 +291,7 @@ parse1({tok_bind, Map}, Ts, Acc, Err) ->
                     %%            y + y)(4)
                     case maps:get(vclose, Map, '$not_found') of
                         '$not_found' ->
-                            {Acc, unexpected_token_error(Ts, T)};
+                            {Acc, unexpected_token_error(Ts, maps:keys(Map), T)};
                         F ->
                             VClose = {vclose, pos(T)},
                             Ts2    = pop_layout(VClose, Ts#ts{ last = VClose }),
@@ -333,7 +335,45 @@ mk_error(Ts, Err) ->
 
 -spec unexpected_token_error(#ts{}, token()) -> error().
 unexpected_token_error(Ts, T) ->
-    mk_error(Ts, io_lib:format("Unexpected token ~p", [tag(T)])).
+    unexpected_token_error(Ts, [], T).
+
+unexpected_token_error(Ts, Expect, {Tag, _}) when Tag == vclose; Tag == vsemi ->
+    Braces = [')', ']', '}'],
+    Fix    = case lists:filter(fun(T) -> lists:member(T, Braces) end, Expect) of
+                 []      -> " Probable causes:\n"
+                            "  - something is missing in the previous statement, or\n"
+                            "  - this line should be indented more.";
+                 [T | _] -> io_lib:format(" Did you forget a ~p?", [T])
+             end,
+    Msg = io_lib:format("Unexpected indentation.~s", [Fix]),
+    mk_error(Ts, Msg);
+unexpected_token_error(Ts, Expect, T) ->
+    ExpectCon = lists:member(con, Expect),
+    ExpectId  = lists:member(id,  Expect),
+    Fix = case T of
+              {id, _,  X}   when ExpectCon, hd(X) /= $_ -> io_lib:format(" Did you mean ~s?", [mk_upper(X)]);
+              {con, _, X}   when ExpectId               -> io_lib:format(" Did you mean ~s?", [mk_lower(X)]);
+              {qcon, _, Xs} when ExpectCon              -> io_lib:format(" Did you mean ~s?", [lists:last(Xs)]);
+              {qid, _,  Xs} when ExpectId               -> io_lib:format(" Did you mean ~s?", [lists:last(Xs)]);
+              _ -> ""
+          end,
+    mk_error(Ts, io_lib:format("Unexpected ~s.~s", [describe(T), Fix])).
+
+mk_upper([C | Rest]) -> string:to_upper([C]) ++ Rest.
+mk_lower([C | Rest]) -> string:to_lower([C]) ++ Rest.
+
+
+describe({id, _, X})     -> io_lib:format("identifier ~s", [X]);
+describe({con, _, X})    -> io_lib:format("identifier ~s", [X]);
+describe({qid, _, Xs})   -> io_lib:format("qualified identifier ~s", [string:join(Xs, ".")]);
+describe({qcon, _, Xs})  -> io_lib:format("qualified identifier ~s", [string:join(Xs, ".")]);
+describe({tvar, _, X})   -> io_lib:format("type variable ~s", [X]);
+describe({char, _, _})   -> "character literal";
+describe({string, _, _}) -> "string literal";
+describe({hex, _, _})    -> "integer literal";
+describe({int, _, _})    -> "integer literal";
+describe({bytes, _, _})  -> "bytes literal";
+describe(T)              -> io_lib:format("token '~s'", [tag(T)]).
 
 %% Get the next token from a token stream. Inserts layout tokens if necessary.
 -spec next_token(#ts{}) -> false | {token(), #ts{}}.
@@ -417,3 +457,13 @@ merge_with(Fun, Map1, Map2) ->
                         end, Map2, maps:to_list(Map1))
     end.
 
+%% Current source file
+current_file() ->
+    get('$current_file').
+
+set_current_file(File) ->
+    put('$current_file', File).
+
+add_current_file({L, C}) -> {current_file(), L, C};
+add_current_file(Pos)    -> Pos.
+

src/aeso_parser.erl

@@ -11,6 +11,7 @@
          type/1]).
 
 -include("aeso_parse_lib.hrl").
+-import(aeso_parse_lib, [current_file/0, set_current_file/1]).
 
 -type parse_result() :: aeso_syntax:ast() | none().
 
@@ -451,12 +452,6 @@ bracket_list(P) -> brackets(comma_sep(P)).
 -spec pos_ann(ann_line(), ann_col()) -> ann().
 pos_ann(Line, Col) -> [{file, current_file()}, {line, Line}, {col, Col}].
 
-current_file() ->
-    get('$current_file').
-
-set_current_file(File) ->
-    put('$current_file', File).
-
 ann_pos(Ann) ->
     {proplists:get_value(file, Ann),
      proplists:get_value(line, Ann),

test/aeso_compiler_tests.erl

@@ -162,7 +162,16 @@ not_yet_compilable(aevm) -> [].
      end)()).
 
 failing_contracts() ->
-    [ ?TEST(name_clash,
+    %% Parse errors
+    [ ?TEST(field_parse_error,
+       [<<?Pos(5, 26)
+          "Cannot use nested fields or keys in record construction: p.x">>])
+    , ?TEST(vsemi,  [<<?Pos(3, 3) "Unexpected indentation. Did you forget a '}'?">>])
+    , ?TEST(vclose, [<<?Pos(4, 3) "Unexpected indentation. Did you forget a ']'?">>])
+    , ?TEST(indent_fail, [<<?Pos(3, 2) "Unexpected token 'entrypoint'.">>])
+
+    %% Type errors
+    , ?TEST(name_clash,
        [<<?Pos(14, 3)
           "Duplicate definitions of abort at\n"
           "  - (builtin location)\n"
@@ -444,9 +453,6 @@ failing_contracts() ->
           "The init function should return the initial state as its result and cannot read the state,\n"
           "but it calls\n"
           "  - state (at line 13, column 13)">>])
-    , ?TEST(field_parse_error,
-       [<<?Pos("field_parse_error", 5, 26)
-          "Cannot use nested fields or keys in record construction: p.x">>])
     , ?TEST(modifier_checks,
        [<<?Pos(11, 3)
           "The function all_the_things (at line 11, column 3) cannot be both public and private.">>,

test/contracts/indent_fail.aes

@@ -0,0 +1,3 @@
+contract IndentFail =
+  entrypoint twoSpace() = ()
+ entrypoint oneSpace() = ()

test/contracts/vclose.aes

@@ -0,0 +1,4 @@
+contract VClose =
+  entrypoint missing_bracket() =
+    let x = [1, 2, 3
+  entrypoint bar() = ()

test/contracts/vsemi.aes

@@ -0,0 +1,3 @@
+contract VSemi =
+  record missing_brace = { x : int
+  entrypoint foo() = ()