Passing an array by reference does not work in a conditional expression

[rightfold]

When I compile the following program everything is fine:

extern fun foo{n: nat}(xs: &(@[string][n])): void = "ext#foo"
implement main0 () =
    let
        var xs = @[string]("foo", "bar")
        val () = foo(xs)
    in
        ()
    end

But when I compile this program, I get an error:

extern fun foo{n: nat}(xs: &(@[string][n])): void = "ext#foo"
implement main0 () =
    let
        var xs = @[string]("foo", "bar")
        val () = if true then foo(xs) else ()
    in
        ()
    end

/tmp/871893664/main.dats: 176(line=5, offs=44) -- 178(line=5, offs=46): error(3): mismatch of static terms (tyleq):
The actual term is: S2Ecst(string_type)
The needed term is: S2Ecst(ptr_type)

The only difference between the two programs is if true then ... else () around the call foo(xs).

I'm not sure what is causing this but it seems like a bug to be; the presence of a conditional expression shouldn't influence the type of xs.

This problem does not occur when foo takes the array by value. The problem also occurs when using array_v.

I'm using ATS/Postiats version 0.3.11.

[githwxi]

The typechecker could not figure out the so-called master type of 'xs'; it picked @[string?][2] by default.

You can specify it as follows:

var xs: @[string][2] = @string

On Tue, Jan 8, 2019 at 6:14 PM rightfold notifications@github.com wrote:

When I compile the following program everything is fine:

extern fun foo{n: nat}(xs: &(@[string][n])): void = "ext#foo"implement main0 () = let var xs = @string val () = foo(xs) in () end

But when I compile this program, I get an error:

extern fun foo{n: nat}(xs: &(@[string][n])): void = "ext#foo"implement main0 () = let var xs = @string val () = if true then foo(xs) else () in () end

/tmp/871893664/main.dats: 176(line=5, offs=44) -- 178(line=5, offs=46): error(3): mismatch of static terms (tyleq): The actual term is: S2Ecst(string_type) The needed term is: S2Ecst(ptr_type)

I'm not sure what is causing this but it seems like a bug to be; the presence of a conditional expression shouldn't influence the type of xs.

This problem does not occur when foo takes the array by value. The problem also occurs when using array_v.

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[rightfold]

Thank you, that did the trick.