Make skip productions behave like the production they are wrapping.

Closes #1586.

spicy/toolchain/include/compiler/detail/codegen/productions/skip.h

@@ -5,6 +5,7 @@
 #include <memory>
 #include <string>
 #include <utility>
+#include <vector>
 
 #include <hilti/ast/attribute.h>
 
@@ -26,11 +27,22 @@ class Skip : public Production {
     const auto& field() const { return _field; }
     const auto& ctor() const { return _ctor; }
 
-    bool isAtomic() const final { return true; };
-    bool isEodOk() const final { return _field->attributes()->has("&eod"); };
-    bool isLiteral() const final { return false; };
-    bool isNullable() const final { return false; };
-    bool isTerminal() const final { return true; };
+    bool isAtomic() const final { return _ctor ? _ctor->isAtomic() : true; };
+    bool isEodOk() const final { return _ctor ? _ctor->isEodOk() : _field->attributes()->has("&eod"); };
+    bool isLiteral() const final { return _ctor ? _ctor->isLiteral() : false; };
+    bool isNullable() const final { return _ctor ? _ctor->isNullable() : false; };
+    bool isTerminal() const final { return _ctor ? _ctor->isTerminal() : true; };
+    int64_t tokenID() const final { return _ctor ? _ctor->tokenID() : -1; };
+
+    std::vector<std::vector<Production*>> rhss() const final {
+        if ( _ctor )
+            return _ctor->rhss();
+        else
+            return {};
+    };
+
+
+    Expression* expression() const final { return _ctor ? _ctor->expression() : nullptr; }
 
     QualifiedType* type() const final { return _void; };
 

tests/Baseline/spicy.types.unit.skip-lahead/output

@@ -0,0 +1,8 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+foo::X {
+  xs: [
+    1
+    2
+    3
+  ]
+}

tests/spicy/types/unit/skip-lahead.spicy

@@ -0,0 +1,11 @@
+# @TEST-EXEC: printf '\x01\x02\x03.' | spicy-dump %INPUT >output
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Check that look-ahead works with skipped literals
+
+module foo;
+
+public type X = unit {
+    xs: uint8[];
+    : skip b".";
+};