Update the consequences of disabling the `gc` crate feature (#9162)

* Update the consequences of disabling the `gc` crate feature

This commit updates what happens when the `gc` Cargo feature is disabled
at compile time when compiling Wasmtime itself. Previously this would
disable the reference-types proposal (and eventually once finished the
gc/function-references proposal). This has the downside, however, of
additionally disabling non-gc-related features that were bundled into
the `reference-types` proposal such as multi-table and the encodings of
table indices as LEBs in `call_indirect` instructions for example.

The change in this commit is to instead toggle the newly-added
`GC_TYPES` feature in `wasmparser`. This feature does not correspond to
upstream wasm proposals and instead only gates types such as `externref`
or `anyref`. The `funcref` and `exnref` types are not gated as they're
not expected to require a full GC.

This means that in Wasmtime the `reference-types` feature is now always
active by default regardless of crate features. If the `gc` crate
feature is disabled then only `externref` values are disallowed.

This additionally flags `GC_TYPES` as unsupported in Winch due to no
support for `externref` yet. This means, though, that Winch can be
considered as supporting the `reference-types` proposal (and things like
multi-table) as expected. Disabling `externref` support switched a few
tests to failing so those exceptions are now listed in `tests/wast.rs`

* Fix aarch64 tests

* Fix older invocations of `check_cfg_bool`

crates/wasmtime/src/config.rs

@@ -1750,16 +1750,16 @@ impl Config {
                     | WasmFeatures::FUNCTION_REFERENCES
                     | WasmFeatures::THREADS
                     | WasmFeatures::RELAXED_SIMD
-                    | WasmFeatures::TAIL_CALL;
+                    | WasmFeatures::TAIL_CALL
+                    | WasmFeatures::GC_TYPES;
                 match self.compiler_target().architecture {
                     target_lexicon::Architecture::Aarch64(_) => {
                         // no support for simd on aarch64
                         unsupported |= WasmFeatures::SIMD;
-                        // technically this is mostly supported in the sense of
-                        // multi-tables work well enough but enough of MVP wasm
-                        // currently panics that this is used here instead to
-                        // disable most spec tests which require reference
-                        // types.
+
+                        // things like multi-table are technically supported on
+                        // winch on aarch64 but this helps gate most spec tests
+                        // by default which otherwise currently cause panics.
                         unsupported |= WasmFeatures::REFERENCE_TYPES;
                     }
 
@@ -1791,7 +1791,6 @@ impl Config {
         // subject to the criteria at
         // https://docs.wasmtime.dev/contributing-implementing-wasm-proposals.html
         features |= WasmFeatures::FLOATS;
-        features |= WasmFeatures::GC_TYPES;
         features |= WasmFeatures::MULTI_VALUE;
         features |= WasmFeatures::BULK_MEMORY;
         features |= WasmFeatures::SIGN_EXTENSION;
@@ -1802,8 +1801,9 @@ impl Config {
         features |= WasmFeatures::RELAXED_SIMD;
         features |= WasmFeatures::TAIL_CALL;
         features |= WasmFeatures::EXTENDED_CONST;
+        features |= WasmFeatures::REFERENCE_TYPES;
         if cfg!(feature = "gc") {
-            features |= WasmFeatures::REFERENCE_TYPES;
+            features |= WasmFeatures::GC_TYPES;
         }
         if cfg!(feature = "threads") {
             features |= WasmFeatures::THREADS;

crates/wasmtime/src/engine/serialization.rs

@@ -484,28 +484,21 @@ impl Metadata<'_> {
         } = self.features;
 
         use wasmparser::WasmFeatures as F;
-        Self::check_cfg_bool(
-            cfg!(feature = "gc"),
-            "gc",
+        Self::check_bool(
             reference_types,
             other.contains(F::REFERENCE_TYPES),
             "WebAssembly reference types support",
         )?;
-        Self::check_cfg_bool(
-            cfg!(feature = "gc"),
-            "gc",
+        Self::check_bool(
             function_references,
             other.contains(F::FUNCTION_REFERENCES),
             "WebAssembly function-references support",
         )?;
-        Self::check_cfg_bool(
-            cfg!(feature = "gc"),
-            "gc",
+        Self::check_bool(
             gc,
             other.contains(F::GC),
             "WebAssembly garbage collection support",
         )?;
-
         Self::check_bool(
             multi_value,
             other.contains(F::MULTI_VALUE),
@@ -572,7 +565,9 @@ impl Metadata<'_> {
             other.contains(F::COMPONENT_MODEL_MULTIPLE_RETURNS),
             "WebAssembly component model support for multiple returns",
         )?;
-        Self::check_bool(
+        Self::check_cfg_bool(
+            cfg!(feature = "gc"),
+            "gc",
             gc_types,
             other.contains(F::GC_TYPES),
             "support for WebAssembly gc types",

tests/wast.rs

@@ -73,9 +73,15 @@ fn should_fail(test: &Path, strategy: Strategy) -> bool {
     if strategy == Strategy::Winch {
         let unsupported = [
             // externref/reference-types related
+            "component-model/modules.wast",
+            "extended-const/elem.wast",
+            "extended-const/global.wast",
             "memory64/threads.wast",
             "misc_testsuite/externref-id-function.wast",
+            "misc_testsuite/externref-segment.wast",
             "misc_testsuite/externref-segments.wast",
+            "misc_testsuite/externref-table-dropped-segment-issue-8281.wast",
+            "misc_testsuite/linking-errors.wast",
             "misc_testsuite/many_table_gets_lead_to_gc.wast",
             "misc_testsuite/mutable_externref_globals.wast",
             "misc_testsuite/no-mixup-stack-maps.wast",
@@ -86,18 +92,18 @@ fn should_fail(test: &Path, strategy: Strategy) -> bool {
             "spec_testsuite/data-invalid.wast",
             "spec_testsuite/elem.wast",
             "spec_testsuite/global.wast",
+            "spec_testsuite/linking.wast",
             "spec_testsuite/ref_func.wast",
             "spec_testsuite/ref_is_null.wast",
             "spec_testsuite/ref_null.wast",
             "spec_testsuite/select.wast",
+            "spec_testsuite/table-sub.wast",
             "spec_testsuite/table_fill.wast",
             "spec_testsuite/table_get.wast",
             "spec_testsuite/table_grow.wast",
             "spec_testsuite/table_set.wast",
             "spec_testsuite/table_size.wast",
             "spec_testsuite/unreached-invalid.wast",
-            "extended-const/elem.wast",
-            "extended-const/global.wast",
             // simd-related failures
             "annotations/simd_lane.wast",
             "memory64/simd.wast",