Add a `--hybrid` type system option (#4460)

Eventually this will enable the isorecursive hybrid type system described in
https://github.com/WebAssembly/gc/pull/243, but for now it just throws a fatal
error if used.

3 files changed, 13 insertions, 0 deletions

diff --git a/src/tools/tool-options.h b/src/tools/tool-options.h
index f45569648..0ed0f27fb 100644
--- a/src/tools/tool-options.h
+++ b/src/tools/tool-options.h
@@ -135,6 +135,15 @@ struct ToolOptions : public Options {
            Options::Arguments::Zero,
            [](Options* o, const std::string& argument) {
              setTypeSystem(TypeSystem::Equirecursive);
+           })
+      .add("--hybrid",
+           "",
+           "Force all GC type definitions to be parsed using the isorecursive "
+           "hybrid type system.",
+           ToolOptionsCategory,
+           Options::Arguments::Zero,
+           [](Options* o, const std::string& argument) {
+             setTypeSystem(TypeSystem::Isorecursive);
            });
   }
 
diff --git a/src/wasm-type.h b/src/wasm-type.h
index a54104cc0..c80e7cd0b 100644
--- a/src/wasm-type.h
+++ b/src/wasm-type.h
@@ -36,6 +36,7 @@ namespace wasm {
 enum class TypeSystem {
   Equirecursive,
   Nominal,
+  Isorecursive,
 };
 
 // This should only ever be called before any Types or HeapTypes have been
diff --git a/src/wasm/wasm-type.cpp b/src/wasm/wasm-type.cpp
index a63c66770..738cd6e29 100644
--- a/src/wasm/wasm-type.cpp
+++ b/src/wasm/wasm-type.cpp
@@ -3197,6 +3197,9 @@ std::vector<HeapType> TypeBuilder::build() {
     case TypeSystem::Nominal:
       canonicalizeNominal(state);
       break;
+    case TypeSystem::Isorecursive:
+      Fatal() << "Isorecursive types not yet implemented";
+      break;
   }
 
 #if TIME_CANONICALIZATION