make const_err a hard error

compiler/rustc_const_eval/src/const_eval/error.rs

@@ -2,7 +2,6 @@ use std::error::Error;
 use std::fmt;
 
 use rustc_errors::Diagnostic;
-use rustc_hir as hir;
 use rustc_middle::mir::AssertKind;
 use rustc_middle::ty::{layout::LayoutError, query::TyCtxtAt, ConstInt};
 use rustc_span::{Span, Symbol};
@@ -23,11 +22,7 @@ pub enum ConstEvalErrKind {
     Abort(String),
 }
 
-impl MachineStopType for ConstEvalErrKind {
-    fn is_hard_err(&self) -> bool {
-        matches!(self, Self::Panic { .. })
-    }
-}
+impl MachineStopType for ConstEvalErrKind {}
 
 // The errors become `MachineStop` with plain strings when being raised.
 // `ConstEvalErr` (in `librustc_middle/mir/interpret/error.rs`) knows to
@@ -87,48 +82,10 @@ impl<'tcx> ConstEvalErr<'tcx> {
         ConstEvalErr { error: error.into_kind(), stacktrace, span }
     }
 
-    pub fn struct_error(
-        &self,
-        tcx: TyCtxtAt<'tcx>,
-        message: &str,
-        decorate: impl FnOnce(&mut Diagnostic),
-    ) -> ErrorHandled {
-        self.struct_generic(tcx, message, decorate, None)
-    }
-
     pub fn report_as_error(&self, tcx: TyCtxtAt<'tcx>, message: &str) -> ErrorHandled {
         self.struct_error(tcx, message, |_| {})
     }
 
-    pub fn report_as_lint(
-        &self,
-        tcx: TyCtxtAt<'tcx>,
-        message: &str,
-        lint_root: hir::HirId,
-        span: Option<Span>,
-    ) -> ErrorHandled {
-        self.struct_generic(
-            tcx,
-            message,
-            |lint: &mut Diagnostic| {
-                // Apply the span.
-                if let Some(span) = span {
-                    let primary_spans = lint.span.primary_spans().to_vec();
-                    // point at the actual error as the primary span
-                    lint.replace_span_with(span);
-                    // point to the `const` statement as a secondary span
-                    // they don't have any label
-                    for sp in primary_spans {
-                        if sp != span {
-                            lint.span_label(sp, "");
-                        }
-                    }
-                }
-            },
-            Some(lint_root),
-        )
-    }
-
     /// Create a diagnostic for this const eval error.
     ///
     /// Sets the message passed in via `message` and adds span labels with detailed error
@@ -137,13 +94,12 @@ impl<'tcx> ConstEvalErr<'tcx> {
     ///
     /// If `lint_root.is_some()` report it as a lint, else report it as a hard error.
     /// (Except that for some errors, we ignore all that -- see `must_error` below.)
-    #[instrument(skip(self, tcx, decorate, lint_root), level = "debug")]
-    fn struct_generic(
+    #[instrument(skip(self, tcx, decorate), level = "debug")]
+    pub fn struct_error(
         &self,
         tcx: TyCtxtAt<'tcx>,
         message: &str,
         decorate: impl FnOnce(&mut Diagnostic),
-        lint_root: Option<hir::HirId>,
     ) -> ErrorHandled {
         let finish = |err: &mut Diagnostic, span_msg: Option<String>| {
             trace!("reporting const eval failure at {:?}", self.span);
@@ -224,27 +180,9 @@ impl<'tcx> ConstEvalErr<'tcx> {
 
         let err_msg = self.error.to_string();
 
-        // Regular case - emit a lint.
-        if let Some(lint_root) = lint_root {
-            // Report as lint.
-            let hir_id =
-                self.stacktrace.iter().rev().find_map(|frame| frame.lint_root).unwrap_or(lint_root);
-            tcx.struct_span_lint_hir(
-                rustc_session::lint::builtin::CONST_ERR,
-                hir_id,
-                tcx.span,
-                message,
-                |lint| {
-                    finish(lint, Some(err_msg));
-                    lint
-                },
-            );
-            ErrorHandled::Linted
-        } else {
-            // Report as hard error.
-            let mut err = struct_error(tcx, message);
-            finish(&mut err, Some(err_msg));
-            ErrorHandled::Reported(err.emit())
-        }
+        // Report as hard error.
+        let mut err = struct_error(tcx, message);
+        finish(&mut err, Some(err_msg));
+        ErrorHandled::Reported(err.emit())
     }
 }

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -317,45 +317,23 @@ pub fn eval_to_allocation_raw_provider<'tcx>(
     match res.and_then(|body| eval_body_using_ecx(&mut ecx, cid, &body)) {
         Err(error) => {
             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 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)
-                    // check if the inner InterpError is hard
-                    || err.error.is_hard_err()
+            let msg = if is_static {
+                Cow::from("could not evaluate static initializer")
             } else {
-                // use of broken constant from other crate: always an error
-                true
+                // If the current item has generics, we'd like to enrich the message with the
+                // instance and its substs: to show the actual compile-time values, in addition to
+                // the expression, leading to the const eval error.
+                let instance = &key.value.instance;
+                if !instance.substs.is_empty() {
+                    let instance = with_no_trimmed_paths!(instance.to_string());
+                    let msg = format!("evaluation of `{}` failed", instance);
+                    Cow::from(msg)
+                } else {
+                    Cow::from("evaluation of constant value failed")
+                }
             };
 
-            if is_hard_err {
-                let msg = if is_static {
-                    Cow::from("could not evaluate static initializer")
-                } else {
-                    // If the current item has generics, we'd like to enrich the message with the
-                    // instance and its substs: to show the actual compile-time values, in addition to
-                    // the expression, leading to the const eval error.
-                    let instance = &key.value.instance;
-                    if !instance.substs.is_empty() {
-                        let instance = with_no_trimmed_paths!(instance.to_string());
-                        let msg = format!("evaluation of `{}` failed", instance);
-                        Cow::from(msg)
-                    } else {
-                        Cow::from("evaluation of constant value failed")
-                    }
-                };
-
-                Err(err.report_as_error(ecx.tcx.at(err.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),
-                ))
-            }
+            Err(err.report_as_error(ecx.tcx.at(err.span), &msg))
         }
         Ok(mplace) => {
             // Since evaluation had no errors, validate the resulting constant.

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -258,6 +258,9 @@ impl<'tcx> fmt::Display for FrameInfo<'tcx> {
             {
                 write!(f, "inside closure")?;
             } else {
+                // Note: this triggers a `good_path_bug` state, which means that if we ever get here
+                // we must emit a diagnostic. We should never display a `FrameInfo` unless we
+                // actually want to emit a warning or error to the user.
                 write!(f, "inside `{}`", self.instance)?;
             }
             if !self.span.is_dummy() {

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -332,8 +332,6 @@ pub enum InternKind {
 ///
 /// This *cannot raise an interpreter error*.  Doing so is left to validation, which
 /// tracks where in the value we are and thus can show much better error messages.
-/// Any errors here would anyway be turned into `const_err` lints, whereas validation failures
-/// are hard errors.
 #[instrument(level = "debug", skip(ecx))]
 pub fn intern_const_alloc_recursive<
     'mir,