'attempt to negate with overflow' with specific values

[Eijebong]

I updated float-cmp in librsvg and ran into this in the test suite. This only happens in debug mode.

fn main() {
    use float_cmp::ApproxEq;
    // -25.0 / 25.0 / 0.00390625
    println!("{:?}", (-25.0f64).approx_eq(25.0, (0.00390625, 1)));
}

thread 'main' panicked at 'attempt to negate with overflow', /builddir/build/BUILD/rustc-1.36.0-src/src/libcore/num/mod.rs:1972:21
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::_print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::continue_panic_fmt
   6: rust_begin_unwind
   7: core::panicking::panic_fmt
   8: core::panicking::panic
   9: core::num::<impl i64>::abs
             at /builddir/build/BUILD/rustc-1.36.0-src/src/libcore/num/mod.rs:1972
  10: <f64 as float_cmp::eq::ApproxEq>::approx_eq
             at /root/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/float-cmp-0.5.1/src/eq.rs:230
  11: bug_fl::main
             at src/main.rs:4
  12: std::rt::lang_start::{{closure}}
             at /builddir/build/BUILD/rustc-1.36.0-src/src/libstd/rt.rs:64
  13: std::panicking::try::do_call
  14: __rust_maybe_catch_panic
  15: std::rt::lang_start_internal
  16: std::rt::lang_start
             at /builddir/build/BUILD/rustc-1.36.0-src/src/libstd/rt.rs:64
  17: main
  18: __libc_start_main
  19: _start

[mikedilger]

Nice catch of an edge case. I'll work out a fix shortly.

[mikedilger]

Solved nicely with rust-lang/rust#59983 but that is still on nightly.

[mikedilger]

Fixed in 0.5.2