From 386f011e386c9eaf1e92c025fa1fad2187793b4e Mon Sep 17 00:00:00 2001
From: Michael Weigelt <michael.weigelt@dfinity.org>
Date: Thu, 23 Apr 2026 13:09:05 +0000
Subject: [PATCH 1/4] realloc

---
 .../src/readers/component/canonicals.rs       |  3 +-
 crates/wasmparser/src/validator/component.rs  | 13 +++--
 .../cli/component-model/memory64/realloc.wast | 50 +++++++++++++++++++
 .../memory64/realloc.wast.json                | 39 +++++++++++++++
 .../memory64/realloc.wast/0.print             | 22 ++++++++
 .../memory64/realloc.wast/13.print            | 26 ++++++++++
 .../memory64/realloc.wast/2.print             | 26 ++++++++++
 .../memory64/realloc.wast/3.print             | 26 ++++++++++
 8 files changed, 201 insertions(+), 4 deletions(-)
 create mode 100644 tests/cli/component-model/memory64/realloc.wast
 create mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast.json
 create mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/0.print
 create mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
 create mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
 create mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/3.print

diff --git a/crates/wasmparser/src/readers/component/canonicals.rs b/crates/wasmparser/src/readers/component/canonicals.rs
index 26df1257cd..76ac7b86bc 100644
--- a/crates/wasmparser/src/readers/component/canonicals.rs
+++ b/crates/wasmparser/src/readers/component/canonicals.rs
@@ -18,7 +18,8 @@ pub enum CanonicalOption {
     /// The realloc function to use if the lifting or lowering of a function requires memory
     /// allocation.
     ///
-    /// The value is an index to a core function of type `(func (param i32 i32 i32 i32) (result i32))`.
+    /// The value is an index to a core function of type `(func (param $T $T $T $T) (result $T))` where
+    /// `$T` is the index type of the memory, i.e., either `i32` or `i64`.
     Realloc(u32),
     /// The post-return function to use if the lifting of a function requires
     /// cleanup after the function returns.
diff --git a/crates/wasmparser/src/validator/component.rs b/crates/wasmparser/src/validator/component.rs
index f323315630..95efea2f2c 100644
--- a/crates/wasmparser/src/validator/component.rs
+++ b/crates/wasmparser/src/validator/component.rs
@@ -2635,11 +2635,18 @@ impl ComponentState {
                 CanonicalOption::Realloc(idx) => {
                     realloc = match realloc {
                         None => {
+                            let memory_idx = memory.ok_or(BinaryReaderError::new(
+                                "canonical option `realloc` requires the `memory` option",
+                                offset,
+                            ))?;
+                            let addr_type = match self.memory_at(memory_idx, offset)?.memory64 {
+                                true => ValType::I64,
+                                false => ValType::I32,
+                            };
                             let ty_id = self.core_function_at(*idx, offset)?;
                             let func_ty = types[ty_id].unwrap_func();
-                            if func_ty.params()
-                                != [ValType::I32, ValType::I32, ValType::I32, ValType::I32]
-                                || func_ty.results() != [ValType::I32]
+                            if func_ty.params() != [addr_type, addr_type, addr_type, addr_type]
+                                || func_ty.results() != [addr_type]
                             {
                                 return Err(BinaryReaderError::new(
                                     "canonical option `realloc` uses a core function with an incorrect signature",
diff --git a/tests/cli/component-model/memory64/realloc.wast b/tests/cli/component-model/memory64/realloc.wast
new file mode 100644
index 0000000000..12fc13d71c
--- /dev/null
+++ b/tests/cli/component-model/memory64/realloc.wast
@@ -0,0 +1,50 @@
+;; RUN: wast --assert default --snapshot tests/snapshots -f cm64 %
+
+(component
+  (core module $m
+    (memory (export "m") i64 1)
+    (func (export "f") (result i32) unreachable)
+    (func (export "realloc") (param i64 i64 i64 i64) (result i64) unreachable)
+  )
+  (core instance $i (instantiate $m))
+  (func (result string)
+    (canon lift (core func $i "f")
+      (memory $i "m")
+      (realloc (func $i "realloc"))
+    )
+  )
+)
+
+(assert_invalid
+  (component
+    (core module $m
+      (memory (export "m") i64 1)
+      (func (export "f") (param i32 i32))
+      (func (export "realloc") (param i32 i32 i32 i32) (result i32) unreachable)
+    )
+    (core instance $i (instantiate $m))
+    (func (param "p1" (list u8))
+      (canon lift (core func $i "f")
+        (memory $i "m")
+        (realloc (func $i "realloc"))
+      )
+    )
+  )
+  "canonical option `realloc` uses a core function with an incorrect signature")
+
+(assert_invalid
+  (component
+    (core module $m
+      (memory (export "m") i32 1)
+      (func (export "f") (param i32 i32))
+      (func (export "realloc") (param i64 i64 i64 i64) (result i64) unreachable)
+    )
+    (core instance $i (instantiate $m))
+    (func (param "p1" (list u8))
+      (canon lift (core func $i "f")
+        (memory $i "m")
+        (realloc (func $i "realloc"))
+      )
+    )
+  )
+  "canonical option `realloc` uses a core function with an incorrect signature")
\ No newline at end of file
