Correct handling of type names in contracts

Variables in contracts can either be true type variables or simply names for
types thet are defined in the 'when' clauses. Consider the following example:

-spec foo(X, Options) -> {ok, X} | error when Options :: [{atom(), boolean()}].

Here X is a true variable whereas Options is a name for a type that is defined
in the when clause.

'when' clauses may further use names on the right side. These were not treated
properly by Dialyzer and could be generalized to the term() type. This patch
fixes this issue.

A further issue is the treatment of true type variables, but this is left for
another patch.

1 files changed, 31 insertions, 0 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/results/contracts_with_subtypes b/lib/dialyzer/test/small_SUITE_data/results/contracts_with_subtypes
new file mode 100644
index 0000000000..8dc0361b0d
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/contracts_with_subtypes
@@ -0,0 +1,31 @@
+
+contracts_with_subtypes.erl:106: The call contracts_with_subtypes:rec_arg({'a','b'}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:107: The call contracts_with_subtypes:rec_arg({'b','a'}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:108: The call contracts_with_subtypes:rec_arg({'a',{'b','a'}}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:109: The call contracts_with_subtypes:rec_arg({'b',{'a','b'}}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:110: The call contracts_with_subtypes:rec_arg({'a',{'b',{'a','b'}}}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:111: The call contracts_with_subtypes:rec_arg({'b',{'a',{'b','a'}}}) breaks the contract (Arg) -> 'ok' when is_subtype(Arg,{'a',A} | {'b',B}), is_subtype(A,'a' | {'b',B}), is_subtype(B,'b' | {'a',A})
+contracts_with_subtypes.erl:142: The pattern 1 can never match the type binary() | string()
+contracts_with_subtypes.erl:145: The pattern 'alpha' can never match the type {'ok',X} | {'ok',X,binary() | string()}
+contracts_with_subtypes.erl:147: The pattern 42 can never match the type {'ok',_} | {'ok',_,binary() | string()}
+contracts_with_subtypes.erl:163: The pattern 'alpha' can never match the type {'ok',X}
+contracts_with_subtypes.erl:165: The pattern 42 can never match the type {'ok',X}
+contracts_with_subtypes.erl:183: The pattern 'alpha' can never match the type {'ok',X}
+contracts_with_subtypes.erl:185: The pattern 42 can never match the type {'ok',X}
+contracts_with_subtypes.erl:202: The pattern 1 can never match the type binary() | string()
+contracts_with_subtypes.erl:205: The pattern {'ok', _} can never match the type {'ok',X,binary() | string()}
+contracts_with_subtypes.erl:206: The pattern 'alpha' can never match the type {'ok',X,binary() | string()}
+contracts_with_subtypes.erl:207: The pattern {'ok', 42} can never match the type {'ok',X,binary() | string()}
+contracts_with_subtypes.erl:208: The pattern 42 can never match the type {'ok',X,binary() | string()}
+contracts_with_subtypes.erl:234: Function flat_ets_new_t/0 has no local return
+contracts_with_subtypes.erl:235: The call contracts_with_subtypes:flat_ets_new(12,[]) breaks the contract (Name,Options) -> atom() when is_subtype(Name,atom()), is_subtype(Options,[Option]), is_subtype(Option,'set' | 'ordered_set' | 'bag' | 'duplicate_bag' | 'public' | 'protected' | 'private' | 'named_table' | {'keypos',integer()} | {'heir',pid(),term()} | {'heir','none'} | {'write_concurrency',boolean()} | {'read_concurrency',boolean()} | 'compressed')
+contracts_with_subtypes.erl:23: Invalid type specification for function contracts_with_subtypes:extract2/0. The success typing is () -> 'something'
+contracts_with_subtypes.erl:261: Function factored_ets_new_t/0 has no local return
+contracts_with_subtypes.erl:262: The call contracts_with_subtypes:factored_ets_new(12,[]) breaks the contract (Name,Options) -> atom() when is_subtype(Name,atom()), is_subtype(Options,[Option]), is_subtype(Option,Type | Access | 'named_table' | {'keypos',Pos} | {'heir',Pid::pid(),HeirData} | {'heir','none'} | Tweaks), is_subtype(Type,type()), is_subtype(Access,access()), is_subtype(Tweaks,{'write_concurrency',boolean()} | {'read_concurrency',boolean()} | 'compressed'), is_subtype(Pos,pos_integer()), is_subtype(HeirData,term())
+contracts_with_subtypes.erl:77: The call contracts_with_subtypes:foo1(5) breaks the contract (Arg1) -> Res when is_subtype(Arg1,atom()), is_subtype(Res,atom())
+contracts_with_subtypes.erl:78: The call contracts_with_subtypes:foo2(5) breaks the contract (Arg1) -> Res when is_subtype(Arg1,Arg2), is_subtype(Arg2,atom()), is_subtype(Res,atom())
+contracts_with_subtypes.erl:79: The call contracts_with_subtypes:foo3(5) breaks the contract (Arg1) -> Res when is_subtype(Arg2,atom()), is_subtype(Arg1,Arg2), is_subtype(Res,atom())
+contracts_with_subtypes.erl:7: Invalid type specification for function contracts_with_subtypes:extract/0. The success typing is () -> 'something'
+contracts_with_subtypes.erl:80: The call contracts_with_subtypes:foo4(5) breaks the contract (Type) -> Type when is_subtype(Type,atom())
+contracts_with_subtypes.erl:81: The call contracts_with_subtypes:foo5(5) breaks the contract (Type::atom()) -> Type::atom()
+contracts_with_subtypes.erl:82: The call contracts_with_subtypes:foo6(5) breaks the contract (Type) -> Type when is_subtype(Type,atom())