Import uses the wrong module when function name is "write"

[ckaznocha]

When setting the target as WASI specifying a module to import a function named write, the generated wasm code will import "wasi_snapshot_preview1" "fd_write" rather than a function called write from the correct module.

Example go program with the incorrect import:

package main

//go:wasm-module my_module
//export foo
func foo() int // <-- Works correctly

//go:wasm-module my_module
//export write
func bar() int // <-- imports fd_write from wasi_snapshot_preview1

func main() {
    foo()
    bar()
}

Compiled using tinygo build -target=wasi -scheduler=none -wasm-abi=generic -o ./module.wasm main.go

Result after converting main.wasm to wat:

(module
  (type (;0;) (func (result i32)))
  (type (;1;) (func (param i32 i32 i32 i32) (result i32)))
  (type (;2;) (func (param i32 i32 i32) (result i32)))
  (type (;3;) (func))
  (type (;4;) (func (param i32 i32)))
  (import "my_module" "foo" (func $foo (type 0)))
  (import "wasi_snapshot_preview1" "fd_write" (func $__wasi_fd_write (type 1)))
  (func $memset (type 2) (param i32 i32 i32) (result i32)
    (local i32 i32 i32 i64)
    block  ;; label = @1
      local.get 2
      i32.eqz
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8
      local.get 2
      local.get 0
      i32.add
      local.tee 3
      i32.const -1
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 3
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=2
      local.get 0
      local.get 1
      i32.store8 offset=1
      local.get 3
      i32.const -3
      i32.add
      local.get 1
      i32.store8
      local.get 3
      i32.const -2
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 7
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=3
      local.get 3
      i32.const -4
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      i32.const 0
      local.get 0
      i32.sub
      i32.const 3
      i32.and
      local.tee 4
      i32.add
      local.tee 3
      local.get 1
      i32.const 255
      i32.and
      i32.const 16843009
      i32.mul
      local.tee 1
      i32.store
      local.get 3
      local.get 2
      local.get 4
      i32.sub
      i32.const -4
      i32.and
      local.tee 4
      i32.add
      local.tee 2
      i32.const -4
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=8
      local.get 3
      local.get 1
      i32.store offset=4
      local.get 2
      i32.const -8
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -12
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 25
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=24
      local.get 3
      local.get 1
      i32.store offset=20
      local.get 3
      local.get 1
      i32.store offset=16
      local.get 3
      local.get 1
      i32.store offset=12
      local.get 2
      i32.const -16
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -20
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -24
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -28
      i32.add
      local.get 1
      i32.store
      local.get 4
      local.get 3
      i32.const 4
      i32.and
      i32.const 24
      i32.or
      local.tee 5
      i32.sub
      local.tee 2
      i32.const 32
      i32.lt_u
      br_if 0 (;@1;)
      local.get 1
      i64.extend_i32_u
      local.tee 6
      i64.const 32
      i64.shl
      local.get 6
      i64.or
      local.set 6
      local.get 3
      local.get 5
      i32.add
      local.set 1
      loop  ;; label = @2
        local.get 1
        local.get 6
        i64.store
        local.get 1
        i32.const 24
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 16
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 8
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 32
        i32.add
        local.set 1
        local.get 2
        i32.const -32
        i32.add
        local.tee 2
        i32.const 31
        i32.gt_u
        br_if 0 (;@2;)
      end
    end
    local.get 0)
  (func $write (type 2) (param i32 i32 i32) (result i32)
    (local i32)
    global.get 0
    i32.const 16
    i32.sub
    local.tee 3
    global.set 0
    local.get 3
    local.get 2
    i32.store offset=12
    local.get 3
    local.get 1
    i32.store offset=8
    block  ;; label = @1
      block  ;; label = @2
        local.get 0
        local.get 3
        i32.const 8
        i32.add
        i32.const 1
        local.get 3
        i32.const 4
        i32.add
        call $__wasi_fd_write
        local.tee 0
        i32.eqz
        br_if 0 (;@2;)
        i32.const 0
        i32.const 8
        local.get 0
        local.get 0
        i32.const 76
        i32.eq
        select
        i32.store offset=65536
        i32.const -1
        local.set 0
        br 1 (;@1;)
      end
      local.get 3
      i32.load offset=4
      local.set 0
    end
    local.get 3
    i32.const 16
    i32.add
    global.set 0
    local.get 0)
  (func $_start (type 3)
    (local i32)
    i32.const 65540
    i32.const 0
    memory.size
    i32.const 16
    i32.shl
    i32.const 65540
    i32.sub
    i32.const 6
    i32.shr_u
    call $memset
    drop
    local.get 0
    local.get 0
    call $command-line-arguments.main)
  (func $command-line-arguments.main (type 4) (param i32 i32)
    call $foo
    drop
    call $write
    drop)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 2)
  (global (;0;) (mut i32) (i32.const 65536))
  (export "memory" (memory 0))
  (export "_start" (func $_start))
  (export "command-line-arguments.main" (func $command-line-arguments.main)))

