Rollup merge of #87734 - Smittyvb:more-union-tests, r=LeSeulArtichaut

Test dropping union fields more

Now that #87403 is merged, a few more tests can be added for reads/writes to dropping union fields.

r? ``@LeSeulArtichaut``

Author: JohnTitor

src/test/ui/union/union-drop.rs

@@ -1,4 +1,7 @@
 // run-pass
+// revisions: mirunsafeck thirunsafeck
+// [thirunsafeck]compile-flags: -Z thir-unsafeck
+
 #![allow(dead_code)]
 #![allow(unused_variables)]
 

src/test/ui/union/union-drop.thirunsafeck.stderr

@@ -0,0 +1,59 @@
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:20:5
+   |
+LL |     foo.a += 5;
+   |     ^^^^^^^^^^ 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-assignop.rs:21:5
+   |
+LL |     foo.b += Dropping;
+   |     ^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: assignment to union field that might need dropping is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:22:5
+   |
+LL |     foo.b = Dropping;
+   |     ^^^^^^^^^^^^^^^^ assignment to union field that might need dropping
+   |
+   = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:23:5
+   |
+LL |     foo.a;
+   |     ^^^^^ 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-assignop.rs:25:5
+   |
+LL |     foo.b;
+   |     ^^^^^ 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-assignop.rs:27:13
+   |
+LL |     foo.b = foo.b;
+   |             ^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: assignment to union field that might need dropping is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:27:5
+   |
+LL |     foo.b = foo.b;
+   |     ^^^^^^^^^^^^^ assignment to union field that might need dropping
+   |
+   = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0133`.

src/test/ui/unsafe/union-assignop.mirunsafeck.stderr

@@ -0,0 +1,30 @@
+// revisions: mirunsafeck thirunsafeck
+// [thirunsafeck]compile-flags: -Z thir-unsafeck
+
+#![feature(untagged_unions)]
+
+use std::ops::AddAssign;
+
+struct Dropping;
+impl AddAssign for Dropping {
+    fn add_assign(&mut self, _: Self) {}
+}
+
+union Foo {
+    a: u8, // non-dropping
+    b: Dropping, // treated as dropping
+}
+
+fn main() {
+    let mut foo = Foo { a: 42 };
+    foo.a += 5; //~ ERROR access to union field is unsafe
+    foo.b += Dropping; //~ ERROR access to union field is unsafe
+    foo.b = Dropping; //~ ERROR assignment to union field that might need dropping is unsafe
+    foo.a; //~ ERROR access to union field is unsafe
+    let foo = Foo { a: 42 };
+    foo.b; //~ ERROR access to union field is unsafe
+    let mut foo = Foo { a: 42 };
+    foo.b = foo.b;
+    //~^ ERROR access to union field is unsafe
+    //~| ERROR assignment to union field that might need dropping
+}

src/test/ui/unsafe/union-assignop.rs

@@ -0,0 +1,59 @@
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:20:5
+   |
+LL |     foo.a += 5;
+   |     ^^^^^ 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-assignop.rs:21:5
+   |
+LL |     foo.b += Dropping;
+   |     ^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: assignment to union field that might need dropping is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:22:5
+   |
+LL |     foo.b = Dropping;
+   |     ^^^^^^^^^^^^^^^^ assignment to union field that might need dropping
+   |
+   = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:23:5
+   |
+LL |     foo.a;
+   |     ^^^^^ 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-assignop.rs:25:5
+   |
+LL |     foo.b;
+   |     ^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error[E0133]: assignment to union field that might need dropping is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:27:5
+   |
+LL |     foo.b = foo.b;
+   |     ^^^^^^^^^^^^^ assignment to union field that might need dropping
+   |
+   = note: the previous content of the field will be dropped, which causes undefined behavior if the field was not properly initialized
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/union-assignop.rs:27:13
+   |
+LL |     foo.b = foo.b;
+   |             ^^^^^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0133`.