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Switch to eval_const_expr_partial when check_match.rs checks for NaN.

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This commit is contained in:
Felix S. Klock II 2015-02-22 16:35:11 +01:00
parent e919f82da1
commit 5d950bd37d
1 changed files with 21 additions and 14 deletions
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35
src/librustc/middle/check_match.rs
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@ -13,7 +13,8 @@ use self::Usefulness::*;
use self::WitnessPreference::*;
use middle::const_eval::{compare_const_vals, const_bool, const_float, const_val};
use middle::const_eval::{const_expr_to_pat, eval_const_expr, lookup_const_by_id};
use middle::const_eval::{eval_const_expr, eval_const_expr_partial};
use middle::const_eval::{const_expr_to_pat, lookup_const_by_id};
use middle::def::*;
use middle::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Init};
use middle::expr_use_visitor::{JustWrite, LoanCause, MutateMode};
@ -229,13 +230,6 @@ fn check_expr(cx: &mut MatchCheckCtxt, ex: &ast::Expr) {
}
}
fn is_expr_const_nan(tcx: &ty::ctxt, expr: &ast::Expr) -> bool {
match eval_const_expr(tcx, expr) {
const_float(f) => f.is_nan(),
_ => false
}
}
fn check_for_bindings_named_the_same_as_variants(cx: &MatchCheckCtxt, pat: &Pat) {
ast_util::walk_pat(pat, |p| {
match p.node {
@ -269,13 +263,26 @@ fn check_for_bindings_named_the_same_as_variants(cx: &MatchCheckCtxt, pat: &Pat)
// Check that we do not match against a static NaN (#6804)
fn check_for_static_nan(cx: &MatchCheckCtxt, pat: &Pat) {
ast_util::walk_pat(pat, |p| {
match p.node {
ast::PatLit(ref expr) if is_expr_const_nan(cx.tcx, &**expr) => {
span_warn!(cx.tcx.sess, p.span, E0003,
"unmatchable NaN in pattern, \
use the is_nan method in a guard instead");
if let ast::PatLit(ref expr) = p.node {
match eval_const_expr_partial(cx.tcx, &**expr, None) {
Ok(const_float(f)) if f.is_nan() => {
span_warn!(cx.tcx.sess, p.span, E0003,
"unmatchable NaN in pattern, \
use the is_nan method in a guard instead");
}
Ok(_) => {}
Err(err) => {
let subspan = p.span.lo <= err.span.lo && err.span.hi <= p.span.hi;
cx.tcx.sess.span_err(err.span,
&format!("constant evaluation error: {}",
err.description().as_slice()));
if !subspan {
cx.tcx.sess.span_note(p.span,
"in pattern here")
}
}
}
_ => ()
}
true
});