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast.json b/tests/snapshots/cli/component-model/memory64/realloc.wast.json
new file mode 100644
index 0000000000..62a1e15fba
--- /dev/null
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast.json
@@ -0,0 +1,39 @@
+{
+  "source_filename": "tests/cli/component-model/memory64/realloc.wast",
+  "commands": [
+    {
+      "type": "module",
+      "line": 3,
+      "filename": "realloc.0.wasm",
+      "module_type": "binary"
+    },
+    {
+      "type": "assert_invalid",
+      "line": 19,
+      "filename": "realloc.1.wasm",
+      "module_type": "binary",
+      "text": "canonical option `realloc` uses a core function with an incorrect signature"
+    },
+    {
+      "type": "assert_invalid",
+      "line": 36,
+      "filename": "realloc.2.wasm",
+      "module_type": "binary",
+      "text": "canonical option `realloc` uses a core function with an incorrect signature"
+    },
+    {
+      "type": "assert_invalid",
+      "line": 53,
+      "filename": "realloc.3.wasm",
+      "module_type": "binary",
+      "text": "lowered parameter types `[]` do not match parameter types `[I32]`"
+    },
+    {
+      "type": "assert_invalid",
+      "line": 61,
+      "filename": "realloc.4.wasm",
+      "module_type": "binary",
+      "text": "lowered result types `[]` do not match result types `[I32]`"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/0.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/0.print
new file mode 100644
index 0000000000..6b1f904c64
--- /dev/null
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast/0.print
@@ -0,0 +1,22 @@
+(component
+  (core module $m (;0;)
+    (type (;0;) (func (result i32)))
+    (type (;1;) (func (param i64 i64 i64 i64) (result i64)))
+    (memory (;0;) i64 1)
+    (export "m" (memory 0))
+    (export "f" (func 0))
+    (export "realloc" (func 1))
+    (func (;0;) (type 0) (result i32)
+      unreachable
+    )
+    (func (;1;) (type 1) (param i64 i64 i64 i64) (result i64)
+      unreachable
+    )
+  )
+  (core instance $i (;0;) (instantiate $m))
+  (type (;0;) (func (result string)))
+  (alias core export $i "f" (core func (;0;)))
+  (alias core export $i "m" (core memory (;0;)))
+  (alias core export $i "realloc" (core func (;1;)))
+  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1)))
+)
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
new file mode 100644
index 0000000000..33ae157f20
--- /dev/null
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
@@ -0,0 +1,26 @@
+(component
+  (core module $m (;0;)
+    (type (;0;) (func (result i32)))
+    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
+    (type (;2;) (func (param i32)))
+    (memory (;0;) 1)
+    (export "m" (memory 0))
+    (export "f" (func 0))
+    (export "r" (func 1))
+    (export "p" (func 2))
+    (func (;0;) (type 0) (result i32)
+      unreachable
+    )
+    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
+      unreachable
+    )
+    (func (;2;) (type 2) (param i32))
+  )
+  (core instance $i (;0;) (instantiate $m))
+  (type (;0;) (func (result string)))
+  (alias core export $i "f" (core func (;0;)))
+  (alias core export $i "m" (core memory (;0;)))
+  (alias core export $i "r" (core func (;1;)))
+  (alias core export $i "p" (core func (;2;)))
+  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
+)
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
new file mode 100644
index 0000000000..33ae157f20
--- /dev/null
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
@@ -0,0 +1,26 @@
+(component
+  (core module $m (;0;)
+    (type (;0;) (func (result i32)))
+    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
+    (type (;2;) (func (param i32)))
+    (memory (;0;) 1)
+    (export "m" (memory 0))
+    (export "f" (func 0))
+    (export "r" (func 1))
+    (export "p" (func 2))
+    (func (;0;) (type 0) (result i32)
+      unreachable
+    )
+    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
+      unreachable
+    )
+    (func (;2;) (type 2) (param i32))
+  )
+  (core instance $i (;0;) (instantiate $m))
+  (type (;0;) (func (result string)))
+  (alias core export $i "f" (core func (;0;)))
+  (alias core export $i "m" (core memory (;0;)))
+  (alias core export $i "r" (core func (;1;)))
+  (alias core export $i "p" (core func (;2;)))
+  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
+)
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print
new file mode 100644
index 0000000000..33ae157f20
--- /dev/null
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print
@@ -0,0 +1,26 @@
+(component
+  (core module $m (;0;)
+    (type (;0;) (func (result i32)))
+    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
+    (type (;2;) (func (param i32)))
+    (memory (;0;) 1)
+    (export "m" (memory 0))
+    (export "f" (func 0))
+    (export "r" (func 1))
+    (export "p" (func 2))
+    (func (;0;) (type 0) (result i32)
+      unreachable
+    )
+    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
+      unreachable
+    )
+    (func (;2;) (type 2) (param i32))
+  )
+  (core instance $i (;0;) (instantiate $m))
+  (type (;0;) (func (result string)))
+  (alias core export $i "f" (core func (;0;)))
+  (alias core export $i "m" (core memory (;0;)))
+  (alias core export $i "r" (core func (;1;)))
+  (alias core export $i "p" (core func (;2;)))
+  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
+)

