Add if let tests

tests/ui/nll/match-cfg-fake-edges.rs

@@ -8,20 +8,34 @@ fn all_patterns_are_tested() {
  // Even though `x` is never actually moved out of, we don't want borrowck results to be based on
  // whether MIR lowering reveals which patterns are unreachable.
  let x = String::new();
- let _ = match true {
+ match true {
  _ => {},
  _ => drop(x),
- };
+ }
  // Borrowck must not know the second arm is never run.
  drop(x); //~ ERROR use of moved value
 
+ let x = String::new();
+ if let _ = true { //~ WARN irrefutable
+ } else {
+ drop(x)
+ }
+ // Borrowck must not know the else branch is never run.
+ drop(x); //~ ERROR use of moved value
+
  let x = (String::new(), String::new());
  match x {
  (y, _) | (_, y) => (),
  }
  &x.0; //~ ERROR borrow of moved value
  // Borrowck must not know the second pattern never matches.
  &x.1; //~ ERROR borrow of moved value
+
+ let x = (String::new(), String::new());
+ let ((y, _) | (_, y)) = x;
+ &x.0; //~ ERROR borrow of moved value
+ // Borrowck must not know the second pattern never matches.
+ &x.1; //~ ERROR borrow of moved value
 }
 
 #[rustfmt::skip]

tests/ui/nll/match-cfg-fake-edges.stderr

@@ -1,3 +1,13 @@
+warning: irrefutable `if let` pattern
+ --> $DIR/match-cfg-fake-edges.rs:19:8
+ |
+LL | if let _ = true {
+ | ^^^^^^^^^^^^
+ |
+ = note: this pattern will always match, so the `if let` is useless
+ = help: consider replacing the `if let` with a `let`
+ = note: `#[warn(irrefutable_let_patterns)]` on by default
+
 error[E0382]: use of moved value: `x`
  --> $DIR/match-cfg-fake-edges.rs:16:10
  |
@@ -15,8 +25,25 @@ help: consider cloning the value if the performance cost is acceptable
 LL | _ => drop(x.clone()),
  | ++++++++
 
+error[E0382]: use of moved value: `x`
+ --> $DIR/match-cfg-fake-edges.rs:24:10
+ |
+LL | let x = String::new();
+ | - move occurs because `x` has type `String`, which does not implement the `Copy` trait
+...
+LL | drop(x)
+ | - value moved here
+...
+LL | drop(x);
+ | ^ value used here after move
+ |
+help: consider cloning the value if the performance cost is acceptable
+ |
+LL | drop(x.clone())
+ | ++++++++
+
 error[E0382]: borrow of moved value: `x.0`
- --> $DIR/match-cfg-fake-edges.rs:22:5
+ --> $DIR/match-cfg-fake-edges.rs:30:5
  |
 LL | (y, _) | (_, y) => (),
  | - value moved here
@@ -31,7 +58,7 @@ LL | (ref y, _) | (_, y) => (),
  | +++
 
 error[E0382]: borrow of moved value: `x.1`
- --> $DIR/match-cfg-fake-edges.rs:24:5
+ --> $DIR/match-cfg-fake-edges.rs:32:5
  |
 LL | (y, _) | (_, y) => (),
  | - value moved here
@@ -45,8 +72,37 @@ help: borrow this binding in the pattern to avoid moving the value
 LL | (y, _) | (_, ref y) => (),
  | +++
 
+error[E0382]: borrow of moved value: `x.0`
+ --> $DIR/match-cfg-fake-edges.rs:36:5
+ |
+LL | let ((y, _) | (_, y)) = x;
+ | - value moved here
+LL | &x.0;
+ | ^^^^ value borrowed here after move
+ |
+ = note: move occurs because `x.0` has type `String`, which does not implement the `Copy` trait
+help: borrow this binding in the pattern to avoid moving the value
+ |
+LL | let ((ref y, _) | (_, y)) = x;
+ | +++
+
+error[E0382]: borrow of moved value: `x.1`
+ --> $DIR/match-cfg-fake-edges.rs:38:5
+ |
+LL | let ((y, _) | (_, y)) = x;
+ | - value moved here
+...
+LL | &x.1;
+ | ^^^^ value borrowed here after move
+ |
+ = note: move occurs because `x.1` has type `String`, which does not implement the `Copy` trait
+help: borrow this binding in the pattern to avoid moving the value
+ |
+LL | let ((y, _) | (_, ref y)) = x;
+ | +++
+
 error[E0381]: used binding `x` is possibly-uninitialized
- --> $DIR/match-cfg-fake-edges.rs:58:19
+ --> $DIR/match-cfg-fake-edges.rs:72:19
  |
 LL | let x;
  | - binding declared here but left uninitialized
@@ -57,7 +113,7 @@ LL | _ => drop(x),
  | if this pattern is matched, `x` is not initialized
 
 error[E0381]: used binding `x` isn't initialized
- --> $DIR/match-cfg-fake-edges.rs:65:16
+ --> $DIR/match-cfg-fake-edges.rs:79:16
  |
 LL | let x;
  | - binding declared here but left uninitialized
@@ -74,7 +130,7 @@ LL | let x = 0;
  | +++
 
 error[E0381]: used binding `x` isn't initialized
- --> $DIR/match-cfg-fake-edges.rs:72:31
+ --> $DIR/match-cfg-fake-edges.rs:86:31
  |
 LL | let x;
  | - binding declared here but left uninitialized
@@ -90,7 +146,7 @@ LL | let x = 0;
  | +++
 
 error[E0382]: use of moved value: `x`
- --> $DIR/match-cfg-fake-edges.rs:85:22
+ --> $DIR/match-cfg-fake-edges.rs:99:22
  |
 LL | let x = String::new();
  | - move occurs because `x` has type `String`, which does not implement the `Copy` trait
@@ -107,7 +163,7 @@ LL | false if { drop(x.clone()); true } => {},
  | ++++++++
 
 error[E0382]: use of moved value: `x`
- --> $DIR/match-cfg-fake-edges.rs:100:22
+ --> $DIR/match-cfg-fake-edges.rs:114:22
  |
 LL | let x = String::new();
  | - move occurs because `x` has type `String`, which does not implement the `Copy` trait
@@ -122,7 +178,7 @@ help: consider cloning the value if the performance cost is acceptable
 LL | false if let Some(()) = { drop(x.clone()); Some(()) } => {},
  | ++++++++
 
-error: aborting due to 8 previous errors
+error: aborting due to 11 previous errors; 1 warning emitted
 
 Some errors have detailed explanations: E0381, E0382.
 For more information about an error, try `rustc --explain E0381`.