Add/extend tests for offset_of! for enums with uninhabited variants

Author: zachs18

tests/ui/offset-of/offset-of-enum-valid.rs

@@ -0,0 +1,61 @@
+//@ run-pass
+#![feature(offset_of_enum)]
+#![allow(unused)]
+
+use std::mem::offset_of;
+
+enum Never {}
+
+#[repr(align(2))]
+struct AlignedNever(Never);
+
+enum Alpha {
+    One(u8),
+    Two(u8),
+    Three(u8, u8, Never),
+}
+
+enum Beta {
+    One(u8),
+    Two(u8, Never),
+}
+
+enum Gamma {
+    One(u32),
+    Two(u8, u8, u8, Never),
+}
+
+enum Delta {
+    One(u8, Never),
+    Two(u8, u8, Never),
+}
+
+fn main() {
+    assert!(offset_of!(Alpha, One.0) <= size_of::<Alpha>() - size_of::<u8>());
+    assert!(offset_of!(Alpha, Two.0) <= size_of::<Alpha>() - size_of::<u8>());
+    assert!(offset_of!(Alpha, Three.0) <= size_of::<Alpha>() - size_of::<u8>());
+    assert!(offset_of!(Alpha, Three.1) <= size_of::<Alpha>() - size_of::<u8>());
+    assert!(offset_of!(Alpha, Three.2) <= size_of::<Alpha>() - size_of::<Never>());
+    assert!(offset_of!(Alpha, Three.0) != offset_of!(Alpha, Three.1));
+
+    assert!(offset_of!(Beta, One.0) <= size_of::<Beta>() - size_of::<u8>());
+    assert!(offset_of!(Beta, Two.0) <= size_of::<Beta>() - size_of::<u8>());
+    assert!(offset_of!(Beta, Two.1) <= size_of::<Beta>() - size_of::<Never>());
+
+    assert!(offset_of!(Gamma, One.0) <= size_of::<Gamma>() - size_of::<u32>());
+    assert!(offset_of!(Gamma, Two.0) <= size_of::<Gamma>() - size_of::<u8>());
+    assert!(offset_of!(Gamma, Two.1) <= size_of::<Gamma>() - size_of::<u8>());
+    assert!(offset_of!(Gamma, Two.2) <= size_of::<Gamma>() - size_of::<u8>());
+    assert!(offset_of!(Gamma, Two.3) <= size_of::<Gamma>() - size_of::<Never>());
+    assert!(offset_of!(Gamma, Two.0) != offset_of!(Gamma, Two.1));
+    assert!(offset_of!(Gamma, Two.0) != offset_of!(Gamma, Two.2));
+    assert!(offset_of!(Gamma, Two.1) != offset_of!(Gamma, Two.2));
+
+    assert!(offset_of!(Delta, One.0) <= size_of::<Delta>() - size_of::<u8>());
+    assert!(offset_of!(Delta, One.1) <= size_of::<Delta>() - size_of::<Never>());
+    assert!(offset_of!(Delta, Two.0) <= size_of::<Delta>() - size_of::<u8>());
+    assert!(offset_of!(Delta, Two.0) <= size_of::<Delta>() - size_of::<u8>());
+    assert!(offset_of!(Delta, Two.1) <= size_of::<Delta>() - size_of::<u8>());
+    assert!(offset_of!(Delta, Two.2) <= size_of::<Delta>() - size_of::<Never>());
+    assert!(offset_of!(Delta, Two.0) != offset_of!(Delta, Two.1));
+}

tests/ui/offset-of/offset-of-enum.rs

@@ -2,9 +2,12 @@
 
 use std::mem::offset_of;
 
+enum Never {}
+
 enum Alpha {
     One(u8),
     Two(u8),
+    Three(u8, u8, Never),
 }
 
 fn main() {
@@ -15,4 +18,8 @@ fn main() {
     offset_of!(Alpha, Two.foo); //~ ERROR no field named `foo` on enum variant `Alpha::Two`
     offset_of!(Alpha, NonExistent); //~ ERROR no variant named `NonExistent` found for enum `Alpha`
     offset_of!(Beta, One); //~ ERROR cannot find type `Beta` in this scope
+    offset_of!(Alpha, Three.0);
+    offset_of!(Alpha, Three.1);
+    offset_of!(Alpha, Three.2);
+    offset_of!(Alpha, Three.2.NonExistent); //~ ERROR no variant named `NonExistent` found for enum `Never`
 }

tests/ui/offset-of/offset-of-enum.stderr

@@ -1,5 +1,5 @@
 error[E0573]: expected type, found variant `Alpha::One`
-  --> $DIR/offset-of-enum.rs:11:16
+  --> $DIR/offset-of-enum.rs:14:16
    |
 LL |     offset_of!(Alpha::One, 0);
    |                ^^^^^^^^^^
@@ -8,40 +8,46 @@ LL |     offset_of!(Alpha::One, 0);
    |                help: try using the variant's enum: `Alpha`
 
 error[E0412]: cannot find type `Beta` in this scope
-  --> $DIR/offset-of-enum.rs:17:16
+  --> $DIR/offset-of-enum.rs:20:16
    |
 LL |     offset_of!(Beta, One);
    |                ^^^^ not found in this scope
 
 error[E0795]: `One` is an enum variant; expected field at end of `offset_of`
-  --> $DIR/offset-of-enum.rs:12:23
+  --> $DIR/offset-of-enum.rs:15:23
    |
 LL |     offset_of!(Alpha, One);
    |                       ^^^ enum variant
 
 error[E0609]: no field named `1` on enum variant `Alpha::Two`
-  --> $DIR/offset-of-enum.rs:14:23
+  --> $DIR/offset-of-enum.rs:17:23
    |
 LL |     offset_of!(Alpha, Two.1);
    |                       ^^^ - ...does not have this field
    |                       |
    |                       this enum variant...
 
 error[E0609]: no field named `foo` on enum variant `Alpha::Two`
-  --> $DIR/offset-of-enum.rs:15:23
+  --> $DIR/offset-of-enum.rs:18:23
    |
 LL |     offset_of!(Alpha, Two.foo);
    |                       ^^^ --- ...does not have this field
    |                       |
    |                       this enum variant...
 
 error[E0599]: no variant named `NonExistent` found for enum `Alpha`
-  --> $DIR/offset-of-enum.rs:16:23
+  --> $DIR/offset-of-enum.rs:19:23
    |
 LL |     offset_of!(Alpha, NonExistent);
    |                       ^^^^^^^^^^^ variant not found
 
-error: aborting due to 6 previous errors
+error[E0599]: no variant named `NonExistent` found for enum `Never`
+  --> $DIR/offset-of-enum.rs:24:31
+   |
+LL |     offset_of!(Alpha, Three.2.NonExistent);
+   |                               ^^^^^^^^^^^ variant not found
+
+error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0412, E0573, E0599, E0609, E0795.
 For more information about an error, try `rustc --explain E0412`.