Unexported ifaces should export metadata anyway for cross-crate monomorphisation

Spent too long figuring out an ICE: "'lookup_item: id not found: 51905', /home/bblum/rust/src/rustc/metadata/decoder.rs:96".

Turns out I had defined an iface in libcore/task.rs to use in a polymorphic function. I had exported the function, but not the iface. Then when attempting to compile a program that linked against libcore, this failure arose from type_of() in trans/type_of.rs when trying to #debug-print the type, called from monomorphic_fn() in trans/base.rs.

As a workaround, exporting the iface makes the metadata lookup go through.

Maybe all enums need this treatment too?

Offhand it looks like a reachability bug, but I'll investigate.

@bblum

@bblum Do you have a test case for reproducing this?

Closing due to lack of test case; reopen if you have one.

foo.rs:

export foo;
iface local_data { }
impl <T> of local_data for @T { }

fn foo<T>(t: @T) -> local_data {
    t as local_data
}

foo.rc:

#[link(name = "foo", vers="0.0")];
#[crate_type = "lib"];

bar.rs:

import foo;
fn main() { foo::foo(@5); }

bar.rc:

use foo;

run rustc foo.rc; rustc -L . bar.rc

The ICE goes away if:

foo is made to return unit
foo is not polymorphic

Arguably the above should refuse to compile, because foo has in its signature a nonexported type.

Here is a variation that still crashes:

trait face { fn x() -> int; }
impl <T> of face for @T { fn x() -> int { 5 } }

fn foo<T>(t: @T) -> int {
    (t as face).x()
}

Doesn't seem to happen with enums. This works fine:

export foo;
impl x<T> for face<T> { fn x() -> int { 5 } }
enum face<T> = @T;

fn foo<T>(t: @T) -> int {
    face(t).x()
}

related #2313?

Seems like the fix for #2945 should fix this too, but I'll still check.

pretty sure 1528256 fixed this. the bug is gone, anyway.

Bump CBMC version to 5.91.0 (rust-lang#2733)

Merge pull request rust-lang#2733 from rust-lang/tshepang/normalize-p…

removing ctrl+r key binding fixes rust-lang#2733

Merge rust-lang#3362

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Unexported ifaces should export metadata anyway for cross-crate monomorphisation #2733

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Unexported ifaces should export metadata anyway for cross-crate monomorphisation #2733

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catamorphism commented on Jun 28, 2012

catamorphism commented on Jul 11, 2012

catamorphism commented on Jul 11, 2012

bblum commented on Jul 18, 2012

bblum commented on Jul 18, 2012

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catamorphism commented on Jul 20, 2012

bblum commented on Jul 23, 2012

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