X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=compiler%2Frustc_parse%2Fsrc%2Fparser%2Fdiagnostics.rs;h=21d5bec65f03a8f57d2a19d087eb17f08836d315;hb=26e299a4a74e4526ee405476bf45559c434d28ce;hp=40daf4eb28fc1b558e78fbf8e1b016b048b731ac;hpb=f9b4976d60b51d6006c869e6362ce5b178e0f55e;p=rust.git

diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 40daf4eb28f..21d5bec65f0 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -2073,6 +2073,19 @@ pub fn recover_const_arg(
                     let value = self.mk_expr_err(start.to(expr.span));
                     err.emit();
                     return Ok(GenericArg::Const(AnonConst { id: ast::DUMMY_NODE_ID, value }));
+                } else if token::Colon == snapshot.token.kind
+                    && expr.span.lo() == snapshot.token.span.hi()
+                    && matches!(expr.kind, ExprKind::Path(..))
+                {
+                    // Find a mistake like "foo::var:A".
+                    err.span_suggestion(
+                        snapshot.token.span,
+                        "write a path separator here",
+                        "::".to_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                    err.emit();
+                    return Ok(GenericArg::Type(self.mk_ty(start.to(expr.span), TyKind::Err)));
                 } else if token::Comma == self.token.kind || self.token.kind.should_end_const_arg()
                 {
                     // Avoid the following output by checking that we consumed a full const arg: