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[Super errors] Better missing param msg #2554

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Merged
merged 2 commits into from
Feb 28, 2018
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[Super errors] Better missing param msg #2554

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9edc9b3
[Super errors] Better missing param msg
chenglou Feb 28, 2018
fec02d0
Clean up code
chenglou Feb 28, 2018
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133 changes: 71 additions & 62 deletions jscomp/super_errors/super_typecore.ml
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Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,10 @@ let show_extra_help ppf env trace = begin
| _ -> ();
end

(* given type1 is foo => bar => baz and type 2 is bar => baz, return Some(foo) *)
(* given type1 is foo => bar => baz(qux) and type 2 is bar => baz(qux), return Some(foo) *)
let rec collect_missing_arguments env type1 type2 = match type1 with
| {desc=Tarrow (label, argtype, typ, _)} when Ctype.equal env true [typ] [type2] ->
(* why do we use Ctype.matches here? Please see https://github.com/BuckleScript/bucklescript/pull/2554 *)
| {desc=Tarrow (label, argtype, typ, _)} when Ctype.matches env typ type2 ->
Some [(label, argtype)]
| {desc=Tarrow (label, argtype, typ, _)} -> begin
match collect_missing_arguments env typ type2 with
Expand Down Expand Up @@ -100,6 +101,71 @@ let check_bs_arity_mismatch ppf trace =
false in
ignore (traverse trace)

