more erroneous-const tests

Author: RalfJung

src/test/ui/consts/const-eval/erroneous-const.rs

@@ -10,6 +10,8 @@ impl<T> PrintName<T> {
 
 const fn no_codegen<T>() {
     if false {
+        // This bad constant is only used in dead code in a no-codegen function... and yet we still
+        // must make sure that the build fails.
         let _ = PrintName::<T>::VOID; //~ERROR could not evaluate static initializer
     }
 }

src/test/ui/consts/const-eval/erroneous-const.stderr

@@ -27,16 +27,16 @@ LL | #![warn(const_err, unconditional_panic)]
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
 error[E0080]: could not evaluate static initializer
-  --> $DIR/erroneous-const.rs:13:17
+  --> $DIR/erroneous-const.rs:15:17
    |
 LL |         let _ = PrintName::<T>::VOID;
    |                 ^^^^^^^^^^^^^^^^^^^^
    |                 |
    |                 referenced constant has errors
-   |                 inside `no_codegen::<i32>` at $DIR/erroneous-const.rs:13:17
+   |                 inside `no_codegen::<i32>` at $DIR/erroneous-const.rs:15:17
 ...
 LL | pub static FOO: () = no_codegen::<i32>();
-   |                      ------------------- inside `FOO` at $DIR/erroneous-const.rs:17:22
+   |                      ------------------- inside `FOO` at $DIR/erroneous-const.rs:19:22
 
 error: aborting due to previous error; 2 warnings emitted
 

src/test/ui/consts/const-eval/erroneous-const2.rs

@@ -0,0 +1,21 @@
+//! Make sure we error on erroneous consts even if they are unused.
+#![warn(const_err, unconditional_panic)]
+
+struct PrintName<T>(T);
+impl<T> PrintName<T> {
+    const VOID: () = [()][2]; //~WARN any use of this value will cause an error
+    //~^ WARN this operation will panic at runtime
+    //~| WARN this was previously accepted by the compiler but is being phased out
+}
+
+pub static FOO: () = {
+    if false {
+        // This bad constant is only used in dead code in a static initializer... and yet we still
+        // must make sure that the build fails.
+        let _ = PrintName::<i32>::VOID; //~ERROR could not evaluate static initializer
+    }
+};
+
+fn main() {
+    FOO
+}

src/test/ui/consts/const-eval/erroneous-const2.stderr

@@ -0,0 +1,37 @@
+warning: this operation will panic at runtime
+  --> $DIR/erroneous-const2.rs:6:22
+   |
+LL |     const VOID: () = [()][2];
+   |                      ^^^^^^^ index out of bounds: the length is 1 but the index is 2
+   |
+note: the lint level is defined here
+  --> $DIR/erroneous-const2.rs:2:20
+   |
+LL | #![warn(const_err, unconditional_panic)]
+   |                    ^^^^^^^^^^^^^^^^^^^
+
+warning: any use of this value will cause an error
+  --> $DIR/erroneous-const2.rs:6:22
+   |
+LL |     const VOID: () = [()][2];
+   |     -----------------^^^^^^^-
+   |                      |
+   |                      index out of bounds: the length is 1 but the index is 2
+   |
+note: the lint level is defined here
+  --> $DIR/erroneous-const2.rs:2:9
+   |
+LL | #![warn(const_err, unconditional_panic)]
+   |         ^^^^^^^^^
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+error[E0080]: could not evaluate static initializer
+  --> $DIR/erroneous-const2.rs:15:17
+   |
+LL |         let _ = PrintName::<i32>::VOID;
+   |                 ^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
+
+error: aborting due to previous error; 2 warnings emitted
+
+For more information about this error, try `rustc --explain E0080`.