tmp

Author: AaronKutch

Diff for: testcrate/tests/conv.rs

@@ -4,12 +4,14 @@ macro_rules! i_to_f {
     ($($from:ty, $into:ty, $fn:ident);*;) => {
         $(
             fuzz(N, |x: $from| {
-                // This makes sure that the conversion produced the best rounding possible.
-                // This assumes that float to integer conversion is correct.
                 let f0 = x as $into;
-                let y_minus_ulp = <$into>::from_bits(f0.to_bits().wrapping_sub(1)) as $from;
-                let y = f0 as $from;
-                let y_plus_ulp = <$into>::from_bits(f0.to_bits().wrapping_add(1)) as $from;
+                let f1: $into = $fn(x);
+                // This makes sure that the conversion produced the best rounding possible, and does
+                // this independent of `x as $into` rounding correctly.
+                // This assumes that float to integer conversion is correct.
+                let y_minus_ulp = <$into>::from_bits(f1.to_bits().wrapping_sub(1)) as $from;
+                let y = f1 as $from;
+                let y_plus_ulp = <$into>::from_bits(f1.to_bits().wrapping_add(1)) as $from;
                 let error_minus = <$from as Int>::abs_diff(y_minus_ulp, x);
                 let error = <$from as Int>::abs_diff(y, x);
                 let error_plus = <$from as Int>::abs_diff(y_plus_ulp, x);
@@ -25,7 +27,7 @@ macro_rules! i_to_f {
                         "incorrect rounding by {}({}): {}, ({}, {}, {}), errors ({}, {}, {})",
                         stringify!($fn),
                         x,
-                        f0.to_bits(),
+                        f1.to_bits(),
                         y_minus_ulp,
                         y,
                         y_plus_ulp,
@@ -35,9 +37,14 @@ macro_rules! i_to_f {
                     );
                 }
                 // test against native conversion
-                let f1: $into = $fn(x);
                 if f0 != f1 {
-                    panic!("{}({}): expected: {}, found: {}", stringify!($fn), x, f0, f1);
+                    panic!(
+                        "{}({}): expected: {}, found: {}",
+                        stringify!($fn),
+                        x,
+                        f0.to_bits(),
+                        f1.to_bits()
+                    );
                 }
             });
         )*