Add tests for range_plus_one and range_minus_one

Author: niklasf

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(..);
+}