Parsing "+" or "-" to f32/f64 on nightly

[yoeljacobsen]

I tried this code:

match "+".parse::<f32>() {
  Ok(v) => println!("f32 OK: {}", v),
  Err(e) => println!("f32 Error: {}", e) 
}

match "-".parse::<f64>() {
  Ok(v) => println!("f64 OK: {}", v),
  Err(e) => println!("f64 Error: {}", e) 
}

I expected to see this happen: "Error: invalid float literal"

Instead, this happened: OK: 0

It seems the "leading +" and "leading -" is broken.

Further, with i32 and i64 is emits an error but IMO an incorrect one:

"cannot parse integer from empty string"

I would expect: "Invalid integer literal"

Meta

rustc --version --verbose:

rustc 1.5.0-nightly (81b3b27 2015-10-11)
binary: rustc
commit-hash: 81b3b27
commit-date: 2015-10-11
host: x86_64-unknown-linux-gnu
release: 1.5.0-nightly

[hanna-kruppe]

Oh my, the float part is embarrassing. Preparing a fix right now.

[alexcrichton]

Thanks for taking a look @rkruppe! Looks like this is working as expected on stable and has leaked into beta/nightly, so tagging as such.

[hanna-kruppe]

Yes, this is a bug (not checking for empty strings in the right places) of the dec2flt code. The bug is also in beta, so the PR (which I'll file very soon) should probably be backported to beta.