Add validation of unit switch attributes.

We previously silently ignored unsupported attributes; now errors are
raised.

spicy/toolchain/src/compiler/visitors/validator.cc

@@ -11,6 +11,7 @@
 #include <hilti/ast/statements/switch.h>
 #include <hilti/base/logger.h>
 #include <hilti/base/result.h>
+#include <hilti/base/util.h>
 
 #include <spicy/ast/all.h>
 #include <spicy/ast/detail/visitor.h>
@@ -645,6 +646,15 @@ struct PreTransformVisitor : public hilti::visitor::PreOrder<void, PreTransformV
 
         if ( defaults > 1 )
             error("more than one default case", p);
+
+        if ( const auto& attrs = s.attributes() ) {
+            for ( const auto& attr : attrs->attributes() ) {
+                const auto& tag = attr.tag();
+
+                if ( tag != "&size" )
+                    error(fmt("attribute '%s' is not supported here", tag), p);
+            }
+        }
     }
 
     void operator()(const spicy::type::unit::item::Variable& v, position_t p) {

tests/Baseline/spicy.types.unit.switch-attributes-fail/output

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[error] <...>/switch-attributes-fail.spicy:9:5-11:27: attribute '&eod' is not supported here
+[error] <...>/switch-attributes-fail.spicy:9:5-11:27: attribute '&until' is not supported here
+[error] spicyc: aborting after errors

tests/spicy/types/unit/switch-attributes-fail.spicy

@@ -0,0 +1,12 @@
+# @TEST-EXEC-FAIL: spicyc -p %INPUT >output 2>&1
+# @TEST-EXEC: btest-diff output
+
+# @TEST-DOC: Tests that invalid switch attributes are rejected.
+
+module Mini;
+
+type X = unit {
+    switch ( 1 ) {
+        * -> : void;
+    } &eod &size=1 &until;
+};