Binary float literals sometimes "work"

[huonw]

fn main() {
    let x = 0bf;
    let x = 0b101f;
}

bin-float.rs:2:8: 2:9 warning: unused variable: `x` [-W unused-variable (default)]
bin-float.rs:2     let x = 0bf;
                       ^
bin-float.rs:3:8: 3:9 warning: unused variable: `x` [-W unused-variable (default)]
bin-float.rs:3     let x = 0b101f;
                       ^
rustc: /home/huon/rust/src/llvm/lib/Support/APFloat.cpp:2491: llvm::APFloat::opStatus llvm::APFloat::convertFromString(llvm::StringRef, llvm::APFloat::roundingMode): Assertion `!str.empty() && "Invalid string length"' failed.

(The assertion is from the 0bf.)

Also:

compiler instead. Type :help for help.
rusti> 0bf
<anon>:15:0: 15:1 error: unresolved name `f`.
<anon>:15 f;
          ^

Either they should be fully supported, or not at all.

[huonw]

Triage: still an issue, the following even runs without failing:

fn main() { assert_eq!(0b101f, 101.0) }

i.e. they're not even being read as binary.

[alexcrichton]

It looks like binary float literals were removed in 01cc9ec, and perhaps at some point later on we fixed rejecting these literals. Regardless, this is a real error now.

foo.rs:1:24: 1:32 error: binary float literal is not supported
foo.rs:1 fn main() { assert_eq!(0b101f64, 101.0) }
                                ^~~~~~~~