Implement manual_clamp lint

1 files changed, 46 insertions, 0 deletions

diff --git a/src/docs/manual_clamp.txt b/src/docs/manual_clamp.txt
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+### What it does
+Identifies good opportunities for a clamp function from std or core, and suggests using it.
+
+### Why is this bad?
+clamp is much shorter, easier to read, and doesn't use any control flow.
+
+### Known issue(s)
+If the clamped variable is NaN this suggestion will cause the code to propagate NaN
+rather than returning either `max` or `min`.
+
+`clamp` functions will panic if `max < min`, `max.is_nan()`, or `min.is_nan()`.
+Some may consider panicking in these situations to be desirable, but it also may
+introduce panicking where there wasn't any before.
+
+### Examples
+```
+if input > max {
+    max
+} else if input < min {
+    min
+} else {
+    input
+}
+```
+
+```
+input.max(min).min(max)
+```
+
+```
+match input {
+    x if x > max => max,
+    x if x < min => min,
+    x => x,
+}
+```
+
+```
+let mut x = input;
+if x < min { x = min; }
+if x > max { x = max; }
+```
+Use instead:
+```
+input.clamp(min, max)
+```
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