Implement arbitrary_enum_discriminant

11 files changed, 164 insertions, 14 deletions

diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs
new file mode 100644
index 00000000000..4da7b5ab24b
--- /dev/null
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.rs
@@ -0,0 +1,9 @@
+#![crate_type="lib"]
+#![feature(arbitrary_enum_discriminant)]
+
+enum Enum {
+//~^ ERROR `#[repr(inttype)]` must be specified
+  Unit = 1,
+  Tuple() = 2,
+  Struct{} = 3,
+}
diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr
new file mode 100644
index 00000000000..2db5372da0c
--- /dev/null
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant-no-repr.stderr
@@ -0,0 +1,14 @@
+error[E0732]: `#[repr(inttype)]` must be specified
+  --> $DIR/arbitrary_enum_discriminant-no-repr.rs:4:1
+   |
+LL | / enum Enum {
+LL | |
+LL | |   Unit = 1,
+LL | |   Tuple() = 2,
+LL | |   Struct{} = 3,
+LL | | }
+   | |_^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0732`.
diff --git a/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs
new file mode 100644
index 00000000000..f2270602d87
--- /dev/null
+++ b/src/test/ui/enum-discriminant/arbitrary_enum_discriminant.rs
@@ -0,0 +1,56 @@
+// run-pass
+#![feature(arbitrary_enum_discriminant, const_raw_ptr_deref, test)]
+
+extern crate test;
+
+use test::black_box;
+
+#[allow(dead_code)]
+#[repr(u8)]
+enum Enum {
+    Unit = 3,
+    Tuple(u16) = 2,
+    Struct {
+        a: u8,
+        b: u16,
+    } = 1,
+}
+
+impl Enum {
+    const unsafe fn tag(&self) -> u8 {
+        *(self as *const Self as *const u8)
+    }
+}
+
+#[allow(dead_code)]
+#[repr(u8)]
+enum FieldlessEnum {
+    Unit = 3,
+    Tuple() = 2,
+    Struct {} = 1,
+}
+
+fn main() {
+    const UNIT: Enum = Enum::Unit;
+    const TUPLE: Enum = Enum::Tuple(5);
+    const STRUCT: Enum = Enum::Struct{a: 7, b: 11};
+
+    // Ensure discriminants are correct during runtime execution
+    assert_eq!(3, unsafe { black_box(UNIT).tag() });
+    assert_eq!(2, unsafe { black_box(TUPLE).tag() });
+    assert_eq!(1, unsafe { black_box(STRUCT).tag() });
+
+    // Ensure discriminants are correct during CTFE
+    const UNIT_TAG: u8 = unsafe { UNIT.tag() };
+    const TUPLE_TAG: u8 = unsafe { TUPLE.tag() };
+    const STRUCT_TAG: u8 = unsafe { STRUCT.tag() };
+
+    assert_eq!(3, UNIT_TAG);
+    assert_eq!(2, TUPLE_TAG);
+    assert_eq!(1, STRUCT_TAG);
+
+    // Ensure `as` conversions are correct
+    assert_eq!(3, FieldlessEnum::Unit as u8);
+    assert_eq!(2, FieldlessEnum::Tuple() as u8);
+    assert_eq!(1, FieldlessEnum::Struct{} as u8);
+}
diff --git a/src/test/run-pass/discriminant_value-wrapper.rs b/src/test/ui/enum-discriminant/discriminant_value-wrapper.rs
index 1fb0d1edddf..daef2de87a9 100644
--- a/src/test/run-pass/discriminant_value-wrapper.rs
+++ b/src/test/ui/enum-discriminant/discriminant_value-wrapper.rs
@@ -1,3 +1,4 @@
+// run-pass
 use std::mem;
 
 enum ADT {
diff --git a/src/test/run-pass/discriminant_value.rs b/src/test/ui/enum-discriminant/discriminant_value.rs
index 162ab27cdff..b7000015c71 100644
--- a/src/test/run-pass/discriminant_value.rs
+++ b/src/test/ui/enum-discriminant/discriminant_value.rs
@@ -1,5 +1,6 @@
+// run-pass
 #![allow(stable_features)]
-#![feature(core, core_intrinsics)]
+#![feature(arbitrary_enum_discriminant, core, core_intrinsics)]
 
 extern crate core;
 use core::intrinsics::discriminant_value;
@@ -38,6 +39,17 @@ enum NullablePointer {
 
 static CONST : u32 = 0xBEEF;
 
+#[allow(dead_code)]
+#[repr(isize)]
+enum Mixed {
+    Unit = 3,
+    Tuple(u16) = 2,
+    Struct {
+        a: u8,
+        b: u16,
+    } = 1,
+}
+
 pub fn main() {
     unsafe {
 
