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authorHans Bolinder <[email protected]>2016-11-29 09:37:21 +0100
committerHans Bolinder <[email protected]>2016-12-01 16:07:11 +0100
commit91048957f0681dba853f5720d3618aa1c5d0255e (patch)
tree6e15b3365bc2ea4b9d7042c1d023f71bb0002f2d /lib/stdlib/src
parentca29c37928ad36cf4270fb3edffc2cf9752f2ed9 (diff)
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stdilb: Check for bad type constraints in function types
The parser recognizes the 'is_subtype(V, T)' syntax for constraints, and of course the new 'V :: T' syntax, but other variants result in an error message. Up to now, the parser and linter have let badly formed constraints through, and relied upon Dialyzer to emit warnings. is_subtype/2 cannot easily be taken out from the parser. Not only would we need find a way to emit a (linter) warning, but there also needs to be an option for suppressing the linter warning as compilation with +warnings_as_errors has to work. (Notice that the abstract format representation for 'V :: T' is the same as for 'is_subtype(V, T)'.) This correction was triggered by an email from Robert, and Kostis created pull request 1214 to provide a fix. However, Kostis' fix disallowed is_subtype() altogether, which breaks backward compatibility. As of Erlang/OTP 19.0 (ticket OTP-11879), the 'is_subtype(V, T)' is no longer documented.
Diffstat (limited to 'lib/stdlib/src')
-rw-r--r--lib/stdlib/src/erl_parse.yrl36
1 files changed, 21 insertions, 15 deletions
diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 9cd95705af..a0bc21fbc5 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -33,7 +33,6 @@ list tail
list_comprehension lc_expr lc_exprs
binary_comprehension
tuple
-%struct
record_expr record_tuple record_field record_fields
map_expr map_tuple map_field map_field_assoc map_field_exact map_fields map_key
if_expr if_clause if_clauses case_expr cr_clause cr_clauses receive_expr
@@ -108,9 +107,8 @@ type_sig -> fun_type 'when' type_guards : {type, ?anno('$1'), bounded_fun,
type_guards -> type_guard : ['$1'].
type_guards -> type_guard ',' type_guards : ['$1'|'$3'].
-type_guard -> atom '(' top_types ')' : {type, ?anno('$1'), constraint,
- ['$1', '$3']}.
-type_guard -> var '::' top_type : build_def('$1', '$3').
+type_guard -> atom '(' top_types ')' : build_compat_constraint('$1', '$3').
+type_guard -> var '::' top_type : build_constraint('$1', '$3').
top_types -> top_type : ['$1'].
top_types -> top_type ',' top_types : ['$1'|'$3'].
@@ -268,7 +266,6 @@ expr_max -> binary : '$1'.
expr_max -> list_comprehension : '$1'.
expr_max -> binary_comprehension : '$1'.
expr_max -> tuple : '$1'.
-%%expr_max -> struct : '$1'.
expr_max -> '(' expr ')' : '$2'.
expr_max -> 'begin' exprs 'end' : {block,?anno('$1'),'$2'}.
expr_max -> if_expr : '$1'.
@@ -327,10 +324,6 @@ lc_expr -> binary '<=' expr : {b_generate,?anno('$2'),'$1','$3'}.
tuple -> '{' '}' : {tuple,?anno('$1'),[]}.
tuple -> '{' exprs '}' : {tuple,?anno('$1'),'$2'}.
-
-%%struct -> atom tuple :
-%% {struct,?anno('$1'),element(3, '$1'),element(3, '$2')}.
-
map_expr -> '#' map_tuple :
{map, ?anno('$1'),'$2'}.
map_expr -> expr_max '#' map_tuple :
@@ -1056,13 +1049,13 @@ build_typed_attribute({atom,Aa,Attr},_) ->
end.
build_type_spec({Kind,Aa}, {SpecFun, TypeSpecs})
- when (Kind =:= spec) or (Kind =:= callback) ->
+ when Kind =:= spec ; Kind =:= callback ->
NewSpecFun =
case SpecFun of
{atom, _, Fun} ->
{Fun, find_arity_from_specs(TypeSpecs)};
- {{atom,_, Mod}, {atom,_, Fun}} ->
- {Mod,Fun,find_arity_from_specs(TypeSpecs)}
+ {{atom, _, Mod}, {atom, _, Fun}} ->
+ {Mod, Fun, find_arity_from_specs(TypeSpecs)}
end,
{attribute,Aa,Kind,{NewSpecFun, TypeSpecs}}.
@@ -1076,11 +1069,24 @@ find_arity_from_specs([Spec|_]) ->
{type, _, 'fun', [{type, _, product, Args},_]} = Fun,
length(Args).
-build_def({var, A, '_'}, _Types) ->
+%% The 'is_subtype(V, T)' syntax is not supported as of Erlang/OTP
+%% 19.0, but is kept for backward compatibility.
+build_compat_constraint({atom, _, is_subtype}, [{var, _, _}=LHS, Type]) ->
+ build_constraint(LHS, Type);
+build_compat_constraint({atom, _, is_subtype}, [LHS, _Type]) ->
+ ret_err(?anno(LHS), "bad type variable");
+build_compat_constraint({atom, A, Atom}, _Types) ->
+ ret_err(A, io_lib:format("unsupported constraint ~w", [Atom])).
+
+build_constraint({atom, _, is_subtype}, [{var, _, _}=LHS, Type]) ->
+ build_constraint(LHS, Type);
+build_constraint({atom, A, Atom}, _Foo) ->
+ ret_err(A, io_lib:format("unsupported constraint ~w", [Atom]));
+build_constraint({var, A, '_'}, _Types) ->
ret_err(A, "bad type variable");
-build_def(LHS, Types) ->
+build_constraint(LHS, Type) ->
IsSubType = {atom, ?anno(LHS), is_subtype},
- {type, ?anno(LHS), constraint, [IsSubType, [LHS, Types]]}.
+ {type, ?anno(LHS), constraint, [IsSubType, [LHS, Type]]}.
lift_unions(T1, {type, _Aa, union, List}) ->
{type, ?anno(T1), union, [T1|List]};