For comparison, the same file but changing the //go:export directive to anything
other than write outputs the correct import:

package main

//go:wasm-module my_module
//export foo
func foo() int // <-- Works correctly

//go:wasm-module my_module
//export bar
func bar() int // <-- Works correctly

func main() {
    foo()
    bar()
}

wat output:

(module
  (type (;0;) (func (result i32)))
  (type (;1;) (func (param i32 i32 i32) (result i32)))
  (type (;2;) (func))
  (type (;3;) (func (param i32 i32)))
  (import "my_module" "foo" (func $foo (type 0)))
  (import "my_module" "bar" (func $bar (type 0)))
  (func $memset (type 1) (param i32 i32 i32) (result i32)
    (local i32 i32 i32 i64)
    block  ;; label = @1
      local.get 2
      i32.eqz
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8
      local.get 2
      local.get 0
      i32.add
      local.tee 3
      i32.const -1
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 3
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=2
      local.get 0
      local.get 1
      i32.store8 offset=1
      local.get 3
      i32.const -3
      i32.add
      local.get 1
      i32.store8
      local.get 3
      i32.const -2
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 7
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=3
      local.get 3
      i32.const -4
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      i32.const 0
      local.get 0
      i32.sub
      i32.const 3
      i32.and
      local.tee 4
      i32.add
      local.tee 3
      local.get 1
      i32.const 255
      i32.and
      i32.const 16843009
      i32.mul
      local.tee 1
      i32.store
      local.get 3
      local.get 2
      local.get 4
      i32.sub
      i32.const -4
      i32.and
      local.tee 4
      i32.add
      local.tee 2
      i32.const -4
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=8
      local.get 3
      local.get 1
      i32.store offset=4
      local.get 2
      i32.const -8
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -12
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 25
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=24
      local.get 3
      local.get 1
      i32.store offset=20
      local.get 3
      local.get 1
      i32.store offset=16
      local.get 3
      local.get 1
      i32.store offset=12
      local.get 2
      i32.const -16
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -20
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -24
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -28
      i32.add
      local.get 1
      i32.store
      local.get 4
      local.get 3
      i32.const 4
      i32.and
      i32.const 24
      i32.or
      local.tee 5
      i32.sub
      local.tee 2
      i32.const 32
      i32.lt_u
      br_if 0 (;@1;)
      local.get 1
      i64.extend_i32_u
      local.tee 6
      i64.const 32
      i64.shl
      local.get 6
      i64.or
      local.set 6
      local.get 3
      local.get 5
      i32.add
      local.set 1
      loop  ;; label = @2
        local.get 1
        local.get 6
        i64.store
        local.get 1
        i32.const 24
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 16
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 8
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 32
        i32.add
        local.set 1
        local.get 2
        i32.const -32
        i32.add
        local.tee 2
        i32.const 31
        i32.gt_u
        br_if 0 (;@2;)
      end
    end
    local.get 0)
  (func $_start (type 2)
    (local i32)
    i32.const 65536
    i32.const 0
    memory.size
    i32.const 16
    i32.shl
    i32.const 65536
    i32.sub
    i32.const 6
    i32.shr_u
    call $memset
    drop
    local.get 0
    local.get 0
    call $command-line-arguments.main)
  (func $command-line-arguments.main (type 3) (param i32 i32)
    call $foo
    drop
    call $bar
    drop)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 1)
  (global (;0;) (mut i32) (i32.const 65536))
  (export "memory" (memory 0))
  (export "_start" (func $_start))
  (export "command-line-arguments.main" (func $command-line-arguments.main)))

It also seems to import correctly when no module or export directive is set:

package main

//go:wasm-module my_module
//export foo
func foo() int // <-- Works correctly

func write() int // <-- imports from env

func main() {
    foo()
    write()
}

Gives:

