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auto merge of #5890 : youknowone/rust/const-eval, r=catamorphism

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This will help not to meet confusing errors.
In issue #5873, the error was "expected constant expr for vector length: Can't cast str to int".
It was originally "expected constant expr for vector length: Non-constant path in constant expr" (though still invalid error).
This patch make the original error to be printed.
This commit is contained in:
bors 2013-04-16 12:48:56 -07:00
commit 07e087bf31
1 changed files with 24 additions and 25 deletions
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47
src/librustc/middle/const_eval.rs
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@ -371,34 +371,33 @@ pub fn eval_const_expr_partial(tcx: middle::ty::ctxt, e: @expr)
expr_cast(base, _) => {
let ety = ty::expr_ty(tcx, e);
let base = eval_const_expr_partial(tcx, base);
match /*bad*/copy base {
Err(_) => base,
Ok(val) => {
match ty::get(ety).sty {
ty::ty_float(_) => {
match base {
Ok(const_uint(u)) => Ok(const_float(u as f64)),
Ok(const_int(i)) => Ok(const_float(i as f64)),
Ok(const_float(_)) => base,
_ => Err(~"Can't cast float to str")
}
}
ty::ty_uint(_) => {
match base {
Ok(const_uint(_)) => base,
Ok(const_int(i)) => Ok(const_uint(i as u64)),
Ok(const_float(f)) => Ok(const_uint(f as u64)),
_ => Err(~"Can't cast str to uint")
}
}
ty::ty_int(_) | ty::ty_bool => {
match base {
Ok(const_uint(u)) => Ok(const_int(u as i64)),
Ok(const_int(_)) => base,
Ok(const_float(f)) => Ok(const_int(f as i64)),
_ => Err(~"Can't cast str to int")
}
}
ty::ty_float(_) => match val {
const_uint(u) => Ok(const_float(u as f64)),
const_int(i) => Ok(const_float(i as f64)),
const_float(_) => base,
_ => Err(~"Can't cast float to str"),
},
ty::ty_uint(_) => match val {
const_uint(_) => base,
const_int(i) => Ok(const_uint(i as u64)),
const_float(f) => Ok(const_uint(f as u64)),
_ => Err(~"Can't cast str to uint"),
},
ty::ty_int(_) | ty::ty_bool => match val {
const_uint(u) => Ok(const_int(u as i64)),
const_int(_) => base,
const_float(f) => Ok(const_int(f as i64)),
_ => Err(~"Can't cast str to int"),
},
_ => Err(~"Can't cast this type")
}
}
}
}
expr_path(_) => {
match lookup_const(tcx, e) {
Some(actual_e) => eval_const_expr_partial(tcx, actual_e),