Use better error message for hard errors in CTFE

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -502,4 +502,14 @@ impl InterpError<'_> {
             _ => false,
         }
     }
+
+    /// Should this error be reported as a hard error, preventing compilation, or a soft error,
+    /// causing a deny-by-default lint?
+    pub fn is_hard_err(&self) -> bool {
+        use InterpError::*;
+        match *self {
+            MachineStop(ref err) => err.is_hard_err(),
+            _ => false,
+        }
+    }
 }

compiler/rustc_mir/src/const_eval/error.rs

@@ -157,7 +157,7 @@ impl<'tcx> ConstEvalErr<'tcx> {
         tcx: TyCtxtAt<'tcx>,
         message: &str,
         emit: impl FnOnce(DiagnosticBuilder<'_>),
-        mut lint_root: Option<hir::HirId>,
+        lint_root: Option<hir::HirId>,
     ) -> ErrorHandled {
         let finish = |mut err: DiagnosticBuilder<'_>, span_msg: Option<String>| {
             trace!("reporting const eval failure at {:?}", self.span);
@@ -194,12 +194,6 @@ impl<'tcx> ConstEvalErr<'tcx> {
             _ => {}
         };
 
-        // If we have a 'hard error', then set `lint_root` to `None` so that we don't
-        // emit a lint.
-        if matches!(&self.error, InterpError::MachineStop(err) if err.is_hard_err()) {
-            lint_root = None;
-        }
-
         let err_msg = self.error.to_string();
 
         // Regular case - emit a lint.

compiler/rustc_mir/src/const_eval/eval_queries.rs

@@ -312,22 +312,17 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
             let err = ConstEvalErr::new(&ecx, error, None);
             // Some CTFE errors raise just a lint, not a hard error; see
             // <https://github.com/rust-lang/rust/issues/71800>.
-            let emit_as_lint = if let Some(def) = def.as_local() {
+            let is_hard_err = if let Some(def) = def.as_local() {
                 // (Associated) consts only emit a lint, since they might be unused.
-                matches!(tcx.def_kind(def.did.to_def_id()), DefKind::Const | DefKind::AssocConst)
+                !matches!(tcx.def_kind(def.did.to_def_id()), DefKind::Const | DefKind::AssocConst)
+                    // check if the inner InterpError is hard
+                    || err.error.is_hard_err()
             } else {
                 // use of broken constant from other crate: always an error
-                false
+                true
             };
-            if emit_as_lint {
-                let hir_id = tcx.hir().local_def_id_to_hir_id(def.as_local().unwrap().did);
-                Err(err.report_as_lint(
-                    tcx.at(tcx.def_span(def.did)),
-                    "any use of this value will cause an error",
-                    hir_id,
-                    Some(err.span),
-                ))
-            } else {
+
+            if is_hard_err {
                 let msg = if is_static {
                     Cow::from("could not evaluate static initializer")
                 } else {
@@ -345,6 +340,14 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
                 };
 
                 Err(err.report_as_error(ecx.tcx.at(ecx.cur_span()), &msg))
+            } else {
+                let hir_id = tcx.hir().local_def_id_to_hir_id(def.as_local().unwrap().did);
+                Err(err.report_as_lint(
+                    tcx.at(tcx.def_span(def.did)),
+                    "any use of this value will cause an error",
+                    hir_id,
+                    Some(err.span),
+                ))
             }
         }
         Ok(mplace) => {

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

@@ -5,31 +5,31 @@
 const MSG: &str = "hello";
 
 const Z: () = std::panic!("cheese");
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Z2: () = std::panic!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Y: () = std::unreachable!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const X: () = std::unimplemented!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 //
 const W: () = std::panic!(MSG);
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Z_CORE: () = core::panic!("cheese");
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Z2_CORE: () = core::panic!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Y_CORE: () = core::unreachable!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const X_CORE: () = core::unimplemented!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const W_CORE: () = core::panic!(MSG);
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed

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

@@ -1,100 +1,80 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:7:15
    |
 LL | const Z: () = std::panic!("cheese");
-   | --------------^^^^^^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'cheese', $DIR/const_panic.rs:7:15
+   |               ^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'cheese', $DIR/const_panic.rs:7:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:10:16
    |
 LL | const Z2: () = std::panic!();
-   | ---------------^^^^^^^^^^^^^-
-   |                |
-   |                the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:10:16
+   |                ^^^^^^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:10:16
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:13:15
    |
 LL | const Y: () = std::unreachable!();
-   | --------------^^^^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:13:15
+   |               ^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:13:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:16:15
    |
 LL | const X: () = std::unimplemented!();
-   | --------------^^^^^^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:16:15
+   |               ^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:16:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:19:15
    |
 LL | const W: () = std::panic!(MSG);
-   | --------------^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'hello', $DIR/const_panic.rs:19:15
+   |               ^^^^^^^^^^^^^^^^ the evaluated program panicked at 'hello', $DIR/const_panic.rs:19:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:22:20
    |
 LL | const Z_CORE: () = core::panic!("cheese");
-   | -------------------^^^^^^^^^^^^^^^^^^^^^^-
-   |                    |
-   |                    the evaluated program panicked at 'cheese', $DIR/const_panic.rs:22:20
+   |                    ^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'cheese', $DIR/const_panic.rs:22:20
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:25:21
    |
 LL | const Z2_CORE: () = core::panic!();
-   | --------------------^^^^^^^^^^^^^^-
-   |                     |
-   |                     the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:25:21
+   |                     ^^^^^^^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/const_panic.rs:25:21
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:28:20
    |
 LL | const Y_CORE: () = core::unreachable!();
-   | -------------------^^^^^^^^^^^^^^^^^^^^-
-   |                    |
-   |                    the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:28:20
+   |                    ^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:28:20
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:31:20
    |
 LL | const X_CORE: () = core::unimplemented!();
-   | -------------------^^^^^^^^^^^^^^^^^^^^^^-
-   |                    |
-   |                    the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:31:20
+   |                    ^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:31:20
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:34:20
    |
 LL | const W_CORE: () = core::panic!(MSG);
-   | -------------------^^^^^^^^^^^^^^^^^-
-   |                    |
-   |                    the evaluated program panicked at 'hello', $DIR/const_panic.rs:34:20
+   |                    ^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'hello', $DIR/const_panic.rs:34:20
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 

