report_not_const_evaluatable_error to avoid ICEing on ConstKind::Expr

Author: lenko-d

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -3252,20 +3252,31 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         }
 
         match obligation.predicate.kind().skip_binder() {
-            ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(ct)) => {
-                let ty::ConstKind::Unevaluated(uv) = ct.kind() else {
+            ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(ct)) => match ct.kind() {
+                ty::ConstKind::Unevaluated(uv) => {
+                    let mut err =
+                        self.tcx.sess.struct_span_err(span, "unconstrained generic constant");
+                    let const_span = self.tcx.def_span(uv.def);
+                    match self.tcx.sess.source_map().span_to_snippet(const_span) {
+                            Ok(snippet) => err.help(format!(
+                                "try adding a `where` bound using this expression: `where [(); {snippet}]:`"
+                            )),
+                            _ => err.help("consider adding a `where` bound using this expression"),
+                        };
+                    Some(err)
+                }
+                ty::ConstKind::Expr(_) => {
+                    let mut err = self
+                        .tcx
+                        .sess
+                        .struct_span_err(span, "evaluation of ConstKind::Expr is not supported");
+                    err.emit();
+                    None
+                }
+                _ => {
                     bug!("const evaluatable failed for non-unevaluated const `{ct:?}`");
-                };
-                let mut err = self.tcx.sess.struct_span_err(span, "unconstrained generic constant");
-                let const_span = self.tcx.def_span(uv.def);
-                match self.tcx.sess.source_map().span_to_snippet(const_span) {
-                    Ok(snippet) => err.help(format!(
-                        "try adding a `where` bound using this expression: `where [(); {snippet}]:`"
-                    )),
-                    _ => err.help("consider adding a `where` bound using this expression"),
-                };
-                Some(err)
-            }
+                }
+            },
             _ => {
                 span_bug!(
                     span,

tests/ui/const-generics/generic_const_exprs/const_kind_expr/issue_114151.rs

@@ -0,0 +1,25 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+fn foo<const N: usize>(
+    _: [u8; {
+        {
+            N
+        }
+    }],
+) {
+}
+
+fn ice<const L: usize>()
+where
+    [(); (L - 1) + 1 + L]:,
+{
+    foo::<_, L>([(); L + 1 + L]);
+    //~^ ERROR: mismatched types
+    //~^^ ERROR: unconstrained generic constant
+    //~^^^ ERROR: function takes 1 generic argument but 2 generic arguments were supplied
+    //~^^^^ ERROR: unconstrained generic constant
+    //~^^^^^ ERROR: evaluation of ConstKind::Expr is not supported
+}
+
+fn main() {}

tests/ui/const-generics/generic_const_exprs/const_kind_expr/issue_114151.stderr

@@ -0,0 +1,64 @@
+error[E0107]: function takes 1 generic argument but 2 generic arguments were supplied
+  --> $DIR/issue_114151.rs:17:5
+   |
+LL |     foo::<_, L>([(); L + 1 + L]);
+   |     ^^^      - help: remove this generic argument
+   |     |
+   |     expected 1 generic argument
+   |
+note: function defined here, with 1 generic parameter: `N`
+  --> $DIR/issue_114151.rs:4:4
+   |
+LL | fn foo<const N: usize>(
+   |    ^^^ --------------
+
+error[E0308]: mismatched types
+  --> $DIR/issue_114151.rs:17:18
+   |
+LL |     foo::<_, L>([(); L + 1 + L]);
+   |                  ^^ expected `u8`, found `()`
+
+error: unconstrained generic constant
+  --> $DIR/issue_114151.rs:17:22
+   |
+LL |     foo::<_, L>([(); L + 1 + L]);
+   |                      ^^^^^^^^^
+   |
+   = help: try adding a `where` bound using this expression: `where [(); L + 1 + L]:`
+
+error: unconstrained generic constant
+  --> $DIR/issue_114151.rs:17:17
+   |
+LL |     foo::<_, L>([(); L + 1 + L]);
+   |     ----------- ^^^^^^^^^^^^^^^
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: try adding a `where` bound using this expression: `where [(); {
+                   {
+                       N
+                   }
+               }]:`
+note: required by a bound in `foo`
+  --> $DIR/issue_114151.rs:5:13
+   |
+LL |   fn foo<const N: usize>(
+   |      --- required by a bound in this function
+LL |       _: [u8; {
+   |  _____________^
+LL | |         {
+LL | |             N
+LL | |         }
+LL | |     }],
+   | |_____^ required by this bound in `foo`
+
+error: evaluation of ConstKind::Expr is not supported
+  --> $DIR/issue_114151.rs:17:5
+   |
+LL |     foo::<_, L>([(); L + 1 + L]);
+   |     ^^^^^^^^^^^
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0107, E0308.
+For more information about an error, try `rustc --explain E0107`.