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The wasmtime CLI does not support map<K, V> #14811

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Description

@alexcrichton

This input:

(component
  (core module $m
    (memory (export "memory") 1)
    (data (i32.const 16) "\01\00\00\00\02\00\00\00")
    (data (i32.const 32) "\10\00\00\00\01\00\00\00")
    (func (export "f") (result i32) i32.const 32)
    (func (export "realloc") (param i32 i32 i32 i32) (result i32) unreachable)
  )
  (core instance $i (instantiate $m))
  (func (export "f") (result (map u32 u32))
    (canon lift (core func $i "f") (memory (core memory $i "memory")) (realloc (core func $i "realloc"))))
)

panics with:

$ wasmtime -W component-model-map --invoke 'f()' repro/ret_map.wat

thread 'main' (29151) panicked at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasm-wave-0.258.3/src/writer.rs:171:42:
unsupported value type
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
zsh: IOT instruction (core dumped)  wasmtime -W component-model-map --invoke 'f()' repro/ret_map.wat

Activity

  1. added 4 commits that reference this issue on Oct 20, 2026
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  2. added 3 commits that reference this issue on Oct 21, 2026
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