bytecodealliance · alexcrichton · Apr 27, 2026 · Apr 27, 2026
@@ -2793,16 +2793,18 @@ impl ComponentState {
 
         // Validate `realloc`
         if let Some(realloc_idx) = realloc {
-            let addr_type = match memory {
-                // If a memory was specified, `realloc` must match its address type.
-                Some(memory_idx) => match self.memory_at(memory_idx, offset)?.memory64 {
-                    true => ValType::I64,
-                    false => ValType::I32,
-                },
-                // Backwards compatibility: Assume `i32` memory if none was specified.
-                // FIXME(#2503): The spec requires `memory` if `realloc` is specified, but this
-                // may break existing code.
-                None => ValType::I32,
+            let mty = match memory {
+                Some(i) => self.memory_at(i, offset)?,
+                None => {
+                    return Err(BinaryReaderError::new(
+                        "canonical option `realloc` requires `memory` to also be specified",
+                        offset,
+                    ));
+                }
+            };
+            let addr_type = match mty.memory64 {
+                true => ValType::I64,
+                false => ValType::I32,
             };
             let ty_id = self.core_function_at(realloc_idx, offset)?;
             let func_ty = types[ty_id].unwrap_func();

@@ -80,9 +80,10 @@
   (component
     (core module $m
       (func (export "r") (param i32 i32 i32 i32) (result i32) unreachable)
+      (memory (export "m") 0)
     )
     (core instance $m (instantiate $m))
-    (core func $task-return (canon task.return (result u32) (realloc (func $m "r"))))
+    (core func $task-return (canon task.return (result u32) (realloc (func $m "r")) (memory $m "m")))
   )
   "cannot specify `realloc` option on `task.return`")
 

