1 files changed, 78 insertions, 0 deletions
diff --git a/tests/ui/rfc-2497-if-let-chains/irrefutable-lets.rs b/tests/ui/rfc-2497-if-let-chains/irrefutable-lets.rs
new file mode 100644
index 00000000000..9afb6853b36
--- /dev/null
+++ b/tests/ui/rfc-2497-if-let-chains/irrefutable-lets.rs
@@ -0,0 +1,78 @@
+// revisions: allowed disallowed
+//[allowed] check-pass
+
+#![feature(if_let_guard, let_chains)]
+#![cfg_attr(allowed, allow(irrefutable_let_patterns))]
+#![cfg_attr(disallowed, deny(irrefutable_let_patterns))]
+
+use std::ops::Range;
+
+fn main() {
+    let opt = Some(None..Some(1));
+
+    if let first = &opt && let Some(ref second) = first && let None = second.start {}
+    //[disallowed]~^ ERROR leading irrefutable pattern in let chain
+
+    // No lint as the irrefutable pattern is surrounded by other stuff
+    if 4 * 2 == 0 && let first = &opt && let Some(ref second) = first && let None = second.start {}
+
+    if let first = &opt && let (a, b) = (1, 2) {}
+    //[disallowed]~^ ERROR irrefutable `if let` patterns
+
+    if let first = &opt && let Some(ref second) = first && let None = second.start && let v = 0 {}
+    //[disallowed]~^ ERROR leading irrefutable pattern in let chain
+    //[disallowed]~^^ ERROR trailing irrefutable pattern in let chain
+
+    if let Some(ref first) = opt && let second = first && let _third = second {}
+    //[disallowed]~^ ERROR trailing irrefutable patterns in let chain
+
+    if let Range { start: local_start, end: _ } = (None..Some(1)) && let None = local_start {}
+    //[disallowed]~^ ERROR leading irrefutable pattern in let chain
+
+    if let (a, b, c) = (Some(1), Some(1), Some(1)) && let None = Some(1) {}
+    //[disallowed]~^ ERROR leading irrefutable pattern in let chain
+
+    if let first = &opt && let None = Some(1) {}
+    //[disallowed]~^ ERROR leading irrefutable pattern in let chain
+
+    if let Some(ref first) = opt
+        && let Range { start: local_start, end: _ } = first
+        && let None = local_start {
+    }
+
+    match opt {
+        Some(ref first) if let second = first && let _third = second && let v = 4 + 4 => {},
+        //[disallowed]~^ ERROR irrefutable `if let` guard patterns
+        _ => {}
+    }
+
+    // No error about leading irrefutable patterns: the expr on the rhs might
+    // use the bindings created by the match.
+    match opt {
+        Some(ref first) if let Range { start: local_start, end: _ } = first
+            && let None = local_start => {},
+        _ => {}
+    }
+
+    match opt {
+        Some(ref first) if let Range { start: Some(_), end: local_end } = first
+            && let v = local_end && let w = v => {},
+        //[disallowed]~^ ERROR trailing irrefutable patterns in let chain
+        _ => {}
+    }
+
+    // No error, despite the prefix being irrefutable: moving out could change the behaviour,
+    // due to possible side effects of the operation.
+    while let first = &opt && let Some(ref second) = first && let None = second.start {}
+
+    while let first = &opt && let (a, b) = (1, 2) {}
+    //[disallowed]~^ ERROR irrefutable `while let` patterns
+
+    while let Some(ref first) = opt && let second = first && let _third = second {}
+    //[disallowed]~^ ERROR trailing irrefutable patterns in let chain
+
+    while let Some(ref first) = opt
+        && let Range { start: local_start, end: _ } = first
+        && let None = local_start {
+    }
+}