From 421ab314d45c1ef81165276524f0ad1da0042675 Mon Sep 17 00:00:00 2001
From: Michael Weigelt <michael.weigelt@dfinity.org>
Date: Thu, 23 Apr 2026 13:23:18 +0000
Subject: [PATCH 2/4] fix task.return

---
 .../component-model/async/task-builtins.wast  |  3 +-
 .../async/task-builtins.wast.json             | 68 +++++++++----------
 2 files changed, 36 insertions(+), 35 deletions(-)

diff --git a/tests/cli/component-model/async/task-builtins.wast b/tests/cli/component-model/async/task-builtins.wast
index 7cc328897e..060ee7a78d 100644
--- a/tests/cli/component-model/async/task-builtins.wast
+++ b/tests/cli/component-model/async/task-builtins.wast
@@ -79,10 +79,11 @@
 (assert_invalid
   (component
     (core module $m
+      (memory (export "m") i32 1)
       (func (export "r") (param i32 i32 i32 i32) (result i32) unreachable)
     )
     (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) (memory $m "m") (realloc (func $m "r"))))
   )
   "cannot specify `realloc` option on `task.return`")
 
diff --git a/tests/snapshots/cli/component-model/async/task-builtins.wast.json b/tests/snapshots/cli/component-model/async/task-builtins.wast.json
index 195e931af7..8d9b3d4e17 100644
--- a/tests/snapshots/cli/component-model/async/task-builtins.wast.json
+++ b/tests/snapshots/cli/component-model/async/task-builtins.wast.json
@@ -70,223 +70,223 @@
     },
     {
       "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_malformed",
-      "line": 348,
+      "line": 349,
       "filename": "task-builtins.38.wat",
       "module_type": "text",
       "text": "expected keyword `i32`"
     },
     {
       "type": "assert_malformed",
-      "line": 352,
+      "line": 353,
       "filename": "task-builtins.39.wat",
       "module_type": "text",
       "text": "expected keyword `i32`"
     },
     {
       "type": "assert_malformed",
-      "line": 357,
+      "line": 358,
       "filename": "task-builtins.40.wasm",
       "module_type": "binary",
       "text": "invalid leading byte (0x7e) for context.get"
     },
     {
       "type": "assert_malformed",
-      "line": 364,
+      "line": 365,
       "filename": "task-builtins.41.wasm",
       "module_type": "binary",
       "text": "invalid leading byte (0x7e) for context.set"
     },
     {
       "type": "module",
-      "line": 373,
+      "line": 374,
       "filename": "task-builtins.42.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 433,
+      "line": 434,
       "filename": "task-builtins.43.wasm",
       "module_type": "binary"
     }

