From 2e4900f08504c96365b0c85aa5076dff864ce2e6 Mon Sep 17 00:00:00 2001
From: 132ikl <132@ikl.sh>
Date: Mon, 28 Jul 2025 22:24:12 -0400
Subject: [PATCH] Check type of row conditions at parse-time (#16175)
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# Description
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As a bonus to #16174, I realized it would be trivial to add a similar
check to where.

Before:
```nushell
1..100 | where 1
# => no output...
```

After:
```nushell
1..100 | where 1
# => Error: nu::parser::type_mismatch
# =>
# =>   × Type mismatch.
# =>    ╭─[entry #3:1:16]
# =>  1 │ 1..100 | where 1
# =>    ·                ┬
# =>    ·                ╰── expected bool, found int
# =>    ╰────
```

# User-Facing Changes
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helps us keep track of breaking changes. -->
* `where` should now error on row condition expressions which are not
booleans

# Tests + Formatting
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Added test

# After Submitting
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N/A
---
 crates/nu-parser/src/parser.rs | 12 +++++++++++-
 tests/repl/test_parser.rs      |  5 +++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/crates/nu-parser/src/parser.rs b/crates/nu-parser/src/parser.rs
index f02cd0857a..b1ca82106e 100644
--- a/crates/nu-parser/src/parser.rs
+++ b/crates/nu-parser/src/parser.rs
@@ -3742,7 +3742,17 @@ pub fn parse_row_condition(working_set: &mut StateWorkingSet, spans: &[Span]) ->
             return expression;
         }
         _ => {
-            // We have an expression, so let's convert this into a block.
+            // We have an expression, check that it's compatible with bool
+            if !type_compatible(&Type::Bool, &expression.ty) {
+                working_set.error(ParseError::TypeMismatch(
+                    Type::Bool,
+                    expression.ty.clone(),
+                    expression.span,
+                ));
+                return Expression::garbage(working_set, expression.span);
+            }
+
+            // Convert this expression into a block.
             let mut block = Block::new();
             let mut pipeline = Pipeline::new();
             pipeline.elements.push(PipelineElement {
diff --git a/tests/repl/test_parser.rs b/tests/repl/test_parser.rs
index 45b890653c..0cc4bc4cfe 100644
--- a/tests/repl/test_parser.rs
+++ b/tests/repl/test_parser.rs
@@ -618,6 +618,11 @@ fn single_value_row_condition() -> TestResult {
     )
 }
 
+#[test]
+fn row_condition_non_boolean() -> TestResult {
+    fail_test(r#"[1 2 3] | where 1"#, "expected bool")
+}
+
 #[test]
 fn performance_nested_lists() -> TestResult {
     // Parser used to be exponential on deeply nested lists