Add tests for range_plus_one and range_minus_one

tests/ui/range_plus_minus_one.rs

@@ -0,0 +1,34 @@
+#![feature(inclusive_range_syntax)]
+
+fn f() -> usize {
+    42
+}
+
+#[warn(range_plus_one)]
+fn main() {
+    for _ in 0..2 { }
+    for _ in 0..=2 { }
+
+    for _ in 0..3+1 { }
+    for _ in 0..=3+1 { }
+
+    for _ in 0..1+5 { }
+    for _ in 0..=1+5 { }
+
+    for _ in 1..1+1 { }
+    for _ in 1..=1+1 { }
+
+    for _ in 0..13+13 { }
+    for _ in 0..=13-7 { }
+
+    for _ in 0..(1+f()) { }
+    for _ in 0..=(1+f()) { }
+
+    let _ = ..11-1;
+    let _ = ..=11-1;
+    let _ = ..=(11-1);
+    let _ = (f()+1)..(f()+1);
+
+    let mut vec: Vec<()> = std::vec::Vec::new();
+    vec.drain(..);
+}

tests/ui/range_plus_minus_one.stderr

@@ -0,0 +1,67 @@
+error: an inclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:12:14
+   |
+12 |     for _ in 0..3+1 { }
+   |              ------
+   |              |
+   |              help: use: `0..=3`
+   |              in this macro invocation
+   |
+   = note: `-D range-plus-one` implied by `-D warnings`
+
+error: an inclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:15:14
+   |
+15 |     for _ in 0..1+5 { }
+   |              ------
+   |              |
+   |              help: use: `0..=5`
+   |              in this macro invocation
+
+error: an inclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:18:14
+   |
+18 |     for _ in 1..1+1 { }
+   |              ------
+   |              |
+   |              help: use: `1..=1`
+   |              in this macro invocation
+
+error: an inclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:24:14
+   |
+24 |     for _ in 0..(1+f()) { }
+   |              ----------
+   |              |
+   |              help: use: `0..=f()`
+   |              in this macro invocation
+
+error: an exclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:28:13
+   |
+28 |     let _ = ..=11-1;
+   |             -------
+   |             |
+   |             help: use: `..11`
+   |             in this macro invocation
+   |
+   = note: `-D range-minus-one` implied by `-D warnings`
+
+error: an exclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:29:13
+   |
+29 |     let _ = ..=(11-1);
+   |             ---------
+   |             |
+   |             help: use: `..11`
+   |             in this macro invocation
+
+error: an inclusive range would be more readable
+  --> $DIR/range_plus_minus_one.rs:30:13
+   |
+30 |     let _ = (f()+1)..(f()+1);
+   |             ----------------
+   |             |
+   |             help: use: `(f()+1)..=f()`
+   |             in this macro invocation
+