(module
  (type (;0;) (func (result i32)))
  (type (;1;) (func (param i32 i32) (result i32)))
  (type (;2;) (func (param i32 i32 i32) (result i32)))
  (type (;3;) (func))
  (type (;4;) (func (param i32 i32)))
  (import "my_module" "foo" (func $foo (type 0)))
  (import "env" "command-line-arguments.write" (func $command-line-arguments.write (type 1)))
  (func $memset (type 2) (param i32 i32 i32) (result i32)
    (local i32 i32 i32 i64)
    block  ;; label = @1
      local.get 2
      i32.eqz
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8
      local.get 2
      local.get 0
      i32.add
      local.tee 3
      i32.const -1
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 3
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=2
      local.get 0
      local.get 1
      i32.store8 offset=1
      local.get 3
      i32.const -3
      i32.add
      local.get 1
      i32.store8
      local.get 3
      i32.const -2
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 7
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      local.get 1
      i32.store8 offset=3
      local.get 3
      i32.const -4
      i32.add
      local.get 1
      i32.store8
      local.get 2
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 0
      i32.const 0
      local.get 0
      i32.sub
      i32.const 3
      i32.and
      local.tee 4
      i32.add
      local.tee 3
      local.get 1
      i32.const 255
      i32.and
      i32.const 16843009
      i32.mul
      local.tee 1
      i32.store
      local.get 3
      local.get 2
      local.get 4
      i32.sub
      i32.const -4
      i32.and
      local.tee 4
      i32.add
      local.tee 2
      i32.const -4
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 9
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=8
      local.get 3
      local.get 1
      i32.store offset=4
      local.get 2
      i32.const -8
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -12
      i32.add
      local.get 1
      i32.store
      local.get 4
      i32.const 25
      i32.lt_u
      br_if 0 (;@1;)
      local.get 3
      local.get 1
      i32.store offset=24
      local.get 3
      local.get 1
      i32.store offset=20
      local.get 3
      local.get 1
      i32.store offset=16
      local.get 3
      local.get 1
      i32.store offset=12
      local.get 2
      i32.const -16
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -20
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -24
      i32.add
      local.get 1
      i32.store
      local.get 2
      i32.const -28
      i32.add
      local.get 1
      i32.store
      local.get 4
      local.get 3
      i32.const 4
      i32.and
      i32.const 24
      i32.or
      local.tee 5
      i32.sub
      local.tee 2
      i32.const 32
      i32.lt_u
      br_if 0 (;@1;)
      local.get 1
      i64.extend_i32_u
      local.tee 6
      i64.const 32
      i64.shl
      local.get 6
      i64.or
      local.set 6
      local.get 3
      local.get 5
      i32.add
      local.set 1
      loop  ;; label = @2
        local.get 1
        local.get 6
        i64.store
        local.get 1
        i32.const 24
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 16
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 8
        i32.add
        local.get 6
        i64.store
        local.get 1
        i32.const 32
        i32.add
        local.set 1
        local.get 2
        i32.const -32
        i32.add
        local.tee 2
        i32.const 31
        i32.gt_u
        br_if 0 (;@2;)
      end
    end
    local.get 0)
  (func $_start (type 3)
    (local i32)
    i32.const 65536
    i32.const 0
    memory.size
    i32.const 16
    i32.shl
    i32.const 65536
    i32.sub
    i32.const 6
    i32.shr_u
    call $memset
    drop
    local.get 0
    local.get 0
    call $command-line-arguments.main)
  (func $command-line-arguments.main (type 4) (param i32 i32)
    (local i32)
    call $foo
    drop
    local.get 2
    local.get 2
    call $command-line-arguments.write
    drop)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 1)
  (global (;0;) (mut i32) (i32.const 65536))
  (export "memory" (memory 0))
  (export "_start" (func $_start))
  (export "command-line-arguments.main" (func $command-line-arguments.main)))

[aykevl]

Well that's interesting. I suspect there is some interaction with wasi-libc. This might mean you cannot give a function a name that matches a libc name such as write because those names will link against wasi-libc instead of leaving them undefined during linking.

Maybe this is a wasi-ld bug, I'm not sure what the intended behavior is when the module name differs.

[fgsch]

Function names are per module so it should be possible to have multiple write across different imports.

#1643 might be related.

[deadprogram]

Now that #1661 has been merged, can someone please re-test this issue against the dev branch? Thank you.

[fgsch]

Confirmed. Revision dcff8b6 produces the expected imports.

[fgsch]

@deadprogram not sure if you are waiting for the reporter or someone else to test this but in my tests this is fixed.

[deadprogram]

Thanks @fgsch just tagged with label for next release, at which point it will get closed.

[fgsch]

@deadprogram ok. fwiw, the fix is already included in 0.17.0.

[deadprogram]

AH, in that case, closing. Thanks for clarifying that @fgsch