Rollup merge of #122440 - RalfJung:required-consts, r=oli-obk

const-eval: organize and extend tests for required-consts

This includes some tests that are known-broken and hence disabled (due to https://github.com/rust-lang/rust/issues/107503).

r? `````@oli-obk`````

tests/ui/consts/const-eval/erroneous-const.stderr

@@ -1,15 +0,0 @@
-error[E0080]: evaluation of `PrintName::<i32>::VOID` failed
-  --> $DIR/erroneous-const.rs:6:22
-   |
-LL |     const VOID: () = [()][2];
-   |                      ^^^^^^^ index out of bounds: the length is 1 but the index is 2
-
-note: erroneous constant encountered
-  --> $DIR/erroneous-const.rs:13:13
-   |
-LL |             PrintName::<T>::VOID;
-   |             ^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/const-eval/erroneous-const2.rs

@@ -1,19 +0,0 @@
-//! Make sure we error on erroneous consts even if they are unused.
-#![allow(unconditional_panic)]
-
-struct PrintName<T>(T);
-impl<T> PrintName<T> {
-    const VOID: () = [()][2]; //~ERROR evaluation of `PrintName::<i32>::VOID` failed
-}
-
-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.
-        PrintName::<i32>::VOID; //~ constant
-    }
-};
-
-fn main() {
-    FOO
-}

tests/ui/consts/const-eval/erroneous-const2.stderr

@@ -1,15 +0,0 @@
-error[E0080]: evaluation of `PrintName::<i32>::VOID` failed
-  --> $DIR/erroneous-const2.rs:6:22
-   |
-LL |     const VOID: () = [()][2];
-   |                      ^^^^^^^ index out of bounds: the length is 1 but the index is 2
-
-note: erroneous constant encountered
-  --> $DIR/erroneous-const2.rs:13:9
-   |
-LL |         PrintName::<i32>::VOID;
-   |         ^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/const-eval/unused-broken-const-late.stderr

@@ -1,11 +0,0 @@
-error[E0080]: evaluation of `PrintName::<i32>::VOID` failed
-  --> $DIR/unused-broken-const-late.rs:8:22
-   |
-LL |     const VOID: () = panic!();
-   |                      ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/unused-broken-const-late.rs:8:22
-   |
-   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-called-fn.noopt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-called-fn.rs:9:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-called-fn.rs:9:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn called::<i32>`
+  --> $DIR/collect-in-called-fn.rs:23:5
+   |
+LL |     called::<i32>();
+   |     ^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-called-fn.opt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-called-fn.rs:9:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-called-fn.rs:9:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn called::<i32>`
+  --> $DIR/collect-in-called-fn.rs:23:5
+   |
+LL |     called::<i32>();
+   |     ^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-called-fn.rs

@@ -1,20 +1,24 @@
+//@revisions: noopt opt
 //@ build-fail
-//@ compile-flags: -O
+//@[opt] compile-flags: -O
 //! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
 //! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
 
-struct PrintName<T>(T);
-impl<T> PrintName<T> {
-    const VOID: () = panic!(); //~ERROR evaluation of `PrintName::<i32>::VOID` failed
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //~ERROR evaluation of `Fail::<i32>::C` failed
 }
 
-fn no_codegen<T>() {
+#[inline(never)]
+fn called<T>() {
     // Any function that is called is guaranteed to have all consts that syntactically
     // appear in its body evaluated, even if they only appear in dead code.
+    // This relies on mono-item collection checking `required_consts` in collected functions.
     if false {
-        let _ = PrintName::<T>::VOID;
+        let _ = Fail::<T>::C;
     }
 }
+
 pub fn main() {
-    no_codegen::<i32>();
+    called::<i32>();
 }

tests/ui/consts/required-consts/collect-in-dead-drop.noopt.stderr

@@ -0,0 +1,14 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-dead-drop.rs:12:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-dead-drop.rs:12:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn <Fail<i32> as std::ops::Drop>::drop`
+  --> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-dead-drop.rs

@@ -0,0 +1,33 @@
+//@revisions: noopt opt
+//@[noopt] build-fail
+//@[opt] compile-flags: -O
+//FIXME: `opt` revision currently does not stop with an error due to
+//<https://github.com/rust-lang/rust/issues/107503>.
+//@[opt] build-pass
+//! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
+//! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //[noopt]~ERROR evaluation of `Fail::<i32>::C` failed
+}
+
+// This function is not actually called, but is mentioned implicitly as destructor in dead code in a
+// function that is called. Make sure we still find this error.
+impl<T> Drop for Fail<T> {
+    fn drop(&mut self) {
+        let _ = Fail::<T>::C;
+    }
+}
+
+#[inline(never)]
+fn called<T>(x: T) {
+    if false {
+        let v = Fail(x);
+        // Now it gest dropped implicitly, at the end of this scope.
+    }
+}
+
+pub fn main() {
+    called::<i32>(0);
+}

tests/ui/consts/required-consts/collect-in-dead-fn.noopt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-dead-fn.rs:12:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-dead-fn.rs:12:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn not_called::<i32>`
+  --> $DIR/collect-in-dead-fn.rs:29:9
+   |
+LL |         not_called::<T>();
+   |         ^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-dead-fn.rs