@@ -0,0 +1,73 @@
+;; RUN: wast --assert default --snapshot tests/snapshots % -f custom-page-sizes
+
+(component
+  (core module $m
+    (func (export "r") (param i32 i32 i32 i32) (result i32) unreachable)
+    (memory (export "m") 0)
+
+    (func (export "f"))
+  )
+  (core instance $i (instantiate $m))
+
+  (func (canon lift (core func $i "f")))
+  (func (canon lift (core func $i "f") (memory $i "m")))
+  (func (canon lift (core func $i "f") (memory $i "m") (realloc (func $i "r"))))
+  (func (canon lift (core func $i "f") (realloc (func $i "r")) (memory $i "m")))
+)
+
+;; `realloc` requires `memory`
+(assert_invalid
+  (component
+    (core module $m
+      (func (export "r") (param i32 i32 i32 i32) (result i32) unreachable)
+      (func (export "f"))
+    )
+    (core instance $i (instantiate $m))
+    (func (canon lift (core func $i "f") (realloc (func $i "r"))))
+  )
+  "canonical option `realloc` requires `memory` to also be specified")
+
+;; even if `realloc` isn't needed, it's still validated
+(assert_invalid
+  (component
+    (core module $m
+      (func (export "r"))
+      (memory (export "m") 0)
+      (func (export "f"))
+    )
+    (core instance $i (instantiate $m))
+    (func (canon lift (core func $i "f") (realloc (func $i "r")) (memory $i "m")))
+  )
+  "canonical option `realloc` uses a core function with an incorrect signature")
+
+;; even if `memory` isn't needed, it's still validated
+(assert_invalid
+  (component
+    (core module $m
+      (memory (export "m") 0 (pagesize 1))
+      (func (export "f"))
+    )
+    (core instance $i (instantiate $m))
+    (func (canon lift (core func $i "f") (memory $i "m")))
+  )
+  "mismatch in page size for memories")
+(assert_invalid
+  (component
+    (core module $m
+      (memory (export "m") 0 1 shared)
+      (func (export "f"))
+    )
+    (core instance $i (instantiate $m))
+    (func (canon lift (core func $i "f") (memory $i "m")))
+  )
+  "mismatch in the shared flag for memories")
+(assert_invalid
+  (component
+    (core module $m
+      (memory (export "m") i64 0)
+      (func (export "f"))
+    )
+    (core instance $i (instantiate $m))
+    (func (canon lift (core func $i "f") (memory $i "m")))
+  )
+  "64-bit memories require the `cm64` feature to be enabled")
@@ -70,237 +70,237 @@
     },
     {
       "type": "module",
-      "line": 89,
+      "line": 90,
       "filename": "task-builtins.10.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 101,
+      "line": 102,
       "filename": "task-builtins.11.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 110,
+      "line": 111,
       "filename": "task-builtins.12.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 118,
+      "line": 119,
       "filename": "task-builtins.13.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.new` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 127,
+      "line": 128,
       "filename": "task-builtins.14.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 139,
+      "line": 140,
       "filename": "task-builtins.15.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.wait` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 151,
+      "line": 152,
       "filename": "task-builtins.16.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 162,
+      "line": 163,
       "filename": "task-builtins.17.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 171,
+      "line": 172,
       "filename": "task-builtins.18.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 183,
+      "line": 184,
       "filename": "task-builtins.19.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.poll` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 196,
+      "line": 197,
       "filename": "task-builtins.20.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 204,
+      "line": 205,
       "filename": "task-builtins.21.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.drop` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 213,
+      "line": 214,
       "filename": "task-builtins.22.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 221,
+      "line": 222,
       "filename": "task-builtins.23.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable.join` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 230,
+      "line": 231,
       "filename": "task-builtins.24.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 240,
+      "line": 241,
       "filename": "task-builtins.25.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `subtask.drop` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 251,
+      "line": 252,
       "filename": "task-builtins.26.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 261,
+      "line": 262,
       "filename": "task-builtins.27.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `subtask.cancel` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 272,
+      "line": 273,
       "filename": "task-builtins.28.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 289,
+      "line": 290,
       "filename": "task-builtins.29.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 297,
+      "line": 298,
       "filename": "task-builtins.30.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 307,
+      "line": 308,
       "filename": "task-builtins.31.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `thread.yield` of module instantiation argument ``"
     },
     {
       "type": "assert_invalid",
-      "line": 318,
+      "line": 319,
       "filename": "task-builtins.32.wasm",
       "module_type": "binary",
       "text": "found:    (func (result i32))"
     },
     {
       "type": "assert_invalid",
-      "line": 325,
+      "line": 326,
       "filename": "task-builtins.33.wasm",
       "module_type": "binary",
       "text": "found:    (func (param i32))"
     },
     {
       "type": "assert_invalid",
-      "line": 332,
+      "line": 333,
       "filename": "task-builtins.34.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 1"
     },
     {
       "type": "assert_invalid",
-      "line": 336,
+      "line": 337,
       "filename": "task-builtins.35.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 1"
     },
     {
       "type": "assert_invalid",
-      "line": 340,
+      "line": 341,
       "filename": "task-builtins.36.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 100"
     },
     {
       "type": "assert_invalid",
-      "line": 344,
+      "line": 345,
       "filename": "task-builtins.37.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 100"
     },
     {
       "type": "assert_invalid",
-      "line": 350,
+      "line": 351,
       "filename": "task-builtins.38.wasm",
       "module_type": "binary",
       "text": "64-bit `context.get` requires the component model 64-bit feature"
     },
     {
       "type": "assert_invalid",
-      "line": 354,
+      "line": 355,
       "filename": "task-builtins.39.wasm",
       "module_type": "binary",
       "text": "64-bit `context.set` requires the component model 64-bit feature"
     },
     {
       "type": "assert_invalid",
-      "line": 359,
+      "line": 360,
       "filename": "task-builtins.40.wasm",
       "module_type": "binary",
       "text": "64-bit `context.get` requires the component model 64-bit feature"
     },
     {
       "type": "assert_invalid",
-      "line": 366,
+      "line": 367,
       "filename": "task-builtins.41.wasm",
       "module_type": "binary",
       "text": "64-bit `context.set` requires the component model 64-bit feature"
     },
     {
       "type": "assert_invalid",
-      "line": 375,
+      "line": 376,
       "filename": "task-builtins.42.wasm",
       "module_type": "binary",
       "text": "`context.get` only supports `i32` or `i64`"
     },
     {
       "type": "assert_invalid",
-      "line": 379,
+      "line": 380,
       "filename": "task-builtins.43.wasm",
       "module_type": "binary",
       "text": "`context.set` only supports `i32` or `i64`"
     },
     {
       "type": "module",
-      "line": 385,
+      "line": 386,
       "filename": "task-builtins.44.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 445,
+      "line": 446,
       "filename": "task-builtins.45.wasm",
       "module_type": "binary"
     }