Stream: git-wasmtime

Topic: wasmtime / issue #11849 Build via C/API via cargo fails t...

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 08:55):

adv-sw edited issue #11849:

Test Case

Could build the host project in here, but it's not necessary - issue is build system missing an entry.
http://advance-software.com/misc/test_breakpoint.zip

Steps to Reproduce

Pull clear tree or delete target directory from your current one.
cargo build -p wasmtime-c-api --release

Expected Results

wasm C API apps build

Actual Results

wasmtime\crates\c-api\include\wasi.h(12,10): error C1083: Cannot open include file: 'wasmtime/conf.h': No such file or directory

Versions and Environment

Wasmtime version or commit: trunk

Operating system: Windows

Architecture: x86-64

Extra Info

Anything else you'd like to add?

Expect this is generated correctly when cmake is used as conf.h.in file is present.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 16:36):

cfallin closed issue #11849:

Test Case

Could build the host project in here, but it's not necessary - issue is build system missing an entry.
http://advance-software.com/misc/test_breakpoint.zip

Steps to Reproduce

Pull clear tree or delete target directory from your current one.
cargo build -p wasmtime-c-api --release

Expected Results

wasm C API apps build

Actual Results

wasmtime\crates\c-api\include\wasi.h(12,10): error C1083: Cannot open include file: 'wasmtime/conf.h': No such file or directory

Versions and Environment

Wasmtime version or commit: trunk

Operating system: Windows

Architecture: x86-64

Extra Info

Anything else you'd like to add?

Expect this is generated correctly when cmake is used as conf.h.in file is present.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 16:36):

cfallin commented on issue #11849:

Please see the documentation here in the README for c-api, which is also linked from our documentation on building Wasmtime:

To use Wasmtime from a C or C++ project, you must have CMake and a Rust toolchain installed.

From the root of the Wasmtime repository, run the following commands:
$ cmake -S crates/c-api -B target/c-api --install-prefix "$(pwd)/artifacts" $ cmake --build target/c-api $ cmake --install target/c-api

In other words, using the C API requires building with CMake. Thus, this is working as intended, and I will close the issue.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 19:08):

adv-sw commented on issue #11849:

Seems unnecessarily complex. cmake to convert a whole 1 header file which could just be shipped as is with sensible defaults.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 19:12):

adv-sw edited a comment on issue #11849:

Seems unnecessarily complex. cmake to convert a whole 1 header file which could just be shipped as is with sensible defaults.

from the root : cargo build -p wasmtime-c-api

works fine with the exception of that one header file.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 19:14):

bjorn3 commented on issue #11849:

Cmake isn't just used for the header file, but also to build a proper C dynamic library with rpath on ELF, correct install name on macOS, and in case of building it a static library it helps with telling the linker to link all necessary system libraries.

view this post on Zulip Wasmtime GitHub notifications bot (Oct 14 2025 at 19:22):

adv-sw commented on issue #11849:

thanks bjorn3, so how to build static lib the official way, please. we digress, but essentially this is the how to build c-api properly issue.

Docs state :

These commands will produce the following files:
artifacts/lib/libwasmtime.{a,lib}: Static Wasmtime library. Exact extension depends on your operating system.
artifacts/lib/libwasmtime.{so,dylib,dll}: Dynamic Wasmtime library. Exact extension depends on your operating system.
artifacts/include/**.{h,hh}: Header files for working with Wasmtime.

On Windows, we get wasmtime.lib (static) or wasmtime.dll & wasmtime.dll.lib (dynamic)
depending on whether building statically or dynamically.

I figured out to build static by setting these env vars before building but unsure that's the official way or even if complete.
set WASMTIME_STATIC_LIB=1
set WASMTIME_STATIC=1

Last updated: Dec 06 2025 at 06:05 UTC