Merge 5d6b26d98d into a0d7c1a4fd

crates/nu-protocol/src/eval_const.rs

@@ -5,8 +5,9 @@
 use crate::{
     ast::{Assignment, Block, Call, Expr, Expression, ExternalArgument},
     debugger::{DebugContext, WithoutDebug},
-    engine::{EngineState, StateWorkingSet},
+    engine::{Closure, EngineState, StateWorkingSet},
     eval_base::Eval,
+    ir::Instruction,
     record, BlockId, Config, HistoryFileFormat, PipelineData, Record, ShellError, Span, Value,
     VarId,
 };
@@ -548,12 +549,41 @@ impl Eval for EvalConst {
     }
 
     fn eval_row_condition_or_closure(
-        _: &StateWorkingSet,
+        state: &StateWorkingSet,
         _: &mut (),
-        _: BlockId,
+        block_id: BlockId,
         span: Span,
     ) -> Result<Value, ShellError> {
-        Err(ShellError::NotAConstant { span })
+        let block = state.get_block(block_id);
+        let ir_block = block
+            .ir_block
+            .as_ref()
+            .ok_or(ShellError::NotAConstant { span })?;
+
+        let non_const_var_idx = ir_block.instructions.iter().position(|ins| {
+            let Instruction::LoadVariable { var_id, .. } = ins else {
+                return false;
+            };
+            let var = state.get_variable(*var_id);
+            !(var.const_val.is_some()
+                || block
+                    .span
+                    .is_some_and(|b| b.contains_span(var.declaration_span)))
+        });
+
+        if let Some(idx) = non_const_var_idx {
+            Err(ShellError::NotAConstant {
+                span: ir_block.spans[idx],
+            })
+        } else {
+            Ok(Value::closure(
+                Closure {
+                    block_id,
+                    captures: vec![],
+                },
+                span,
+            ))
+        }
     }
 
     fn eval_overlay(_: &StateWorkingSet, span: Span) -> Result<Value, ShellError> {