Auto merge of #43325 - ollie27:overflowing_literals, r=arielb1

Fix overflowing_literals lint for large f32s

Float literals need to be parsed as the correct type so they can be
rounded correctly.

Author: bors

src/libcore/num/f32.rs

@@ -10,8 +10,7 @@
 
 //! Operations and constants for 32-bits floats (`f32` type)
 
-// FIXME: MIN_VALUE and MAX_VALUE literals are parsed as -inf and inf #14353
-#![allow(overflowing_literals)]
+#![cfg_attr(stage0, allow(overflowing_literals))]
 
 #![stable(feature = "rust1", since = "1.0.0")]
 

src/libcore/num/f64.rs

@@ -10,9 +10,6 @@
 
 //! Operations and constants for 64-bits floats (`f64` type)
 
-// FIXME: MIN_VALUE and MAX_VALUE literals are parsed as -inf and inf #14353
-#![allow(overflowing_literals)]
-
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use intrinsics;

src/librustc_lint/types.rs

@@ -173,18 +173,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
                         }
                     }
                     ty::TyFloat(t) => {
-                        let (min, max) = float_ty_range(t);
-                        let lit_val: f64 = match lit.node {
+                        let is_infinite = match lit.node {
                             ast::LitKind::Float(v, _) |
                             ast::LitKind::FloatUnsuffixed(v) => {
-                                match v.as_str().parse() {
-                                    Ok(f) => f,
-                                    Err(_) => return,
+                                match t {
+                                    ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
+                                    ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
                                 }
                             }
                             _ => bug!(),
                         };
-                        if lit_val < min || lit_val > max {
+                        if is_infinite == Ok(true) {
                             cx.span_lint(OVERFLOWING_LITERALS,
                                          e.span,
                                          &format!("literal out of range for {:?}", t));
@@ -242,13 +241,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
             }
         }
 
-        fn float_ty_range(float_ty: ast::FloatTy) -> (f64, f64) {
-            match float_ty {
-                ast::FloatTy::F32 => (f32::MIN as f64, f32::MAX as f64),
-                ast::FloatTy::F64 => (f64::MIN, f64::MAX),
-            }
-        }
-
         fn int_ty_bits(int_ty: ast::IntTy, target_int_ty: ast::IntTy) -> u64 {
             match int_ty {
                 ast::IntTy::Is => int_ty_bits(target_int_ty, target_int_ty),

src/test/compile-fail/lint-type-overflow2.rs

@@ -17,8 +17,8 @@ fn main() {
     let x2: i8 = --128; //~ error: literal out of range for i8
     //~^ error: attempt to negate with overflow
 
-    let x = -3.40282348e+38_f32; //~ error: literal out of range for f32
-    let x =  3.40282348e+38_f32; //~ error: literal out of range for f32
+    let x = -3.40282357e+38_f32; //~ error: literal out of range for f32
+    let x =  3.40282357e+38_f32; //~ error: literal out of range for f32
     let x = -1.7976931348623159e+308_f64; //~ error: literal out of range for f64
     let x =  1.7976931348623159e+308_f64; //~ error: literal out of range for f64
 }

src/test/run-pass/big-literals.rs

@@ -8,9 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-
-#![feature(core)]
-
 // Catch mistakes in the overflowing literals lint.
 #![deny(overflowing_literals)]
 
@@ -21,4 +18,9 @@ pub fn main() {
     assert_eq!(18446744073709551615, (!0 as u64));
 
     assert_eq!((-2147483648i32).wrapping_sub(1), 2147483647);
+
+    assert_eq!(-3.40282356e+38_f32, ::std::f32::MIN);
+    assert_eq!(3.40282356e+38_f32, ::std::f32::MAX);
+    assert_eq!(-1.7976931348623158e+308_f64, ::std::f64::MIN);
+    assert_eq!(1.7976931348623158e+308_f64, ::std::f64::MAX);
 }