From 9c2069836138d8ce66bf9680495e3e3d7a645ede Mon Sep 17 00:00:00 2001
From: Michael Weigelt <michael.weigelt@dfinity.org>
Date: Thu, 23 Apr 2026 13:30:24 +0000
Subject: [PATCH 3/4] files

---
 .../memory64/realloc.wast.json                | 14 ----------
 .../memory64/realloc.wast/13.print            | 26 -------------------
 .../memory64/realloc.wast/2.print             | 26 -------------------
 .../memory64/realloc.wast/3.print             | 26 -------------------
 4 files changed, 92 deletions(-)
 delete mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
 delete mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
 delete mode 100644 tests/snapshots/cli/component-model/memory64/realloc.wast/3.print

diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast.json b/tests/snapshots/cli/component-model/memory64/realloc.wast.json
index 62a1e15fba..fe0b7dd7d9 100644
--- a/tests/snapshots/cli/component-model/memory64/realloc.wast.json
+++ b/tests/snapshots/cli/component-model/memory64/realloc.wast.json
@@ -20,20 +20,6 @@
       "filename": "realloc.2.wasm",
       "module_type": "binary",
       "text": "canonical option `realloc` uses a core function with an incorrect signature"
-    },
-    {
-      "type": "assert_invalid",
-      "line": 53,
-      "filename": "realloc.3.wasm",
-      "module_type": "binary",
-      "text": "lowered parameter types `[]` do not match parameter types `[I32]`"
-    },
-    {
-      "type": "assert_invalid",
-      "line": 61,
-      "filename": "realloc.4.wasm",
-      "module_type": "binary",
-      "text": "lowered result types `[]` do not match result types `[I32]`"
     }
   ]
 }
\ No newline at end of file
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
deleted file mode 100644
index 33ae157f20..0000000000
--- a/tests/snapshots/cli/component-model/memory64/realloc.wast/13.print
+++ /dev/null
@@ -1,26 +0,0 @@
-(component
-  (core module $m (;0;)
-    (type (;0;) (func (result i32)))
-    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
-    (type (;2;) (func (param i32)))
-    (memory (;0;) 1)
-    (export "m" (memory 0))
-    (export "f" (func 0))
-    (export "r" (func 1))
-    (export "p" (func 2))
-    (func (;0;) (type 0) (result i32)
-      unreachable
-    )
-    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
-      unreachable
-    )
-    (func (;2;) (type 2) (param i32))
-  )
-  (core instance $i (;0;) (instantiate $m))
-  (type (;0;) (func (result string)))
-  (alias core export $i "f" (core func (;0;)))
-  (alias core export $i "m" (core memory (;0;)))
-  (alias core export $i "r" (core func (;1;)))
-  (alias core export $i "p" (core func (;2;)))
-  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
-)
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
deleted file mode 100644
index 33ae157f20..0000000000
--- a/tests/snapshots/cli/component-model/memory64/realloc.wast/2.print
+++ /dev/null
@@ -1,26 +0,0 @@
-(component
-  (core module $m (;0;)
-    (type (;0;) (func (result i32)))
-    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
-    (type (;2;) (func (param i32)))
-    (memory (;0;) 1)
-    (export "m" (memory 0))
-    (export "f" (func 0))
-    (export "r" (func 1))
-    (export "p" (func 2))
-    (func (;0;) (type 0) (result i32)
-      unreachable
-    )
-    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
-      unreachable
-    )
-    (func (;2;) (type 2) (param i32))
-  )
-  (core instance $i (;0;) (instantiate $m))
-  (type (;0;) (func (result string)))
-  (alias core export $i "f" (core func (;0;)))
-  (alias core export $i "m" (core memory (;0;)))
-  (alias core export $i "r" (core func (;1;)))
-  (alias core export $i "p" (core func (;2;)))
-  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
-)
diff --git a/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print b/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print
deleted file mode 100644
index 33ae157f20..0000000000
--- a/tests/snapshots/cli/component-model/memory64/realloc.wast/3.print
+++ /dev/null
@@ -1,26 +0,0 @@
-(component
-  (core module $m (;0;)
-    (type (;0;) (func (result i32)))
-    (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
-    (type (;2;) (func (param i32)))
-    (memory (;0;) 1)
-    (export "m" (memory 0))
-    (export "f" (func 0))
-    (export "r" (func 1))
-    (export "p" (func 2))
-    (func (;0;) (type 0) (result i32)
-      unreachable
-    )
-    (func (;1;) (type 1) (param i32 i32 i32 i32) (result i32)
-      unreachable
-    )
-    (func (;2;) (type 2) (param i32))
-  )
-  (core instance $i (;0;) (instantiate $m))
-  (type (;0;) (func (result string)))
-  (alias core export $i "f" (core func (;0;)))
-  (alias core export $i "m" (core memory (;0;)))
-  (alias core export $i "r" (core func (;1;)))
-  (alias core export $i "p" (core func (;2;)))
-  (func (;0;) (type 0) (canon lift (core func 0) (memory 0) (realloc 1) (post-return 2)))
-)

