Merge commit 'b52fb5234cd7c11ecfae51897a6f7fa52e8777fc' into clippyup

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diff --git a/src/docs/float_cmp_const.txt b/src/docs/float_cmp_const.txt
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+### What it does
+Checks for (in-)equality comparisons on floating-point
+value and constant, except in functions called `*eq*` (which probably
+implement equality for a type involving floats).
+
+### Why is this bad?
+Floating point calculations are usually imprecise, so
+asking if two values are *exactly* equal is asking for trouble. For a good
+guide on what to do, see [the floating point
+guide](http://www.floating-point-gui.de/errors/comparison).
+
+### Example
+```
+let x: f64 = 1.0;
+const ONE: f64 = 1.00;
+
+if x == ONE { } // where both are floats
+```
+
+Use instead:
+```
+let error_margin = f64::EPSILON; // Use an epsilon for comparison
+// Or, if Rust <= 1.42, use `std::f64::EPSILON` constant instead.
+// let error_margin = std::f64::EPSILON;
+if (x - ONE).abs() < error_margin { }
+```
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