From 91048957f0681dba853f5720d3618aa1c5d0255e Mon Sep 17 00:00:00 2001 From: Hans Bolinder Date: Tue, 29 Nov 2016 09:37:21 +0100 Subject: 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. --- erts/doc/src/absform.xml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'erts/doc/src') diff --git a/erts/doc/src/absform.xml b/erts/doc/src/absform.xml index ab00d47425..fe8e3b30e7 100644 --- a/erts/doc/src/absform.xml +++ b/erts/doc/src/absform.xml @@ -886,7 +886,7 @@ Rep(Fc) = [Rep(C_1), ..., Rep(C_k)].

- If C is a constraint is_subtype(V, T) or V :: T, + If C is a constraint V :: T, where V is a type variable and T is a type, then Rep(C) = {type,LINE,constraint,[{atom,LINE,is_subtype},[Rep(V),Rep(T)]]}. -- cgit v1.2.3