Test the borrowck behavior of if-let guards

6 files changed, 90 insertions, 11 deletions

diff --git a/src/test/ui/borrowck/borrowck-drop-from-guard.rs b/src/test/ui/borrowck/borrowck-drop-from-guard.rs
index 4995029a70f..0f320af2657 100644
--- a/src/test/ui/borrowck/borrowck-drop-from-guard.rs
+++ b/src/test/ui/borrowck/borrowck-drop-from-guard.rs
@@ -1,3 +1,5 @@
+#![feature(if_let_guard)]
+
 fn foo(_:String) {}
 
 fn main()
@@ -8,4 +10,11 @@ fn main()
         Some(_) => {}
         None => { foo(my_str); } //~ ERROR [E0382]
     }
+
+    let my_str = "hello".to_owned();
+    match Some(42) {
+        Some(_) if let Some(()) = { drop(my_str); None } => {}
+        Some(_) => {}
+        None => { foo(my_str); } //~ ERROR [E0382]
+    }
 }
diff --git a/src/test/ui/borrowck/borrowck-drop-from-guard.stderr b/src/test/ui/borrowck/borrowck-drop-from-guard.stderr
index eaf4bb38bc5..9fa28efd855 100644
--- a/src/test/ui/borrowck/borrowck-drop-from-guard.stderr
+++ b/src/test/ui/borrowck/borrowck-drop-from-guard.stderr
@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `my_str`
-  --> $DIR/borrowck-drop-from-guard.rs:9:23
+  --> $DIR/borrowck-drop-from-guard.rs:11:23
    |
 LL |     let my_str = "hello".to_owned();
    |         ------ move occurs because `my_str` has type `String`, which does not implement the `Copy` trait
@@ -15,6 +15,23 @@ help: consider cloning the value if the performance cost is acceptable
 LL |         Some(_) if { drop(my_str.clone()); false } => {}
    |                                 ++++++++
 
-error: aborting due to previous error
+error[E0382]: use of moved value: `my_str`
+  --> $DIR/borrowck-drop-from-guard.rs:18:23
+   |
+LL |     let my_str = "hello".to_owned();
+   |         ------ move occurs because `my_str` has type `String`, which does not implement the `Copy` trait
+LL |     match Some(42) {
+LL |         Some(_) if let Some(()) = { drop(my_str); None } => {}
+   |                                          ------ value moved here
+LL |         Some(_) => {}
+LL |         None => { foo(my_str); }
+   |                       ^^^^^^ value used here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |         Some(_) if let Some(()) = { drop(my_str.clone()); None } => {}
+   |                                                ++++++++
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0382`.
diff --git a/src/test/ui/borrowck/borrowck-mutate-in-guard.rs b/src/test/ui/borrowck/borrowck-mutate-in-guard.rs
index 9cbceeb945c..d80a9e81576 100644
--- a/src/test/ui/borrowck/borrowck-mutate-in-guard.rs
+++ b/src/test/ui/borrowck/borrowck-mutate-in-guard.rs
@@ -1,9 +1,11 @@
+#![feature(if_let_guard)]
+
 enum Enum<'a> {
     A(&'a isize),
     B(bool),
 }
 
-fn foo() -> isize {
+fn if_guard() -> isize {
     let mut n = 42;
     let mut x = Enum::A(&mut n);
     match x {
@@ -16,6 +18,17 @@ fn foo() -> isize {
     }
 }
 
-fn main() {
-    foo();
+fn if_let_guard() -> isize {
+    let mut n = 42;
+    let mut x = Enum::A(&mut n);
+    match x {
+        Enum::A(_) if let Some(()) = { x = Enum::B(false); None } => 1,
+        //~^ ERROR cannot assign `x` in match guard
+        Enum::A(_) if let Some(()) = { let y = &mut x; *y = Enum::B(false); None } => 1,
+        //~^ ERROR cannot mutably borrow `x` in match guard
+        Enum::A(p) => *p,
+        Enum::B(_) => 2,
+    }
 }
+
+fn main() {}
diff --git a/src/test/ui/borrowck/borrowck-mutate-in-guard.stderr b/src/test/ui/borrowck/borrowck-mutate-in-guard.stderr
index 6d05e97252d..dbb3272fdc3 100644
--- a/src/test/ui/borrowck/borrowck-mutate-in-guard.stderr
+++ b/src/test/ui/borrowck/borrowck-mutate-in-guard.stderr
@@ -1,5 +1,5 @@
 error[E0510]: cannot assign `x` in match guard
-  --> $DIR/borrowck-mutate-in-guard.rs:10:25
+  --> $DIR/borrowck-mutate-in-guard.rs:12:25
    |
 LL |     match x {
    |           - value is immutable in match guard
@@ -7,7 +7,7 @@ LL |         Enum::A(_) if { x = Enum::B(false); false } => 1,
    |                         ^^^^^^^^^^^^^^^^^^ cannot assign
 
