add some more repr(C) enum size tests

Author: RalfJung

tests/auxiliary/minicore.rs

@@ -162,6 +162,29 @@ macro_rules! stringify {
     };
 }
 
+#[lang = "neg"]
+pub trait Neg {
+    type Output;
+
+    fn neg(self) -> Self::Output;
+}
+
+impl Neg for i32 {
+    type Output = i32;
+
+    fn neg(self) -> i32 {
+        loop {} // Dummy impl, not actually used
+    }
+}
+
+impl Neg for isize {
+    type Output = isize;
+
+    fn neg(self) -> isize {
+        loop {} // Dummy impl, not actually used
+    }
+}
+
 #[lang = "add"]
 pub trait Add<Rhs = Self> {
     type Output;

tests/ui/enum-discriminant/repr-c-size.linux32.stderr

@@ -11,5 +11,18 @@ note: the lint level is defined here
 LL | #[warn(overflowing_literals)]
    |        ^^^^^^^^^^^^^^^^^^^^
 
-warning: 1 warning emitted
+warning: literal out of range for `isize`
+  --> $DIR/repr-c-size.rs:43:9
+   |
+LL |     A = 4294967294, // u32::MAX - 1
+   |         ^^^^^^^^^^
+   |
+   = note: the literal `4294967294` does not fit into the type `isize` whose range is `-2147483648..=2147483647`
+note: the lint level is defined here
+  --> $DIR/repr-c-size.rs:41:8
+   |
+LL | #[warn(overflowing_literals)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+
+warning: 2 warnings emitted
 

tests/ui/enum-discriminant/repr-c-size.msvc32.stderr

@@ -12,5 +12,19 @@ note: the lint level is defined here
 LL | #[warn(overflowing_literals)]
    |        ^^^^^^^^^^^^^^^^^^^^
 
-warning: 1 warning emitted
+warning: literal out of range for `i32`
+  --> $DIR/repr-c-size.rs:43:9
+   |
+LL |     A = 4294967294, // u32::MAX - 1
+   |         ^^^^^^^^^^
+   |
+   = note: the literal `4294967294` does not fit into the type `i32` whose range is `-2147483648..=2147483647`
+   = help: consider using the type `u32` instead
+note: the lint level is defined here
+  --> $DIR/repr-c-size.rs:41:8
+   |
+LL | #[warn(overflowing_literals)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+
+warning: 2 warnings emitted
 

tests/ui/enum-discriminant/repr-c-size.msvc64.stderr

@@ -12,5 +12,19 @@ note: the lint level is defined here
 LL | #[warn(overflowing_literals)]
    |        ^^^^^^^^^^^^^^^^^^^^
 
-warning: 1 warning emitted
+warning: literal out of range for `i32`
+  --> $DIR/repr-c-size.rs:43:9
+   |
+LL |     A = 4294967294, // u32::MAX - 1
+   |         ^^^^^^^^^^
+   |
+   = note: the literal `4294967294` does not fit into the type `i32` whose range is `-2147483648..=2147483647`
+   = help: consider using the type `u32` instead
+note: the lint level is defined here
+  --> $DIR/repr-c-size.rs:41:8
+   |
+LL | #[warn(overflowing_literals)]
+   |        ^^^^^^^^^^^^^^^^^^^^
+
+warning: 2 warnings emitted
 

tests/ui/enum-discriminant/repr-c-size.rs

@@ -34,4 +34,46 @@ const _: () = if mem::size_of::<OverflowingEnum>() != 8 {
     unsafe { hint::unreachable() }
 };
 
+// Each value fits in i32 or u32, but not all values fit into the same type.
+// C compiler demo: <https://godbolt.org/z/GPYafPhjK>
+// FIXME: This seems to do the wrong thing for 32bit Linux?
+#[repr(C)]
+#[warn(overflowing_literals)]
+enum OverflowingEnum2 {
+    A = 4294967294, // u32::MAX - 1
+    //[linux32,msvc32,msvc64]~^ WARN: literal out of range
+    B = -1,
+}
+
+#[cfg(not(linux64))]
+const _: () = if mem::size_of::<OverflowingEnum2>() != 4 {
+    unsafe { hint::unreachable() }
+};
+#[cfg(linux64)]
+const _: () = if mem::size_of::<OverflowingEnum2>() != 8 {
+    unsafe { hint::unreachable() }
+};
+
+// Force i32 or u32, respectively.
+// C compiler demo: <https://godbolt.org/z/bGss855a4>
+#[repr(C)]
+enum I32Enum {
+    A = 2147483647, // i32::MAX
+    B = -2147483647,
+}
+const _: () = if mem::size_of::<I32Enum>() != 4 {
+    unsafe { hint::unreachable() }
+};
+
+// C compiler demo: <https://godbolt.org/z/MeE9YGj4n>
+#[repr(C)]
+#[allow(overflowing_literals)]
+enum U32Enum {
+    A = 4294967295, // u32::MAX
+    B = 0,
+}
+const _: () = if mem::size_of::<U32Enum>() != 4 {
+    unsafe { hint::unreachable() }
+};
+
 fn main() {}