Also test for undef in enum discriminant

The error message is sub-par, but fixing that requries moving ScalarMaybeUndef
to librustc which would conflict badly with another PR that is in flight.

diff --git a/src/test/ui/consts/const-eval/ub-enum.rs b/src/test/ui/consts/const-eval/ub-enum.rs
index 7b6527464c5483ec5303cf16800478fdd1ff63ff..309627581d0512cd5a881ceb013b7f03cdb7d306 100644 (file)
--- a/src/test/ui/consts/const-eval/ub-enum.rs
+++ b/src/test/ui/consts/const-eval/ub-enum.rs
@@ -33,10 +33,15 @@ enum Enum2 {
 union TransmuteEnum2 {
     a: usize,
     b: Enum2,
+    c: (),
 }
 const BAD_ENUM2 : Enum2 = unsafe { TransmuteEnum2 { a: 0 }.b };
 //~^ ERROR is undefined behavior
 
+// Undef enum discriminant. In an arry to avoid `Scalar` layout.
+const BAD_ENUM3 : [Enum2; 2] = [unsafe { TransmuteEnum2 { c: () }.b }; 2];
+//~^ ERROR is undefined behavior
+
 // Invalid enum field content (mostly to test printing of apths for enum tuple
 // variants and tuples).
 union TransmuteChar {

diff --git a/src/test/ui/consts/const-eval/ub-enum.stderr b/src/test/ui/consts/const-eval/ub-enum.stderr
index 4ba30f1a9911af1a2698aedadac3568ff9ae23c8..57c41711536d9485749b501a0f5cf85d87258306 100644 (file)
--- a/src/test/ui/consts/const-eval/ub-enum.stderr
+++ b/src/test/ui/consts/const-eval/ub-enum.stderr
@@ -7,7 +7,7 @@ LL | const BAD_ENUM: Enum = unsafe { TransmuteEnum { a: &1 }.b };
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-enum.rs:37:1
+  --> $DIR/ub-enum.rs:38:1
    |
 LL | const BAD_ENUM2 : Enum2 = unsafe { TransmuteEnum2 { a: 0 }.b };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 0, but expected a valid enum discriminant
@@ -15,13 +15,21 @@ LL | const BAD_ENUM2 : Enum2 = unsafe { TransmuteEnum2 { a: 0 }.b };
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
 
 error[E0080]: it is undefined behavior to use this value
-  --> $DIR/ub-enum.rs:47:1
+  --> $DIR/ub-enum.rs:42:1
+   |
+LL | const BAD_ENUM3 : [Enum2; 2] = [unsafe { TransmuteEnum2 { c: () }.b }; 2];
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempted to read undefined bytes
+   |
+   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
+
+error[E0080]: it is undefined behavior to use this value
+  --> $DIR/ub-enum.rs:52:1
    |
 LL | const BAD_ENUM_CHAR : Option<(char, char)> = Some(('x', unsafe { TransmuteChar { a: !0 }.b }));
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered 4294967295 at .Some.0.1, but expected something in the range 0..=1114111
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0080`.