Merge pull request #890 from frvannes16/fix/888-std-floats

fix(clippy1): Trigger approx_constant lint rule instead of downgraded float_cmp.

exercises/clippy/clippy1.rs

@@ -8,10 +8,16 @@
 
 // I AM NOT DONE
 
+use std::f32;
+
 fn main() {
-    let x = 1.2331f64;
+    let pi = 3.14f32;
-    let y = 1.2332f64;
+    let radius = 5.00f32;
-    if y != x {
+
-        println!("Success!");
+    let area = pi * f32::powi(radius, 2);
-    }
+
+    println!(
+        "The area of a circle with radius {:.2} is {:.5}!",
+        radius, area
+    )
 }

info.toml

@@ -906,15 +906,15 @@ name = "clippy1"
 path = "exercises/clippy/clippy1.rs"
 mode = "clippy"
 hint = """
-Not every floating point value can be represented exactly in binary values in
+Rust stores the highest precision version of any long or inifinite precision
-memory. Take a look at the description of 
+mathematical constants in the rust standard library.
-https://doc.rust-lang.org/stable/std/primitive.f32.html
+https://doc.rust-lang.org/stable/std/f32/consts/index.html
-When using the binary compare operators with floating points you won't compare
+
-the floating point values but the binary representation in memory. This is 
+We may be tempted to use our own approximations for certain mathematical constants,
-usually not what you would like to do. 
+but clippy recognizes those imprecise mathematical constants as a source of 
+potential error.
 See the suggestions of the clippy warning in compile output and use the
-machine epsilon value...
+appropriate replacement constant from std::f32::consts..."""
-https://doc.rust-lang.org/stable/std/primitive.f32.html#associatedconstant.EPSILON"""
 
 [[exercises]]
 name = "clippy2"