fix(#2407): respect the HaltIfNull opcode when determining nullability

sqlx-sqlite/src/connection/explain.rs

@@ -125,6 +125,7 @@ const OP_CONCAT: &str = "Concat";
 const OP_OFFSET_LIMIT: &str = "OffsetLimit";
 const OP_RESULT_ROW: &str = "ResultRow";
 const OP_HALT: &str = "Halt";
+const OP_HALT_IF_NULL: &str = "HaltIfNull";
 
 const MAX_LOOP_COUNT: u8 = 2;
 
@@ -942,6 +943,16 @@ pub(super) fn explain(
                     state.r.insert(p2, RegDataType::Single(ColumnType::null()));
                 }
 
+                // if there is a value in p3, and the query passes, then
+                // we know that it is not nullable
+                OP_HALT_IF_NULL => {
+                    if let Some(RegDataType::Single(ColumnType::Single { nullable, .. })) =
+                        state.r.get_mut(&p3)
+                    {
+                        *nullable = Some(false);
+                    }
+                }
+
                 OP_FUNCTION => {
                     // r[p1] = func( _ )
                     match from_utf8(p4).map_err(Error::protocol)? {

tests/sqlite/describe.rs

@@ -250,6 +250,22 @@ async fn it_describes_insert_with_returning() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[sqlx_macros::test]
+async fn it_describes_bound_columns_non_null() -> anyhow::Result<()> {
+    let mut conn = new::<Sqlite>().await?;
+    let d = conn
+        .describe("INSERT INTO tweet (id, text) VALUES ($1, $2) returning *")
+        .await?;
+
+    assert_eq!(d.columns().len(), 4);
+    assert_eq!(d.column(0).type_info().name(), "INTEGER");
+    assert_eq!(d.nullable(0), Some(false));
+    assert_eq!(d.column(1).type_info().name(), "TEXT");
+    assert_eq!(d.nullable(1), Some(false));
+
+    Ok(())
+}
+
 #[sqlx_macros::test]
 async fn it_describes_update_with_returning() -> anyhow::Result<()> {
     let mut conn = new::<Sqlite>().await?;