librustc: Use *signed* extension when converting enums to floats.

Previously, constants used unsigned extension, while non-constants used
signed extension. This unifies both paths to use signed extension.

If this breaks your code, take a deep breath, go for a walk, and
consider why you're relying on the sign extension semantics of
enum-to-float casts.

Closes #8230.

[breaking-change]
This commit is contained in:
Patrick Walton 2014-06-09 20:39:20 -07:00
parent 907d961876
commit 1a381fa2d2
2 changed files with 36 additions and 1 deletions

View File

@ -503,7 +503,7 @@ fn const_expr_unadjusted(cx: &CrateContext, e: &ast::Expr,
let s = ty::type_is_signed(ety) as Bool; let s = ty::type_is_signed(ety) as Bool;
llvm::LLVMConstIntCast(iv, llty.to_ref(), s) llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
} }
expr::cast_float => llvm::LLVMConstUIToFP(iv, llty.to_ref()), expr::cast_float => llvm::LLVMConstSIToFP(iv, llty.to_ref()),
_ => cx.sess().bug("enum cast destination is not \ _ => cx.sess().bug("enum cast destination is not \
integral or float") integral or float")
} }

View File

@ -0,0 +1,35 @@
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// Tests that enum-to-float-casts do *signed* integer-to-float conversion.
enum E {
L0 = -1,
H0 = 1
}
enum F {
L1 = 1,
H1 = 0xFFFFFFFFFFFFFFFF
}
static C0: f32 = L0 as f32;
static C1: f32 = H1 as f32;
pub fn main() {
let a = L0 as f32;
let b = C0;
let c = H1 as f32;
let d = C1;
assert_eq!(a, -1.0f32);
assert_eq!(b, -1.0f32);
assert_eq!(c, -1.0f32);
assert_eq!(d, -1.0f32);
}