 error[E0510]: cannot mutably borrow `x` in match guard
-  --> $DIR/borrowck-mutate-in-guard.rs:12:33
+  --> $DIR/borrowck-mutate-in-guard.rs:14:33
    |
 LL |     match x {
    |           - value is immutable in match guard
@@ -15,6 +15,23 @@ LL |     match x {
 LL |         Enum::A(_) if { let y = &mut x; *y = Enum::B(false); false } => 1,
    |                                 ^^^^^^ cannot mutably borrow
 
-error: aborting due to 2 previous errors
+error[E0510]: cannot assign `x` in match guard
+  --> $DIR/borrowck-mutate-in-guard.rs:25:40
+   |
+LL |     match x {
+   |           - value is immutable in match guard
+LL |         Enum::A(_) if let Some(()) = { x = Enum::B(false); None } => 1,
+   |                                        ^^^^^^^^^^^^^^^^^^ cannot assign
+
+error[E0510]: cannot mutably borrow `x` in match guard
+  --> $DIR/borrowck-mutate-in-guard.rs:27:48
+   |
+LL |     match x {
+   |           - value is immutable in match guard
+...
+LL |         Enum::A(_) if let Some(()) = { let y = &mut x; *y = Enum::B(false); None } => 1,
+   |                                                ^^^^^^ cannot mutably borrow
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0510`.
diff --git a/src/test/ui/borrowck/issue-31287-drop-in-guard.rs b/src/test/ui/borrowck/issue-31287-drop-in-guard.rs
index 07125b98a1f..5b824adc6e2 100644
--- a/src/test/ui/borrowck/issue-31287-drop-in-guard.rs
+++ b/src/test/ui/borrowck/issue-31287-drop-in-guard.rs
@@ -1,8 +1,15 @@
+#![feature(if_let_guard)]
+
 fn main() {
     let a = Some("...".to_owned());
     let b = match a {
         Some(_) if { drop(a); false } => None,
         x => x, //~ ERROR use of moved value: `a`
     };
-    println!("{:?}", b);
+
+    let a = Some("...".to_owned());
+    let b = match a {
+        Some(_) if let Some(()) = { drop(a); None } => None,
+        x => x, //~ ERROR use of moved value: `a`
+    };
 }
diff --git a/src/test/ui/borrowck/issue-31287-drop-in-guard.stderr b/src/test/ui/borrowck/issue-31287-drop-in-guard.stderr
index ad898fcabd9..18f371c2073 100644
--- a/src/test/ui/borrowck/issue-31287-drop-in-guard.stderr
+++ b/src/test/ui/borrowck/issue-31287-drop-in-guard.stderr
@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `a`
-  --> $DIR/issue-31287-drop-in-guard.rs:5:9
+  --> $DIR/issue-31287-drop-in-guard.rs:7:9
    |
 LL |     let a = Some("...".to_owned());
    |         - move occurs because `a` has type `Option<String>`, which does not implement the `Copy` trait
@@ -14,6 +14,22 @@ help: consider cloning the value if the performance cost is acceptable
 LL |         Some(_) if { drop(a.clone()); false } => None,
    |                            ++++++++
 
-error: aborting due to previous error
+error[E0382]: use of moved value: `a`
+  --> $DIR/issue-31287-drop-in-guard.rs:13:9
+   |
+LL |     let a = Some("...".to_owned());
+   |         - move occurs because `a` has type `Option<String>`, which does not implement the `Copy` trait
+LL |     let b = match a {
+LL |         Some(_) if let Some(()) = { drop(a); None } => None,
+   |                                          - value moved here
+LL |         x => x,
+   |         ^ value used here after move
+   |
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |         Some(_) if let Some(()) = { drop(a.clone()); None } => None,
+   |                                           ++++++++
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0382`.