@@ -64,5 +76,9 @@ pub fn main() {
 
         assert_eq!(discriminant_value(&10), 0);
         assert_eq!(discriminant_value(&"test"), 0);
+
+        assert_eq!(3, discriminant_value(&Mixed::Unit));
+        assert_eq!(2, discriminant_value(&Mixed::Tuple(5)));
+        assert_eq!(1, discriminant_value(&Mixed::Struct{a: 7, b: 11}));
     }
 }
diff --git a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs
new file mode 100644
index 00000000000..3e90af4d36a
--- /dev/null
+++ b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.rs
@@ -0,0 +1,10 @@
+#![crate_type="lib"]
+
+enum Enum {
+  Unit = 1,
+  //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
+  Tuple() = 2,
+  //~^ ERROR discriminants on non-unit variants are experimental
+  Struct{} = 3,
+  //~^ ERROR discriminants on non-unit variants are experimental
+}
diff --git a/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr
new file mode 100644
index 00000000000..f50ed2c184d
--- /dev/null
+++ b/src/test/ui/enum-discriminant/feature-gate-arbitrary_enum_discriminant.stderr
@@ -0,0 +1,36 @@
+error[E0658]: discriminants on non-unit variants are experimental
+  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:6:13
+   |
+LL |   Tuple() = 2,
+   |             ^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/60553
+   = help: add #![feature(arbitrary_enum_discriminant)] to the crate attributes to enable
+
+error[E0658]: discriminants on non-unit variants are experimental
+  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:8:14
+   |
+LL |   Struct{} = 3,
+   |              ^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/60553
+   = help: add #![feature(arbitrary_enum_discriminant)] to the crate attributes to enable
+
+error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
+  --> $DIR/feature-gate-arbitrary_enum_discriminant.rs:4:10
+   |
+LL |   Unit = 1,
+   |          ^ disallowed custom discriminant
+LL |
+LL |   Tuple() = 2,
+   |   ----------- tuple variant defined here
+LL |
+LL |   Struct{} = 3,
+   |   ------------ struct variant defined here
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/60553
+   = help: add #![feature(arbitrary_enum_discriminant)] to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/parser/issue-17383.rs b/src/test/ui/parser/issue-17383.rs
index f95005cd914..7bf0e64f2c0 100644
--- a/src/test/ui/parser/issue-17383.rs
+++ b/src/test/ui/parser/issue-17383.rs
@@ -1,6 +1,6 @@
 enum X {
     A = 3,
-    //~^ ERROR custom discriminant values are not allowed in enums with fields
+    //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
     B(usize)
 }
 
diff --git a/src/test/ui/parser/issue-17383.stderr b/src/test/ui/parser/issue-17383.stderr
index 37abd0ff5e1..486c4055807 100644
--- a/src/test/ui/parser/issue-17383.stderr
+++ b/src/test/ui/parser/issue-17383.stderr
@@ -1,11 +1,15 @@
-error: custom discriminant values are not allowed in enums with fields
+error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
   --> $DIR/issue-17383.rs:2:9
    |
 LL |     A = 3,
-   |         ^ invalid custom discriminant
+   |         ^ disallowed custom discriminant
 LL |
 LL |     B(usize)
-   |     -------- variant with a field defined here
+   |     -------- tuple variant defined here
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/60553
+   = help: add #![feature(arbitrary_enum_discriminant)] to the crate attributes to enable
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/parser/tag-variant-disr-non-nullary.rs b/src/test/ui/parser/tag-variant-disr-non-nullary.rs
index 305edc4ad5a..a9cfdd549c7 100644
--- a/src/test/ui/parser/tag-variant-disr-non-nullary.rs
+++ b/src/test/ui/parser/tag-variant-disr-non-nullary.rs
@@ -1,6 +1,6 @@
 enum Color {
     Red = 0xff0000,
-    //~^ ERROR custom discriminant values are not allowed in enums with fields
+    //~^ ERROR custom discriminant values are not allowed in enums with tuple or struct variants
     Green = 0x00ff00,
     Blue = 0x0000ff,
     Black = 0x000000,
diff --git a/src/test/ui/parser/tag-variant-disr-non-nullary.stderr b/src/test/ui/parser/tag-variant-disr-non-nullary.stderr
index 2d3b2839531..13b46c6e8b3 100644
--- a/src/test/ui/parser/tag-variant-disr-non-nullary.stderr
+++ b/src/test/ui/parser/tag-variant-disr-non-nullary.stderr
@@ -1,21 +1,25 @@
-error: custom discriminant values are not allowed in enums with fields
+error[E0658]: custom discriminant values are not allowed in enums with tuple or struct variants
   --> $DIR/tag-variant-disr-non-nullary.rs:2:11
    |
 LL |     Red = 0xff0000,
-   |           ^^^^^^^^ invalid custom discriminant
+   |           ^^^^^^^^ disallowed custom discriminant
 LL |
 LL |     Green = 0x00ff00,
-   |             ^^^^^^^^ invalid custom discriminant
+   |             ^^^^^^^^ disallowed custom discriminant
 LL |     Blue = 0x0000ff,
-   |            ^^^^^^^^ invalid custom discriminant
+   |            ^^^^^^^^ disallowed custom discriminant
 LL |     Black = 0x000000,
-   |             ^^^^^^^^ invalid custom discriminant
+   |             ^^^^^^^^ disallowed custom discriminant
 LL |     White = 0xffffff,
-   |             ^^^^^^^^ invalid custom discriminant
+   |             ^^^^^^^^ disallowed custom discriminant
 LL |     Other(usize),
-   |     ------------ variant with a field defined here
+   |     ------------ tuple variant defined here
 LL |     Other2(usize, usize),
-   |     -------------------- variant with fields defined here
+   |     -------------------- tuple variant defined here
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/60553
+   = help: add #![feature(arbitrary_enum_discriminant)] to the crate attributes to enable
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0658`.