@@ -0,0 +1,35 @@
+//@revisions: noopt opt
+//@[noopt] build-fail
+//@[opt] compile-flags: -O
+//FIXME: `opt` revision currently does not stop with an error due to
+//<https://github.com/rust-lang/rust/issues/107503>.
+//@[opt] build-pass
+//! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
+//! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //[noopt]~ERROR evaluation of `Fail::<i32>::C` failed
+}
+
+// This function is not actually called, but it is mentioned in dead code in a function that is
+// called. Make sure we still find this error.
+// This relies on mono-item collection checking `required_consts` in functions that syntactically
+// are called in collected functions (even inside dead code).
+#[inline(never)]
+fn not_called<T>() {
+    if false {
+        let _ = Fail::<T>::C;
+    }
+}
+
+#[inline(never)]
+fn called<T>() {
+    if false {
+        not_called::<T>();
+    }
+}
+
+pub fn main() {
+    called::<i32>();
+}

tests/ui/consts/required-consts/collect-in-dead-forget.rs

@@ -0,0 +1,32 @@
+//@revisions: noopt opt
+//@build-pass
+//@[opt] compile-flags: -O
+//! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
+//! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!();
+}
+
+// This function is not actually called, but is mentioned implicitly as destructor in dead code in a
+// function that is called. Make sure we still find this error.
+impl<T> Drop for Fail<T> {
+    fn drop(&mut self) {
+        let _ = Fail::<T>::C;
+    }
+}
+
+#[inline(never)]
+fn called<T>(x: T) {
+    if false {
+        let v = Fail(x);
+        std::mem::forget(v);
+        // Now the destructor never gets "mentioned" so this build should *not* fail.
+        // IOW, this demonstrates that we are using a post-drop-elab notion of "mentioned".
+    }
+}
+
+pub fn main() {
+    called::<i32>(0);
+}

tests/ui/consts/required-consts/collect-in-dead-move.noopt.stderr

@@ -0,0 +1,14 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-dead-move.rs:12:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-dead-move.rs:12:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn <Fail<i32> as std::ops::Drop>::drop`
+  --> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-dead-move.rs

@@ -0,0 +1,33 @@
+//@revisions: noopt opt
+//@[noopt] build-fail
+//@[opt] compile-flags: -O
+//FIXME: `opt` revision currently does not stop with an error due to
+//<https://github.com/rust-lang/rust/issues/107503>.
+//@[opt] build-pass
+//! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
+//! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //[noopt]~ERROR evaluation of `Fail::<i32>::C` failed
+}
+
+// This function is not actually called, but is mentioned implicitly as destructor in dead code in a
+// function that is called. Make sure we still find this error.
+impl<T> Drop for Fail<T> {
+    fn drop(&mut self) {
+        let _ = Fail::<T>::C;
+    }
+}
+
+#[inline(never)]
+fn called<T>(x: T) {
+    if false {
+        let v = Fail(x);
+        drop(v); // move `v` away (and it then gets dropped there so build still fails)
+    }
+}
+
+pub fn main() {
+    called::<i32>(0);
+}

tests/ui/consts/required-consts/collect-in-dead-vtable.noopt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/collect-in-dead-vtable.rs:12:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/collect-in-dead-vtable.rs:12:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: the above error was encountered while instantiating `fn <std::vec::Vec<i32> as MyTrait>::not_called`
+  --> $DIR/collect-in-dead-vtable.rs:35:40
+   |
+LL |         let gen_vtable: &dyn MyTrait = &v; // vtable "appears" here
+   |                                        ^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/collect-in-dead-vtable.rs

@@ -0,0 +1,41 @@
+//@revisions: noopt opt
+//@[noopt] build-fail
+//@[opt] compile-flags: -O
+//FIXME: `opt` revision currently does not stop with an error due to
+//<https://github.com/rust-lang/rust/issues/107503>.
+//@[opt] build-pass
+//! Make sure we detect erroneous constants post-monomorphization even when they are unused. This is
+//! crucial, people rely on it for soundness. (https://github.com/rust-lang/rust/issues/112090)
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //[noopt]~ERROR evaluation of `Fail::<i32>::C` failed
+}
+
+trait MyTrait {
+    fn not_called(&self);
+}
+
+// This function is not actually called, but it is mentioned in a vtable in a function that is
+// called. Make sure we still find this error.
+// This relies on mono-item collection checking `required_consts` in functions that are referenced
+// in vtables that syntactically appear in collected functions (even inside dead code).
+impl<T> MyTrait for Vec<T> {
+    fn not_called(&self) {
+        if false {
+            let _ = Fail::<T>::C;
+        }
+    }
+}
+
+#[inline(never)]
+fn called<T>() {
+    if false {
+        let v: Vec<T> = Vec::new();
+        let gen_vtable: &dyn MyTrait = &v; // vtable "appears" here
+    }
+}
+
+pub fn main() {
+    called::<i32>();
+}

