Global paths don't work in `match` at all #6449

huonw · 2013-05-13T11:43:36Z

fn main() {
    match Some(1i) {
        ::std::option::None => (),
        _ => ()
    }
}

causes

rust: task failed at 'Non-constant path in constant expr', /home/huon/rust/src/librustc/middle/const_eval.rs:245
/usr/local/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f2d23474c7b]
/usr/local/bin/../lib/librustrt.so(+0x2a7a9)[0x7f2d234857a9]
/usr/local/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7f2d23476c30]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys13begin_unwind_16_615cb041c655a976_07preE+0x63)[0x7f2d26dd9d93]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x123d22)[0x7f2d26dd9d22]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys14__extensions__9meth_89249fail_with17_ac9eb45dc42bd6906_07preE+0x6b)[0x7f2d26d1926b]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle10const_eval15eval_const_expr15_18e714080831846_07preE+0x1d9)[0x7f2d25260c59]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match11pat_ctor_id17_cae022f360f6f0546_07preE+0x41d)[0x7f2d256fd9bd]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match12missing_ctor15_1c83f67218d27c6_07preE+0x719)[0x7f2d256fec29]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match9is_useful17_171373a22e57e1326_07preE+0x4d0)[0x7f2d256fb260]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match10check_arms17_69fd16459bd67f826_07preE+0x17c)[0x7f2d256f8b3c]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match10check_expr17_cc26556e76f6d92b6_07preE+0x1fa)[0x7f2d256f656a]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x7250c5)[0x7f2d256f60c5]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a539f)[0x7f2d2547639f]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a5277)[0x7f2d25476277]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a5089)[0x7f2d25476089]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4aa508)[0x7f2d2547b508]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match8check_fn17_6a2b6ee6eacc23346_07preE+0xb4)[0x7f2d256f7c04]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x726ab9)[0x7f2d256f7ab9]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a333b)[0x7f2d2547433b]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a2dc5)[0x7f2d25473dc5]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a25f0)[0x7f2d254735f0]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x4a2435)[0x7f2d25473435]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x2d7881)[0x7f2d252a8881]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6middle11check_match11check_crate17_eabc483fea66f5e46_07preE+0x483)[0x7f2d256f59c3]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa3529b)[0x7f2d25a0629b]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0x7155b9)[0x7f2d256e65b9]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_rest17_9368fee59be894ab6_07preE+0x2115)[0x7f2d25a011b5]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver12compile_upto17_3cbff05fabc6d3166_07preE+0x192)[0x7f2d25a06852]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN6driver6driver13compile_input17_d8ffa027e111b5706_07preE+0x107)[0x7f2d25a06cd7]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN12run_compiler17_c7b6fbcba7c0cea46_07preE+0x2bbb)[0x7f2d25a3686b]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa7831e)[0x7f2d25a4931e]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa75ccc)[0x7f2d25a46ccc]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa6f6fc)[0x7f2d25a406fc]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa785f8)[0x7f2d25a495f8]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xecf45)[0x7f2d26da2f45]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x1690d8)[0x7f2d26e1f0d8]
/usr/local/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f2d23475624]
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /home/huon/rust/src/librustc/rustc.rc:355
/usr/local/bin/../lib/librustrt.so(_ZN9rust_task13begin_failureEPKcS1_m+0x4b)[0x7f2d23474c7b]
/usr/local/bin/../lib/librustrt.so(+0x2a7a9)[0x7f2d234857a9]
/usr/local/bin/../lib/librustrt.so(upcall_fail+0x1a0)[0x7f2d23476c30]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(_ZN3sys13begin_unwind_16_615cb041c655a976_07preE+0x63)[0x7f2d26dd9d93]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0x123e42)[0x7f2d26dd9e42]
/usr/local/bin/../lib/libcore-c3ca5d77d81b46c1-0.7-pre.so(+0xc3d04)[0x7f2d26d79d04]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN7monitor17_db1d451e7194e13d6_07preE+0x2415)[0x7f2d25a39e65]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(+0xa785f8)[0x7f2d25a495f8]
/usr/local/bin/../lib/librustc-c84825241471686d-0.7-pre.so(_ZN4main15_c4de63b748e03d6_07preE+0x69)[0x7f2d25a49259]
rustc(_rust_main+0x2e)[0x400bee]
/usr/local/bin/../lib/librustrt.so(_Z18task_start_wrapperP10spawn_args+0x24)[0x7f2d23475624]
rust: domain main @0xd11430 root task failed

Similarly,

fn main() {
    match Some(1i) {
        ::std::option::Some(1) => (),
        _ => ()
    }
}

is the same, except the actual error message is

rust: task failed at 'Unsupported constant expr', /home/huon/rust/src/librustc/middle/const_eval.rs:245

And

fn main() {
    match Some(1i) {
        ::std::option::Some(_) => (),
        _ => ()
    }
}

doesn't even parse

test.rs:3:29: 3:30 error: unexpected token: `_`
test.rs:3         ::std::option::Some(_) => (),

The versions without the leading :: work fine.

(Among other things, this makes syntax extensions harder/uglier than necessary.)

