Components: implement exception-tag translation in core module types. (#12122)

* Components: implement exception-tag translation in core module types.

Fixes #12120.

* Add `exceptions = true` config to wast.

Author: cfallin

crates/environ/src/component/types_builder.rs

@@ -411,7 +411,16 @@ impl ComponentTypesBuilder {
             Table(ty) => EntityType::Table(self.convert_table_type(ty)?),
             Memory(ty) => EntityType::Memory((*ty).into()),
             Global(ty) => EntityType::Global(self.convert_global_type(ty)?),
-            Tag(_) => bail!("exceptions proposal not implemented"),
+            Tag(id) => {
+                let func = self.module_types_builder_mut().intern_type(types, *id)?;
+                let exc = self
+                    .module_types_builder_mut()
+                    .define_exception_type_for_tag(func);
+                EntityType::Tag(crate::types::Tag {
+                    signature: func.into(),
+                    exception: exc.into(),
+                })
+            }
             FuncExact(_) => bail!("custom-descriptors proposal not implemented"),
         })
     }

tests/misc_testsuite/component-model/modules.wast

@@ -1,4 +1,5 @@
 ;;! reference_types = true
+;;! exceptions = true
 
 (component $foo
   (core module (export "a-module"))
@@ -477,3 +478,12 @@
 
   (core instance (instantiate $import_globals (with "" (instance $m))))
 )
+
+(component $tag-module
+  (core module (export "m")
+        (tag (export "t") (param i32))))
+(component
+  (import "tag-module" (instance
+                         (export "m"
+                                 (core module
+                                       (export "t" (tag (param i32))))))))