From 0b1d1a591edbb56054ad2ce7f11119627aec5c82 Mon Sep 17 00:00:00 2001
From: Pietro Cerutti <gahr@gahr.ch>
Date: Thu, 21 Sep 2023 12:10:45 +0000
Subject: [PATCH] Disallow empty "or" type specifier

This fixes an inconsistency in the `or` type specifier when used with an empty argument list, whereas, contrary to how the `(or)` function is `#f`, the `(or)` type specifier is `*`.
---
 manual/Types    | 4 ++--
 scrutinizer.scm | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/manual/Types b/manual/Types
index f3fb6b7b..27ef0fc6 100644
--- a/manual/Types
+++ b/manual/Types
@@ -99,7 +99,7 @@ or {{:}} should follow the syntax given below:
 
 <table>  
 <tr><th>VALUETYPE</th><th>meaning</th></tr>
-<tr><td>{{(or VALUETYPE ...)}}</td><td>"union" or "sum" type</td></tr>
+<tr><td>{{(or VALUETYPE1 VALUETYPE2 ...)}}</td><td>"union" or "sum" type</td></tr>
 <tr><td>{{(not VALUETYPE)}}</td><td>non-matching type (*)</td></tr>
 <tr><td>{{(struct STRUCTURENAME)}}</td><td>record structure of given kind</td></tr>
 <tr><td>{{(procedure [NAME] (VALUETYPE ... [#!optional VALUETYPE ...] [#!rest [VALUETYPE]]) . RESULTS)}}</td><td>procedure type, optionally with name</td></tr>
@@ -241,7 +241,7 @@ Procedure types are assumed to be not referentially transparent and
 are assumed to possibly modify locally held state. Using the
 {{(... --> ...)}} syntax, you can declare a procedure to not modify
 local state, i.e. not causing any side-effects on local variables or
-data contain in local variables. This gives more opportunities for
+data contained in local variables. This gives more opportunities for
 optimization but may not be violated or the results are undefined.
 
 
diff --git a/scrutinizer.scm b/scrutinizer.scm
index cdf6f205..35f889e2 100644
--- a/scrutinizer.scm
+++ b/scrutinizer.scm
@@ -75,7 +75,7 @@
 ; result specifiers:
 ;
 ;   SPEC = * | (TYPE1 ...)
-;   TYPE = (or TYPE1 ...)
+;   TYPE = (or TYPE1 TYPE2 ...)
 ;        | (not TYPE)
 ;        | (struct NAME)
 ;        | (procedure [NAME] (TYPE1 ... [#!optional TYPE1 ...] [#!rest [TYPE | values]]) . RESULTS)
@@ -1911,6 +1911,7 @@
 		  v))
 	    ((eq? 'or (car t)) 
 	     (and (list? t)
+		  (not (null? (cdr t)))
 		  (let ((ts (map validate (cdr t))))
 		    (and (every identity ts)
 			 `(or ,@ts)))))
-- 
2.42.0