The text was updated successfully, but these errors were encountered:

brendanzab · 2013-05-13T12:11:34Z

use ::core::option::Some; doesn't work either. I don't know if this is related.

jdm · 2013-05-13T12:53:34Z

Nominating for feature complete.

brendanzab · 2013-05-16T07:10:44Z

This could be related: #6533

brendanzab · 2013-05-16T07:58:57Z

Interestingly I get the same error here, without any paths:

pub enum MouseButton {
    MOUSE_BUTTON_1 = 1,
    MOUSE_BUTTON_2 = 2,
    MOUSE_BUTTON_3 = 3,
    MOUSE_BUTTON_4 = 4,
    MOUSE_BUTTON_5 = 5,
    MOUSE_BUTTON_6 = 6,
    MOUSE_BUTTON_7 = 7,
    MOUSE_BUTTON_8 = 8,
}

pub static MOUSE_BUTTON_LEFT    : MouseButton = MOUSE_BUTTON_1;
pub static MOUSE_BUTTON_RIGHT   : MouseButton = MOUSE_BUTTON_2;
pub static MOUSE_BUTTON_MIDDLE  : MouseButton = MOUSE_BUTTON_3;

fn mouse_button_to_str(button: MouseButton) -> ~str {
    match button {
        MOUSE_BUTTON_LEFT     => ~"Left",
        MOUSE_BUTTON_RIGHT    => ~"Right",
        MOUSE_BUTTON_MIDDLE   => ~"Middle",
        MOUSE_BUTTON_4        => ~"4",
        MOUSE_BUTTON_5        => ~"5",
        MOUSE_BUTTON_6        => ~"6",
        MOUSE_BUTTON_7        => ~"7",
        MOUSE_BUTTON_8        => ~"8",
    }
}

fn main() {}

Error:

$ RUST_LOG=rustc=1,::rt::backtrace rustc enum-match-ice.rs
rust: task failed at 'Non-constant path in constant expr', /-------/rust/src/librustc/middle/const_eval.rs:245
error: internal compiler error: unexpected failure
note: the compiler hit an unexpected failure path. this is a bug
note: try running with RUST_LOG=rustc=1,::rt::backtrace to get further details and report the results to github.com/mozilla/rust/issues
rust: task failed at 'explicit failure', /------/rust/src/librustc/rustc.rc:355
rust: domain main @0x7f8b7080ba10 root task failed

jdm · 2013-05-16T13:58:11Z

@bjz, I would file that as a new issue.

graydon · 2013-05-16T16:45:26Z

accepted for production-ready milestone

pnkfelix · 2013-07-02T12:17:19Z

linking to #6143 for unified tracking of resolve

catamorphism · 2013-09-02T23:43:26Z

Bug triage. Milestone looks right.

wilkie · 2014-01-05T16:53:28Z

Recently, referring to https://gist.github.com/wilkie/157110f8387ecfce021e I get an error not already mentioned here:

bug.rs:10:7: 10:9 error: unexpected token: `::`
bug.rs:10       ::foo::X => {},

Using a use statement to avoid having to begin with a '::' does work as a workaround, but it is still not obvious that one cannot explicitly scope something within a match.

pnkfelix · 2014-03-20T20:24:21Z

Just a bug, not a 1.0 blocker.

P-high, not 1.0.

This replaces some `if`s with `match`es. This was originally not possible because using a global path in a match statement caused a "non-constant path in constant expr" ICE. The issue is long since closed, though you still hit it (as an error now, not an ICE) if you try to generate match patterns using pat_lit(expr_path). But it works when constructing the patterns more carefully.

needless_borrow: print the type in the lint message changelog: needless_borrow: print type in lint message

brendanzab mentioned this issue May 16, 2013

ICE: 'Non-constant path in constant expr' when matching on enum constants #6538

Closed

huonw mentioned this issue May 17, 2013

Absolute paths in enum variant names cause "a variety of fun errors" #5269

Closed

huonw mentioned this issue Jan 26, 2014

surprises in resolve #6143

Closed

pnkfelix added P-high and removed P-high-untriaged labels Mar 20, 2014

pnkfelix modified the milestone: 1.0 Mar 20, 2014

alexcrichton removed the I-ICE label May 21, 2014

alexcrichton closed this as completed in fd88e2b May 22, 2014

flip1995 pushed a commit to flip1995/rust that referenced this issue Dec 20, 2020

Auto merge of rust-lang#6449 - matthiaskrgr:needless_borrow_ty, r=ebroto

6b2b357

needless_borrow: print the type in the lint message changelog: needless_borrow: print type in lint message

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Global paths don't work in `match` at all #6449

Global paths don't work in `match` at all #6449

huonw commented May 13, 2013

brendanzab commented May 13, 2013

jdm commented May 13, 2013

brendanzab commented May 16, 2013

brendanzab commented May 16, 2013

jdm commented May 16, 2013

graydon commented May 16, 2013

pnkfelix commented Jul 2, 2013

catamorphism commented Sep 2, 2013

wilkie commented Jan 5, 2014

pnkfelix commented Mar 20, 2014

Global paths don't work in match at all #6449

Global paths don't work in match at all #6449

Comments

huonw commented May 13, 2013

brendanzab commented May 13, 2013

jdm commented May 13, 2013

brendanzab commented May 16, 2013

brendanzab commented May 16, 2013

jdm commented May 16, 2013

graydon commented May 16, 2013

pnkfelix commented Jul 2, 2013

catamorphism commented Sep 2, 2013

wilkie commented Jan 5, 2014

pnkfelix commented Mar 20, 2014

Global paths don't work in `match` at all #6449

Global paths don't work in `match` at all #6449