test: validate compiler against official WebAssembly core suite

Cargo.toml

@@ -24,6 +24,7 @@ insta = "1.48.0"
 predicates = "3.1.4"
 rstest = "0.26.1"
 tempfile = "3.27.0"
+wast = { version = "258.0.0", default-features = false, features = ["wasm-module"] }
 
 [lints.rust]
 unsafe_code = "forbid"

tests/fixtures/wasm-spec/core/README.md

@@ -0,0 +1,24 @@
+# Official WebAssembly core-suite fixture
+
+`i32-arithmetic.wast` is a bounded, checked-in slice of the official
+WebAssembly core test suite. It is copied from
+[`test/core/i32.wast`](https://github.com/WebAssembly/spec/blob/fc209c5ed8afc4dfeb9252024d217da3376c7a6f/test/core/i32.wast)
+at source revision `fc209c5ed8afc4dfeb9252024d217da3376c7a6f`.
+
+The slice covers signed i32 add, subtract, multiply, and divide, including
+wraparound values and the official divide-by-zero and signed-overflow trap
+assertions. It is intentionally not presented as the whole specification
+suite: the current compiler can only execute the subset represented by this
+fixture through its existing decode, translation, and pinned Luau runtime path.
+
+`tests/wasm_spec.rs` parses this fixture with the `wast` parser, encodes each
+module, sends it through `decode_module` and `translate_module`, and executes
+the generated Luau with the pinned official Luau binary. The harness reports
+passed, failed, and skipped-by-scope assertions separately. Return assertions
+for unsupported shapes are skipped by scope; a trap assertion that cannot be
+compiled or executed is a failure, never a pass.
+
+At the current compiler revision this slice reports 17 passed and 4 failed:
+the four failures are the deliberately exercised `div_s` trap assertions.
+That red result is the regression signal for missing trap semantics, not a
+reason to widen the fixture or count unsupported behavior as success.

tests/fixtures/wasm-spec/core/i32-arithmetic.wast

@@ -0,0 +1,36 @@
+;; This fixture is copied from the official WebAssembly core suite's i32.wast.
+;; Keep the source revision and selected assertions documented alongside it.
+
+(module
+  (func (export "add") (param $x i32) (param $y i32) (result i32) (i32.add (local.get $x) (local.get $y)))
+  (func (export "sub") (param $x i32) (param $y i32) (result i32) (i32.sub (local.get $x) (local.get $y)))
+  (func (export "mul") (param $x i32) (param $y i32) (result i32) (i32.mul (local.get $x) (local.get $y)))
+  (func (export "div_s") (param $x i32) (param $y i32) (result i32) (i32.div_s (local.get $x) (local.get $y)))
+)
+
+(assert_return (invoke "add" (i32.const 1) (i32.const 1)) (i32.const 2))
+(assert_return (invoke "add" (i32.const -1) (i32.const 1)) (i32.const 0))
+(assert_return (invoke "add" (i32.const 0x7fffffff) (i32.const 1)) (i32.const 0x80000000))
+(assert_return (invoke "add" (i32.const 0x80000000) (i32.const -1)) (i32.const 0x7fffffff))
+
+(assert_return (invoke "sub" (i32.const 1) (i32.const 1)) (i32.const 0))
+(assert_return (invoke "sub" (i32.const 0x7fffffff) (i32.const -1)) (i32.const 0x80000000))
+(assert_return (invoke "sub" (i32.const 0x80000000) (i32.const 1)) (i32.const 0x7fffffff))
+(assert_return (invoke "sub" (i32.const 0x80000000) (i32.const 0x80000000)) (i32.const 0))
+
+(assert_return (invoke "mul" (i32.const 1) (i32.const 1)) (i32.const 1))
+(assert_return (invoke "mul" (i32.const -1) (i32.const -1)) (i32.const 1))
+(assert_return (invoke "mul" (i32.const 0x10000000) (i32.const 4096)) (i32.const 0))
+(assert_return (invoke "mul" (i32.const 0x80000000) (i32.const -1)) (i32.const 0x80000000))
+(assert_return (invoke "mul" (i32.const 0x7fffffff) (i32.const -1)) (i32.const 0x80000001))
+(assert_return (invoke "mul" (i32.const 0x01234567) (i32.const 0x76543210)) (i32.const 0x358e7470))
+
+;; These trap assertions must fail until the generated helper models the
+;; specification's divide-by-zero and signed-overflow traps.
+(assert_trap (invoke "div_s" (i32.const 1) (i32.const 0)) "integer divide by zero")
+(assert_trap (invoke "div_s" (i32.const 0) (i32.const 0)) "integer divide by zero")
+(assert_trap (invoke "div_s" (i32.const 0x80000000) (i32.const -1)) "integer overflow")
+(assert_trap (invoke "div_s" (i32.const 0x80000000) (i32.const 0)) "integer divide by zero")
+(assert_return (invoke "div_s" (i32.const 1) (i32.const 1)) (i32.const 1))
+(assert_return (invoke "div_s" (i32.const -5) (i32.const 2)) (i32.const -2))
+(assert_return (invoke "div_s" (i32.const 5) (i32.const -2)) (i32.const -2))