From 168015381943d7fffb0301ba3925c58b11fdf6ee Mon Sep 17 00:00:00 2001
From: Michael Weigelt <michael.weigelt@dfinity.org>
Date: Fri, 24 Apr 2026 09:25:43 +0000
Subject: [PATCH 4/4] address comments

---
 crates/wasmparser/src/validator/component.rs  | 42 +++++++-----
 .../component-model/async/task-builtins.wast  |  3 +-
 .../async/task-builtins.wast.json             | 68 +++++++++----------
 3 files changed, 59 insertions(+), 54 deletions(-)

diff --git a/crates/wasmparser/src/validator/component.rs b/crates/wasmparser/src/validator/component.rs
index 95efea2f2c..83b1749a48 100644
--- a/crates/wasmparser/src/validator/component.rs
+++ b/crates/wasmparser/src/validator/component.rs
@@ -2635,24 +2635,7 @@ impl ComponentState {
                 CanonicalOption::Realloc(idx) => {
                     realloc = match realloc {
                         None => {
-                            let memory_idx = memory.ok_or(BinaryReaderError::new(
-                                "canonical option `realloc` requires the `memory` option",
-                                offset,
-                            ))?;
-                            let addr_type = match self.memory_at(memory_idx, offset)?.memory64 {
-                                true => ValType::I64,
-                                false => ValType::I32,
-                            };
-                            let ty_id = self.core_function_at(*idx, offset)?;
-                            let func_ty = types[ty_id].unwrap_func();
-                            if func_ty.params() != [addr_type, addr_type, addr_type, addr_type]
-                                || func_ty.results() != [addr_type]
-                            {
-                                return Err(BinaryReaderError::new(
-                                    "canonical option `realloc` uses a core function with an incorrect signature",
-                                    offset,
-                                ));
-                            }
+                            // Validation deferred because it may depend on the memory option.
                             Some(*idx)
                         }
                         Some(_) => {
@@ -2778,6 +2761,29 @@ impl ComponentState {
             bail!(offset, "cannot specify `core-type` without `gc`")
         }
 
+        // 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.
+                None => ValType::I32,
+            };
+            let ty_id = self.core_function_at(realloc_idx, offset)?;
+            let func_ty = types[ty_id].unwrap_func();
+            if func_ty.params() != [addr_type, addr_type, addr_type, addr_type]
+                || func_ty.results() != [addr_type]
+            {
+                return Err(BinaryReaderError::new(
+                    "canonical option `realloc` uses a core function with an incorrect signature",
+                    offset,
+                ));
+            }
+        }
+
         Ok(CanonicalOptions {
             string_encoding,
             memory,
diff --git a/tests/cli/component-model/async/task-builtins.wast b/tests/cli/component-model/async/task-builtins.wast
index 060ee7a78d..7cc328897e 100644
--- a/tests/cli/component-model/async/task-builtins.wast
+++ b/tests/cli/component-model/async/task-builtins.wast
@@ -79,11 +79,10 @@
 (assert_invalid
   (component
     (core module $m
-      (memory (export "m") i32 1)
       (func (export "r") (param i32 i32 i32 i32) (result i32) unreachable)
     )
     (core instance $m (instantiate $m))
-    (core func $task-return (canon task.return (result u32) (memory $m "m") (realloc (func $m "r"))))
+    (core func $task-return (canon task.return (result u32) (realloc (func $m "r"))))
   )
   "cannot specify `realloc` option on `task.return`")
 