let print_expr_type_clash env trace ppf =
(* this is the most frequent error. Do whatever we can to provide specific
guidance to this generic error before giving up *)
if Super_reason_react.state_escape_scope trace then
fprintf ppf "@[<v>\
@[@{<info>Is this a ReasonReact reducerComponent or component with retained props?@}@ \
If so, is the type for state, retained props or action declared _after_ the component declaration?@ \
Moving these types above the component declaration should resolve this!@]@,@,\
@[@{<info>Here's the original error message@}@]@,\
@]"
else if Super_reason_react.is_array_wanted_reactElement trace then
fprintf ppf "@[<v>\
@[@{<info>Are you passing an array as a ReasonReact DOM (lower-case) component's children?@}@ If not, disregard this.@ \
If so, please use `ReasonReact.createDomElement`:@ https://reasonml.github.io/reason-react/docs/en/children.html@]@,@,\
@[@{<info>Here's the original error message@}@]@,\
@]";
begin
let bottom_aliases_result = bottom_aliases trace in
let missing_arguments = match bottom_aliases_result with
| Some (actual, expected) -> collect_missing_arguments env actual expected
| None -> assert false
in
let print_arguments =
Format.pp_print_list
~pp_sep:(fun ppf _ -> fprintf ppf ",@ ")
(fun ppf (label, argtype) ->
if label = "" then fprintf ppf "@[%a@]" type_expr argtype
else fprintf ppf "@[(~%s: %a)@]" label type_expr argtype
)
in
begin match missing_arguments with
| Some [singleArgument] ->
(* btw, you can't say "final arguments". Intermediate labeled
arguments might be the ones missing *)
fprintf ppf "@[@{<info>This call is missing an argument@} of type@ %a@]"
print_arguments [singleArgument]
| Some arguments ->
fprintf ppf "@[<hv>@{<info>This call is missing arguments@} of type:@ %a@]"
print_arguments arguments
| None ->
let missing_parameters = match bottom_aliases_result with
| Some (actual, expected) -> collect_missing_arguments env expected actual
| None -> assert false
in
begin match missing_parameters with
| Some [singleParameter] ->
fprintf ppf "@[This value might need to be @{<info>wrapped in a function@ that@ takes@ an@ extra@ parameter@}@ of@ type@ %a@]@,@,"
print_arguments [singleParameter];
fprintf ppf "@[@{<info>Here's the original error message@}@]@,"
| Some arguments ->
fprintf ppf "@[This value seems to @{<info>need to be wrapped in a function that takes extra@ arguments@}@ of@ type:@ @[<hv>%a@]@]@,@,"
print_arguments arguments;
fprintf ppf "@[@{<info>Here's the original error message@}@]@,"
| None -> ()
end;
(* final fallback: show the generic type mismatch error *)
check_bs_arity_mismatch ppf trace;
super_report_unification_error ppf env trace
(function ppf ->
fprintf ppf "This has type:")
(function ppf ->
fprintf ppf "But somewhere wanted:");
show_extra_help ppf env trace;
end;
end
(* taken from https://github.com/BuckleScript/ocaml/blob/d4144647d1bf9bc7dc3aadc24c25a7efa3a67915/typing/typecore.ml#L3769 *)
(* modified branches are commented *)
let report_error env ppf = function
Expand Down Expand Up @@ -137,66 +203,9 @@ let report_error env ppf = function
(Ident.name id)
| Expr_type_clash trace ->
(* modified *)
(* this is the most frequent error. Do whatever we can to provide specific
guidance to this generic error before giving up *)
if Super_reason_react.state_escape_scope trace then
fprintf ppf "@[<v>\
@[@{<info>Is this a ReasonReact reducerComponent or component with retained props?@}@ \
If so, is the type for state, retained props or action declared _after_ the component declaration?@ \
Moving these types above the component declaration should resolve this!@]@,@,\
@[@{<info>Here's the original error message@}@]@,\
@]"
else if Super_reason_react.is_array_wanted_reactElement trace then
fprintf ppf "@[<v>\
@[@{<info>Are you passing an array as a ReasonReact DOM (lower-case) component's children?@}@ If not, disregard this.@ \
If so, please use `ReasonReact.createDomElement`:@ https://reasonml.github.io/reason-react/docs/en/children.html@]@,@,\
@[@{<info>Here's the original error message@}@]@,\
@]";
begin
let bottom_aliases_result = bottom_aliases trace in
let missing_arguments = match bottom_aliases_result with
| Some (actual, expected) -> collect_missing_arguments env actual expected
| None -> assert false
in
let print_arguments =
Format.pp_print_list
~pp_sep:(fun ppf _ -> fprintf ppf ",@ ")
(fun ppf (label, argtype) ->
if label = "" then fprintf ppf "@[%a@]" type_expr argtype
else fprintf ppf "@[(~%s: %a)@]" label type_expr argtype
)
in
begin match missing_arguments with
| Some [singleArgument] ->
fprintf ppf "@[@{<info>This call is missing a final argument@} of type@ %a@]"
print_arguments [singleArgument]
| Some arguments ->
fprintf ppf "@[<hv>@{<info>This call is missing final arguments@} of type:@ %a@]"
print_arguments arguments
| None ->
let missing_parameters = match bottom_aliases_result with
| Some (actual, expected) -> collect_missing_arguments env expected actual
| None -> assert false
in
begin match missing_parameters with
| Some [singleParameter] ->
fprintf ppf "@[This value seems to @{<info>need to be wrapped in a function@ that@ takes@ an@ extra@ argument@}@ of@ type@ %a@]"
print_arguments [singleParameter]
| Some arguments ->
fprintf ppf "@[This value seems to @{<info>need to be wrapped in a function that takes extra@ arguments@}@ of@ type:@ @[<hv>%a@]@]"
print_arguments arguments
| None ->
(* final fallback: show the generic type mismatch error *)
check_bs_arity_mismatch ppf trace;
super_report_unification_error ppf env trace
(function ppf ->
fprintf ppf "This has type:")
(function ppf ->
fprintf ppf "But somewhere wanted:");
show_extra_help ppf env trace;
end;
end;
end
fprintf ppf "@[<v>";
print_expr_type_clash env trace ppf;
fprintf ppf "@]"
| Apply_non_function typ ->
(* modified *)
reset_and_mark_loops typ;
Expand Down