Visit patterns in THIR let expressions

This fixes some THIR unsafety checking errors not being emitted for
let expressions in these situations.

3 files changed, 45 insertions, 27 deletions

diff --git a/tests/ui/union/union-unsafe.mir.stderr b/tests/ui/union/union-unsafe.mir.stderr
index 544213dbc55..15f059ffa48 100644
--- a/tests/ui/union/union-unsafe.mir.stderr
+++ b/tests/ui/union/union-unsafe.mir.stderr
@@ -1,5 +1,5 @@
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:33:5
+  --> $DIR/union-unsafe.rs:34:5
    |
 LL |     *(u.p) = 13;
    |     ^^^^^^^^^^^ access to union field
@@ -7,7 +7,7 @@ LL |     *(u.p) = 13;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:46:6
+  --> $DIR/union-unsafe.rs:47:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -15,7 +15,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:52:6
+  --> $DIR/union-unsafe.rs:53:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -23,7 +23,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:60:13
+  --> $DIR/union-unsafe.rs:61:13
    |
 LL |     let a = u1.a;
    |             ^^^^ access to union field
@@ -31,7 +31,7 @@ LL |     let a = u1.a;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:63:14
+  --> $DIR/union-unsafe.rs:64:14
    |
 LL |     let U1 { a } = u1;
    |              ^ access to union field
@@ -39,7 +39,7 @@ LL |     let U1 { a } = u1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:64:12
+  --> $DIR/union-unsafe.rs:65:12
    |
 LL |     if let U1 { a: 12 } = u1 {}
    |            ^^^^^^^^^^^^ access to union field
@@ -47,7 +47,15 @@ LL |     if let U1 { a: 12 } = u1 {}
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:69:6
+  --> $DIR/union-unsafe.rs:66:12
+   |
+LL |     if let Some(U1 { a: 13 }) = Some(u1) {}
+   |            ^^^^^^^^^^^^^^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-unsafe.rs:71:6
    |
 LL |     *u2.a = String::from("new");
    |      ^^^^ access to union field
@@ -55,7 +63,7 @@ LL |     *u2.a = String::from("new");
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:73:6
+  --> $DIR/union-unsafe.rs:75:6
    |
 LL |     *u3.a = 1;
    |      ^^^^ access to union field
@@ -63,13 +71,13 @@ LL |     *u3.a = 1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:77:6
+  --> $DIR/union-unsafe.rs:79:6
    |
 LL |     *u3.a = String::from("new");
    |      ^^^^ access to union field
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors
 
 For more information about this error, try `rustc --explain E0133`.
diff --git a/tests/ui/union/union-unsafe.rs b/tests/ui/union/union-unsafe.rs
index 5e1837a901d..d1465486f77 100644
--- a/tests/ui/union/union-unsafe.rs
+++ b/tests/ui/union/union-unsafe.rs
@@ -1,30 +1,31 @@
 // revisions: mir thir
 // [thir]compile-flags: -Z thir-unsafeck
 
-use std::mem::ManuallyDrop;
 use std::cell::RefCell;
+use std::mem::ManuallyDrop;
 
 union U1 {
-    a: u8
+    a: u8,
 }
 
 union U2 {
-    a: ManuallyDrop<String>
+    a: ManuallyDrop<String>,
 }
 
 union U3<T> {
-    a: ManuallyDrop<T>
+    a: ManuallyDrop<T>,
 }
 
 union U4<T: Copy> {
-    a: T
+    a: T,
 }
 
 union URef {
     p: &'static mut i32,
 }
 
-union URefCell { // field that does not drop but is not `Copy`, either
+union URefCell {
+    // field that does not drop but is not `Copy`, either
     a: (ManuallyDrop<RefCell<i32>>, i32),
 }
 
@@ -62,6 +63,7 @@ fn main() {
 
     let U1 { a } = u1; //~ ERROR access to union field is unsafe
     if let U1 { a: 12 } = u1 {} //~ ERROR access to union field is unsafe
+    if let Some(U1 { a: 13 }) = Some(u1) {} //~ ERROR access to union field is unsafe
     // let U1 { .. } = u1; // OK
 
     let mut u2 = U2 { a: ManuallyDrop::new(String::from("old")) }; // OK
diff --git a/tests/ui/union/union-unsafe.thir.stderr b/tests/ui/union/union-unsafe.thir.stderr
index f959fe5bdb5..9ce835497c5 100644
--- a/tests/ui/union/union-unsafe.thir.stderr
+++ b/tests/ui/union/union-unsafe.thir.stderr
@@ -1,5 +1,5 @@
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:33:6
+  --> $DIR/union-unsafe.rs:34:6
    |
 LL |     *(u.p) = 13;
    |      ^^^^^ access to union field
@@ -7,7 +7,7 @@ LL |     *(u.p) = 13;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:46:6
+  --> $DIR/union-unsafe.rs:47:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -15,7 +15,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:52:6
+  --> $DIR/union-unsafe.rs:53:6
    |
 LL |     *u3.a = T::default();
    |      ^^^^ access to union field
@@ -23,7 +23,7 @@ LL |     *u3.a = T::default();
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:60:13
+  --> $DIR/union-unsafe.rs:61:13
    |
 LL |     let a = u1.a;
    |             ^^^^ access to union field
@@ -31,7 +31,7 @@ LL |     let a = u1.a;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:63:14
+  --> $DIR/union-unsafe.rs:64:14
    |
 LL |     let U1 { a } = u1;
    |              ^ access to union field
@@ -39,15 +39,23 @@ LL |     let U1 { a } = u1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:64:8
+  --> $DIR/union-unsafe.rs:65:20
    |
 LL |     if let U1 { a: 12 } = u1 {}
-   |        ^^^^^^^^^^^^^^^^^^^^^ access to union field
+   |                    ^^ access to union field
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:69:6
+  --> $DIR/union-unsafe.rs:66:25
+   |
+LL |     if let Some(U1 { a: 13 }) = Some(u1) {}
+   |                         ^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-unsafe.rs:71:6
    |
 LL |     *u2.a = String::from("new");
    |      ^^^^ access to union field
@@ -55,7 +63,7 @@ LL |     *u2.a = String::from("new");
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:73:6
+  --> $DIR/union-unsafe.rs:75:6
    |
 LL |     *u3.a = 1;
    |      ^^^^ access to union field
@@ -63,13 +71,13 @@ LL |     *u3.a = 1;
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
 error[E0133]: access to union field is unsafe and requires unsafe function or block
-  --> $DIR/union-unsafe.rs:77:6
+  --> $DIR/union-unsafe.rs:79:6
    |
 LL |     *u3.a = String::from("new");
    |      ^^^^ access to union field
    |
    = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
 
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors
 
 For more information about this error, try `rustc --explain E0133`.