examples: async build failure

[vdice]

I'm seeing the following failure attempting to spin build the async example:

$ spin -V
spin 3.6.0-pre0 (91172989 2025-10-29)

$ spin build
Building component job with `cargo build --target wasm32-wasip2 --release`
   Compiling job v0.1.0 (/Users/vdice/code/github.com/spinframework/spin-trigger-command/examples/async)
error: linking with `wasm-component-ld` failed: exit status: 1
  |
  = note:  "wasm-component-ld" "-flavor" "wasm" "--export" "__main_void" "--export" "cabi_realloc" "--export" "spin-sdk-commit-unknown" "--export" "spin-sdk-language-rust" "--export" "spin-sdk-version-5-1" "-z" "stack-size=1048576" "--stack-first" "--allow-undefined" "--no-demangle" "<sysroot>/lib/rustlib/wasm32-wasip2/lib/self-contained/crt1-command.o" "<5 object files omitted>" "<sysroot>/lib/rustlib/wasm32-wasip2/lib/libpanic_abort-*.rlib" "/Users/vdice/code/github.com/spinframework/spin-trigger-command/examples/async/target/wasm32-wasip2/release/deps/{libspin_sdk-daa7e39c06415108,libpostgres_range-f36079c328778f75,libpostgres_types-d4ef6d0fb438b6e0,libpostgres_protocol-1accb76661d3511d,libstringprep-3915c03ba7d5c748,libunicode_properties-b6b179efc6d33d06,libunicode_normalization-4605f5716bbbf044,libtinyvec-714f1b3f65d8c5de,libtinyvec_macros-e3683324125df1b3,libunicode_bidi-05b56ebf4d507b7c,libsha2-e3d41103e048fb8b,librand-d08dadfbcfc9d26a,librand_chacha-22cbbeb59681eea9,libppv_lite86-ec9c9a9bd624edea,libzerocopy-d60d55563379c4a5,librand_core-fcb8c5b7d8f47ef3,libgetrandom-dc68862fec913b81,libwasi-42491ba05a428f10,libwit_bindgen-be390c800c212c2f,libhmac-20ce9bc6279d4121,libbase64-a3893d386dc712a9,libmd5-835217afd6d8eae8,libcfg_if-d04efcb978e0bf6c,libdigest-12c90346dde2c460,libsubtle-2e958363cae74820,libblock_buffer-b84b8f02eee9889f,libcrypto_common-babf46fd77ddfdf7,libgeneric_array-80a011c999302e15,libtypenum-0e558c4c11e75192,libbyteorder-bd1f636c289b124f,libfallible_iterator-18e62ad928f76b6f,librust_decimal-81b4c60040d315a0,libarrayvec-12e3180850de83ab,libuuid-06e35ac809e13608,libhttp-64ea4ba361222f25,libbytes-6189f0509e352470,libfnv-1cfa31f675d03145,libserde_json-71acc9f97bf1e676,libitoa-7e92cc1f8e0eae09,libryu-3f7186d2c55ba96f,libthiserror-650a45350f562100,libanyhow-3ddf8ce7ed34fa02,libwit_bindgen-ed9f9ecef1729595,libwit_bindgen_rt-6bec717a2d6a77cc,libchrono-1dd9304c6057786a,libnum_traits-eaef54bbd05ed75c,libroutefinder-c0f78c0eab17dc96,libsmartcow-99900d5bc45096e4,libsmartstring-e247f3be559a7876,libstatic_assertions-e53e1061dc46eaf7,libspin_executor-61926dcbea7dbbe9,libfutures-0c4a1b5f258c4356,libfutures_executor-3ca243f02ee054a1,libfutures_util-d67fbf570fa5c59d,libmemchr-5c4322039412cec0,libfutures_io-ef3983342e2d55e4,libslab-8f374defb58168ec,libfutures_channel-83c9833b429abfaa,libpin_project_lite-b31c811f8f53300e,libfutures_sink-5fcd21ef1659fb4b,libfutures_task-cbd6ce05bf004b8c,libpin_utils-00f917fbb49cac15,libfutures_core-9b3ce6ef61fcb180,libwasi-0083c8b4e0f33dce,libwit_bindgen_rt-3d8c9c504018443d,libbitflags-a191c15434324d18,libserde-37f4d6aea6e86d10}.rlib" "<sysroot>/lib/rustlib/wasm32-wasip2/lib/{libstd-*,libwasi-*,librustc_demangle-*,libstd_detect-*,libhashbrown-*,librustc_std_workspace_alloc-*,libminiz_oxide-*,libadler2-*,libunwind-*,libcfg_if-*,liblibc-*}.rlib" "-l" "c" "<sysroot>/lib/rustlib/wasm32-wasip2/lib/{librustc_std_workspace_core-*,liballoc-*,libcore-*,libcompiler_builtins-*}.rlib" "-l" "wit_bindgen_cabi_realloc" "-L" "/Users/vdice/code/github.com/spinframework/spin-trigger-command/examples/async/target/wasm32-wasip2/release/build/wit-bindgen-33f5245701e96cd4/out" "-L" "/Users/vdice/code/github.com/spinframework/spin-trigger-command/examples/async/target/wasm32-wasip2/release/build/wit-bindgen-rt-7dc94de5a7ad94ba/out" "-L" "/Users/vdice/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wit-bindgen-rt-0.24.0/src" "-L" "<sysroot>/lib/rustlib/wasm32-wasip2/lib/self-contained" "-o" "/Users/vdice/code/github.com/spinframework/spin-trigger-command/examples/async/target/wasm32-wasip2/release/deps/job-d3299c6c9eedab83.wasm" "--gc-sections" "-O3" "--strip-debug"
  = note: some arguments are omitted. use `--verbose` to show all linker arguments
  = note: error: failed to parse core wasm for componentization

          Caused by:
              0: updating metadata for section component-type:wit-bindgen:0.24.0:bindings:encoded worldrust-wasi-from-crates-io
              1: failed to merge WIT package sets together
              2: failed to merge package `rust:wasi` into existing copy
              3: failed to merge world `bindings`
              4: import `wasi:io/poll@0.2.0` not found in target world


error: could not compile `job` (bin "job") due to 1 previous error
Error: Build command for component job failed with status Exited(101)

[itowlson]

bindings.rs looks a bit weird: I am not sure where wit-bindgen:0.24.0 is coming from. I wonder if this is left over from a previous iteration that used cargo component or something? Maybe we should try removing bindings.rs and seeing if a plain Rust P2 build works?

[vdice]

Thanks @itowlson, it appears that was it.