diff --git a/tests/snapshots/cli/component-model/async/task-builtins.wast.json b/tests/snapshots/cli/component-model/async/task-builtins.wast.json
index 8d9b3d4e17..195e931af7 100644
--- a/tests/snapshots/cli/component-model/async/task-builtins.wast.json
+++ b/tests/snapshots/cli/component-model/async/task-builtins.wast.json
@@ -70,223 +70,223 @@
     },
     {
       "type": "module",
-      "line": 90,
+      "line": 89,
       "filename": "task-builtins.10.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 102,
+      "line": 101,
       "filename": "task-builtins.11.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 111,
+      "line": 110,
       "filename": "task-builtins.12.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 119,
+      "line": 118,
       "filename": "task-builtins.13.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.new` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 128,
+      "line": 127,
       "filename": "task-builtins.14.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 140,
+      "line": 139,
       "filename": "task-builtins.15.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.wait` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 152,
+      "line": 151,
       "filename": "task-builtins.16.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 163,
+      "line": 162,
       "filename": "task-builtins.17.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 172,
+      "line": 171,
       "filename": "task-builtins.18.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 184,
+      "line": 183,
       "filename": "task-builtins.19.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.poll` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 197,
+      "line": 196,
       "filename": "task-builtins.20.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 205,
+      "line": 204,
       "filename": "task-builtins.21.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable-set.drop` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 214,
+      "line": 213,
       "filename": "task-builtins.22.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 222,
+      "line": 221,
       "filename": "task-builtins.23.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `waitable.join` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 231,
+      "line": 230,
       "filename": "task-builtins.24.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 241,
+      "line": 240,
       "filename": "task-builtins.25.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `subtask.drop` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 252,
+      "line": 251,
       "filename": "task-builtins.26.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 262,
+      "line": 261,
       "filename": "task-builtins.27.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `subtask.cancel` of module instantiation argument ``"
     },
     {
       "type": "module",
-      "line": 273,
+      "line": 272,
       "filename": "task-builtins.28.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 290,
+      "line": 289,
       "filename": "task-builtins.29.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 298,
+      "line": 297,
       "filename": "task-builtins.30.wasm",
       "module_type": "binary"
     },
     {
       "type": "assert_invalid",
-      "line": 308,
+      "line": 307,
       "filename": "task-builtins.31.wasm",
       "module_type": "binary",
       "text": "type mismatch for export `thread.yield` of module instantiation argument ``"
     },
     {
       "type": "assert_invalid",
-      "line": 319,
+      "line": 318,
       "filename": "task-builtins.32.wasm",
       "module_type": "binary",
       "text": "found:    (func (result i32))"
     },
     {
       "type": "assert_invalid",
-      "line": 326,
+      "line": 325,
       "filename": "task-builtins.33.wasm",
       "module_type": "binary",
       "text": "found:    (func (param i32))"
     },
     {
       "type": "assert_invalid",
-      "line": 333,
+      "line": 332,
       "filename": "task-builtins.34.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 1"
     },
     {
       "type": "assert_invalid",
-      "line": 337,
+      "line": 336,
       "filename": "task-builtins.35.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 1"
     },
     {
       "type": "assert_invalid",
-      "line": 341,
+      "line": 340,
       "filename": "task-builtins.36.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 100"
     },
     {
       "type": "assert_invalid",
-      "line": 345,
+      "line": 344,
       "filename": "task-builtins.37.wasm",
       "module_type": "binary",
       "text": "immediate must be zero: 100"
     },
     {
       "type": "assert_malformed",
-      "line": 349,
+      "line": 348,
       "filename": "task-builtins.38.wat",
       "module_type": "text",
       "text": "expected keyword `i32`"
     },
     {
       "type": "assert_malformed",
-      "line": 353,
+      "line": 352,
       "filename": "task-builtins.39.wat",
       "module_type": "text",
       "text": "expected keyword `i32`"
     },
     {
       "type": "assert_malformed",
-      "line": 358,
+      "line": 357,
       "filename": "task-builtins.40.wasm",
       "module_type": "binary",
       "text": "invalid leading byte (0x7e) for context.get"
     },
     {
       "type": "assert_malformed",
-      "line": 365,
+      "line": 364,
       "filename": "task-builtins.41.wasm",
       "module_type": "binary",
       "text": "invalid leading byte (0x7e) for context.set"
     },
     {
       "type": "module",
-      "line": 374,
+      "line": 373,
       "filename": "task-builtins.42.wasm",
       "module_type": "binary"
     },
     {
       "type": "module",
-      "line": 434,
+      "line": 433,
       "filename": "task-builtins.43.wasm",
       "module_type": "binary"
     }