Fix another assertion with anonymous struct constructor.

The struct type's ID could end up not making it across the
Spicy-to-HILTI boundary.

Closes #1234.

hilti/toolchain/include/ast/ctors/struct.h

@@ -55,7 +55,8 @@ class Struct : public NodeBase, public hilti::trait::isCtor {
         return {};
     }
 
-    void setType(const type::Struct& x) { children()[0] = x; }
+    void setType(const Type& t) { children()[0] = t; }
+    void setTypeID(ID id) { children()[0].as<Type>().setTypeID(std::move(id)); }
 
     bool operator==(const Struct& other) const { return fields() == other.fields(); }
 

hilti/toolchain/src/compiler/visitors/resolver.cc

@@ -234,7 +234,10 @@ struct Visitor : public visitor::PostOrder<void, Visitor> {
             field_types.emplace_back(declaration::Field(f.id(), f.expression().type(), std::nullopt, f.id().meta()));
         }
 
-        auto ntype = type::Struct(type::Struct::AnonymousStruct{}, std::move(field_types), u.meta());
+        Type ntype = type::Struct(type::Struct::AnonymousStruct{}, std::move(field_types), u.meta());
+        if ( auto id = u.type().typeID() )
+            ntype.setTypeID(*id);
+
         logChange(p.node, ntype);
         p.node.as<ctor::Struct>().setType(ntype);
         modified = true;

tests/Baseline/spicy.types.unit.struct-ctor-init-2/output

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+[error] <...>/struct-ctor-init-2.spicy:12:11: type cannot be used as key type for maps (because it is not sortable)
+[error] spicyc: aborting after errors

tests/spicy/types/unit/struct-ctor-init-2.spicy

@@ -0,0 +1,15 @@
+# @TEST-EXEC-FAIL: spicyc -j %INPUT >output 2>&1
+# @TEST-EXEC: btest-diff output
+#
+# @TEST-DOC: Regression test for #1234.
+
+module test;
+
+type Key = unit {a: uint8;};
+
+# The below will be rejeced because units can't be used a key types, but that's
+# fine, we just want to make sure type resolution doesn't complain.
+global m: map<Key, uint8>;
+m[[$a=1]] = 1;
+
+print m;