tests/ui/consts/required-consts/interpret-in-const-called-fn.noopt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/interpret-in-const-called-fn.rs:7:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/interpret-in-const-called-fn.rs:7:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-const-called-fn.rs:16:9
+   |
+LL |         Fail::<T>::C;
+   |         ^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-const-called-fn.opt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/interpret-in-const-called-fn.rs:7:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/interpret-in-const-called-fn.rs:7:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-const-called-fn.rs:16:9
+   |
+LL |         Fail::<T>::C;
+   |         ^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-const-called-fn.rs

@@ -1,16 +1,19 @@
+//@revisions: noopt opt
+//@[opt] compile-flags: -O
 //! Make sure we error on erroneous consts even if they are unused.
-#![allow(unconditional_panic)]
 
-struct PrintName<T>(T);
-impl<T> PrintName<T> {
-    const VOID: () = [()][2]; //~ERROR evaluation of `PrintName::<i32>::VOID` failed
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //~ERROR evaluation of `Fail::<i32>::C` failed
 }
 
+#[inline(never)]
 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.
-            PrintName::<T>::VOID; //~ constant
+        // This relies on const-eval evaluating all `required_consts` of `const fn`.
+        Fail::<T>::C; //~ constant
     }
 }
 

tests/ui/consts/required-consts/interpret-in-promoted.noopt.stderr

@@ -0,0 +1,27 @@
+error[E0080]: evaluation of constant value failed
+  --> $SRC_DIR/core/src/hint.rs:LL:COL
+   |
+   = note: entering unreachable code
+   |
+note: inside `unreachable_unchecked`
+  --> $SRC_DIR/core/src/hint.rs:LL:COL
+note: inside `ub`
+  --> $DIR/interpret-in-promoted.rs:6:5
+   |
+LL |     std::hint::unreachable_unchecked();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: inside `FOO`
+  --> $DIR/interpret-in-promoted.rs:12:28
+   |
+LL |     let _x: &'static () = &ub();
+   |                            ^^^^
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-promoted.rs:12:27
+   |
+LL |     let _x: &'static () = &ub();
+   |                           ^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-promoted.opt.stderr

@@ -0,0 +1,27 @@
+error[E0080]: evaluation of constant value failed
+  --> $SRC_DIR/core/src/hint.rs:LL:COL
+   |
+   = note: entering unreachable code
+   |
+note: inside `unreachable_unchecked`
+  --> $SRC_DIR/core/src/hint.rs:LL:COL
+note: inside `ub`
+  --> $DIR/interpret-in-promoted.rs:6:5
+   |
+LL |     std::hint::unreachable_unchecked();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: inside `FOO`
+  --> $DIR/interpret-in-promoted.rs:12:28
+   |
+LL |     let _x: &'static () = &ub();
+   |                            ^^^^
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-promoted.rs:12:27
+   |
+LL |     let _x: &'static () = &ub();
+   |                           ^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-promoted.rs

@@ -0,0 +1,15 @@
+//@revisions: noopt opt
+//@[opt] compile-flags: -O
+//! Make sure we error on erroneous consts even if they are unused.
+
+const unsafe fn ub() {
+    std::hint::unreachable_unchecked();
+}
+
+pub const FOO: () = unsafe {
+    // Make sure that this gets promoted and then fails to evaluate, and we deal with that
+    // correctly.
+    let _x: &'static () = &ub(); //~ erroneous constant
+};
+
+fn main() {}

tests/ui/consts/required-consts/interpret-in-static.noopt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/interpret-in-static.rs:7:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/interpret-in-static.rs:7:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-static.rs:15:9
+   |
+LL |         Fail::<i32>::C;
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-static.opt.stderr

@@ -0,0 +1,17 @@
+error[E0080]: evaluation of `Fail::<i32>::C` failed
+  --> $DIR/interpret-in-static.rs:7:19
+   |
+LL |     const C: () = panic!();
+   |                   ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/interpret-in-static.rs:7:19
+   |
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+note: erroneous constant encountered
+  --> $DIR/interpret-in-static.rs:15:9
+   |
+LL |         Fail::<i32>::C;
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0080`.

tests/ui/consts/required-consts/interpret-in-static.rs

@@ -0,0 +1,21 @@
+//@revisions: noopt opt
+//@[opt] compile-flags: -O
+//! Make sure we error on erroneous consts even if they are unused.
+
+struct Fail<T>(T);
+impl<T> Fail<T> {
+    const C: () = panic!(); //~ERROR evaluation of `Fail::<i32>::C` failed
+}
+
+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.
+        // This relies on const-eval evaluating all `required_consts` of the `static` MIR body.
+        Fail::<i32>::C; //~ constant
+    }
+};
+
+fn main() {
+    FOO
+}