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

@@ -7,13 +7,13 @@
 use core::panic::PanicInfo;
 
 const Z: () = panic!("cheese");
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const Y: () = unreachable!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 const X: () = unimplemented!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 #[lang = "eh_personality"]
 fn eh() {}

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

@@ -1,30 +1,24 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_libcore_bin.rs:9:15
    |
 LL | const Z: () = panic!("cheese");
-   | --------------^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'cheese', $DIR/const_panic_libcore_bin.rs:9:15
+   |               ^^^^^^^^^^^^^^^^ the evaluated program panicked at 'cheese', $DIR/const_panic_libcore_bin.rs:9:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_libcore_bin.rs:12:15
    |
 LL | const Y: () = unreachable!();
-   | --------------^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic_libcore_bin.rs:12:15
+   |               ^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic_libcore_bin.rs:12:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_libcore_bin.rs:15:15
    |
 LL | const X: () = unimplemented!();
-   | --------------^^^^^^^^^^^^^^^^-
-   |               |
-   |               the evaluated program panicked at 'not implemented', $DIR/const_panic_libcore_bin.rs:15:15
+   |               ^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic_libcore_bin.rs:15:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 

src/test/ui/consts/const-eval/panic-assoc-never-type.rs

@@ -9,7 +9,7 @@ struct PrintName;
 
 impl PrintName {
     const VOID: ! = panic!();
-    //~^ ERROR any use of this value will cause an error
+    //~^ ERROR evaluation of constant value failed
 }
 
 fn main() {

src/test/ui/consts/const-eval/panic-assoc-never-type.stderr

@@ -1,10 +1,8 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/panic-assoc-never-type.rs:11:21
    |
 LL |     const VOID: ! = panic!();
-   |     ----------------^^^^^^^^-
-   |                     |
-   |                     the evaluated program panicked at 'explicit panic', $DIR/panic-assoc-never-type.rs:11:21
+   |                     ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/panic-assoc-never-type.rs:11:21
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 

src/test/ui/consts/const-eval/panic-never-type.rs

@@ -4,7 +4,7 @@
 #![feature(never_type)]
 
 const VOID: ! = panic!();
-//~^ ERROR any use of this value will cause an error
+//~^ ERROR evaluation of constant value failed
 
 fn main() {
     let _ = VOID;

src/test/ui/consts/const-eval/panic-never-type.stderr

@@ -1,10 +1,8 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/panic-never-type.rs:6:17
    |
 LL | const VOID: ! = panic!();
-   | ----------------^^^^^^^^-
-   |                 |
-   |                 the evaluated program panicked at 'explicit panic', $DIR/panic-never-type.rs:6:17
+   |                 ^^^^^^^^ the evaluated program panicked at 'explicit panic', $DIR/panic-never-type.rs:6:17
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 

src/test/ui/consts/const-eval/unwind-abort.rs

@@ -2,7 +2,7 @@
 
 #[unwind(aborts)]
 const fn foo() {
-    panic!() //~ ERROR any use of this value will cause an error
+    panic!() //~ ERROR evaluation of constant value failed
 }
 
 const _: () = foo();

src/test/ui/consts/const-eval/unwind-abort.stderr

@@ -1,15 +1,14 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $DIR/unwind-abort.rs:5:5
    |
 LL |     panic!()
    |     ^^^^^^^^
    |     |
    |     the evaluated program panicked at 'explicit panic', $DIR/unwind-abort.rs:5:5
    |     inside `foo` at $SRC_DIR/std/src/panic.rs:LL:COL
-   |     inside `_` at $DIR/unwind-abort.rs:8:15
 ...
 LL | const _: () = foo();
-   | --------------------
+   |               ----- inside `_` at $DIR/unwind-abort.rs:8:15
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 

src/test/ui/consts/const-unwrap.stderr

@@ -1,17 +1,16 @@
-error[E0080]: any use of this value will cause an error
+error[E0080]: evaluation of constant value failed
   --> $SRC_DIR/core/src/option.rs:LL:COL
    |
 LL |             None => panic!("called `Option::unwrap()` on a `None` value"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                     |
    |                     the evaluated program panicked at 'called `Option::unwrap()` on a `None` value', $DIR/const-unwrap.rs:9:38
    |                     inside `Option::<i32>::unwrap` at $SRC_DIR/core/src/panic.rs:LL:COL
-   |                     inside `BAR` at $DIR/const-unwrap.rs:9:18
    | 
-  ::: $DIR/const-unwrap.rs:9:1
+  ::: $DIR/const-unwrap.rs:9:18
    |
 LL | const BAR: i32 = Option::<i32>::None.unwrap();
-   | ----------------------------------------------
+   |                  ---------------------------- inside `BAR` at $DIR/const-unwrap.rs:9:18
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)