Stream: git-wasmtime

Topic: wasmtime / issue #12284 wasmtime::module::image_range onl...

Wasmtime GitHub notifications bot (Jan 08 2026 at 15:17):

jeffcharles opened issue #12284:

Test Case

Any Wasm module.

Steps to Reproduce

    let engine = Engine::default();
    let module = Module::from_file(&engine, "testcase.wasm").unwrap();
    let range = module.image_range();
    let offset = unsafe { range.end.offset_from(range.start) };
    println!("Offset is {offset}");

Expected Results

The documentation for the method says:

Returns the range of bytes in memory where this module’s compilation image resides.

The compilation image for a module contains executable code, data, debug information, etc. This is roughly the same as the Module::serialize but not the exact same.

I was expecting the range to contain the bytes that contain all of the compilation image.

Actual Results

The range contains the bytes for the executable code but no longer includes data, debug information, or any other parts of the compilation image.

The source code for the method appears to only retrieve the text section.

Versions and Environment

Wasmtime version or commit: Wasmtime 40.0.0

Operating system: All

Architecture: All

Extra Info

We're using the image_size API in wasmtime-rb to inform the Ruby garbage collector about the size of the memory used for the anonymous mmap when creating a module.

It looks like the change in implementation was introduced here on line 975.

Wasmtime GitHub notifications bot (Jan 08 2026 at 15:17):

jeffcharles added the bug label to Issue #12284.

Wasmtime GitHub notifications bot (Jan 09 2026 at 01:40):

alexcrichton commented on issue #12284:

Thanks for the report and for the bisection! cc @cfallin when you get back would you be willing to take a look at this?

Wasmtime GitHub notifications bot (Jan 09 2026 at 08:27):

cfallin commented on issue #12284:

Yep, just sent a PR -- sorry and thanks for the heads-up!

Wasmtime GitHub notifications bot (Jan 09 2026 at 19:29):

cfallin closed issue #12284:

Test Case

Any Wasm module.

Steps to Reproduce

    let engine = Engine::default();
    let module = Module::from_file(&engine, "testcase.wasm").unwrap();
    let range = module.image_range();
    let offset = unsafe { range.end.offset_from(range.start) };
    println!("Offset is {offset}");

Expected Results

The documentation for the method says:

Returns the range of bytes in memory where this module’s compilation image resides.

The compilation image for a module contains executable code, data, debug information, etc. This is roughly the same as the Module::serialize but not the exact same.

I was expecting the range to contain the bytes that contain all of the compilation image.

Actual Results

The range contains the bytes for the executable code but no longer includes data, debug information, or any other parts of the compilation image.

The source code for the method appears to only retrieve the text section.

Versions and Environment

Wasmtime version or commit: Wasmtime 40.0.0

Operating system: All

Architecture: All

Extra Info

We're using the image_size API in wasmtime-rb to inform the Ruby garbage collector about the size of the memory used for the anonymous mmap when creating a module.

It looks like the change in implementation was introduced here on line 975.

Wasmtime GitHub notifications bot (Jan 09 2026 at 19:57):

alexcrichton commented on issue #12284:

@jeffcharles would you be ok waiting for the 41.0.0 release in ~11 days, or would you prefer a 40.0.2 release with this fix?

Wasmtime GitHub notifications bot (Jan 09 2026 at 20:14):

jeffcharles commented on issue #12284:

I'm okay with waiting. We don't have anyone pressing us for the version 40 release of wasmtime-rb at the moment so we can probably just wait and cut a release for version 41.

Last updated: Feb 24 2026 at 06:21 UTC