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Compiler out of stack on generic base trait impl restricted to a derived trait #5988
Description
Rustc runs out of stack on this program:
use std::io;
trait B {
fn f(&self);
}
trait T : B {
}
struct A;
impl<U: T> B for U {
fn f(&self) { io::println("Hey, I'm a T!"); }
}
impl T for A {
}
fn main() {
let a = A;
let br = &a as &B;
// let tr = &a as &T;
// let br = tr as &B;
br.f();
}The inheritance of trait T from B seemingly triggers the recursion: without it, the program compiles and runs fine.
P.S. The commented-out lines illustrate what I was actually trying to achieve: upcasting a trait pointer to the base trait. That didn't work for other reasons.
Activity
bblum commentedon Jul 3, 2013
A little more minimal:
The stack overflow is a cycle between
lookup_vtables,lookup_vtable, back tolookup_vtables, andeach_bound_trait_and_supertraits.bblum commentedon Jul 3, 2013
nominating well-covered milestone
graydon commentedon Aug 22, 2013
accepted for production-ready milestone
pnkfelix commentedon Mar 13, 2014
just a bug, assigning P-low.
japaric commentedon Nov 2, 2014
Both examples compile on:
@nikomatsakis Can we close this? Or should we add a test (if it's not covered in the test suite already)?
alexcrichton commentedon Nov 3, 2014
Flagging as needstest (just in case)
nikomatsakis commentedon Nov 4, 2014
Wacky. I don't think there is a test specifically covering this scenario.
rollup merge of rust-lang#19780: jakub-/e-needstest
rollup merge of rust-lang#19780: jakub-/e-needstest
Auto merge of rust-lang#5988 - camelid:patch-2, r=ebroto
Auto merge of rust-lang#13216 - DesmondWillowbrook:move_format_string…
Merge rust-lang#5988