fix: Fix struct literals (#19214)

crates/polars-plan/src/plans/conversion/expr_to_ir.rs

@@ -96,7 +96,7 @@ fn to_aexpr_impl_materialized_lit(
     let e = match expr {
         Expr::Literal(lv @ LiteralValue::Int(_) | lv @ LiteralValue::Float(_)) => {
             let av = lv.to_any_value().unwrap();
-            Expr::Literal(LiteralValue::try_from(av).unwrap())
+            Expr::Literal(LiteralValue::from(av))
         },
         Expr::Alias(inner, name)
             if matches!(
@@ -109,10 +109,7 @@ fn to_aexpr_impl_materialized_lit(
                 unreachable!()
             };
             let av = lv.to_any_value().unwrap();
-            Expr::Alias(
-                Arc::new(Expr::Literal(LiteralValue::try_from(av).unwrap())),
-                name,
-            )
+            Expr::Alias(Arc::new(Expr::Literal(LiteralValue::from(av))), name)
         },
         e => e,
     };

crates/polars-plan/src/plans/conversion/type_coercion/mod.rs

@@ -419,7 +419,7 @@ fn inline_or_prune_cast(
             },
             LiteralValue::StrCat(s) => {
                 let av = AnyValue::String(s).strict_cast(dtype);
-                return Ok(av.map(|av| AExpr::Literal(av.try_into().unwrap())));
+                return Ok(av.map(|av| AExpr::Literal(av.into())));
             },
             // We generate casted literal datetimes, so ensure we cast upon conversion
             // to create simpler expr trees.
@@ -431,7 +431,7 @@ fn inline_or_prune_cast(
             lv @ (LiteralValue::Int(_) | LiteralValue::Float(_)) => {
                 let av = lv.to_any_value().ok_or_else(|| polars_err!(InvalidOperation: "literal value: {:?} too large for Polars", lv))?;
                 let av = av.strict_cast(dtype);
-                return Ok(av.map(|av| AExpr::Literal(av.try_into().unwrap())));
+                return Ok(av.map(|av| AExpr::Literal(av.into())));
             },
             LiteralValue::Null => match dtype {
                 DataType::Unknown(UnknownKind::Float | UnknownKind::Int(_) | UnknownKind::Str) => {
@@ -469,7 +469,7 @@ fn inline_or_prune_cast(
                                 None => return Ok(None),
                             }
                         };
-                        out.try_into()?
+                        out.into()
                     },
                 }
             },

crates/polars-plan/src/plans/lit.rs

@@ -92,7 +92,7 @@ impl LiteralValue {
         match self {
             LiteralValue::Int(_) | LiteralValue::Float(_) | LiteralValue::StrCat(_) => {
                 let av = self.to_any_value().unwrap();
-                av.try_into().unwrap()
+                av.into()
             },
             lv => lv,
         }
@@ -284,55 +284,52 @@ impl<'a> Literal for &'a [u8] {
     }
 }
 
-impl TryFrom<AnyValue<'_>> for LiteralValue {
-    type Error = PolarsError;
-    fn try_from(value: AnyValue) -> PolarsResult<Self> {
+impl From<AnyValue<'_>> for LiteralValue {
+    fn from(value: AnyValue) -> Self {
         match value {
-            AnyValue::Null => Ok(Self::Null),
-            AnyValue::Boolean(b) => Ok(Self::Boolean(b)),
-            AnyValue::String(s) => Ok(Self::String(PlSmallStr::from_str(s))),
-            AnyValue::Binary(b) => Ok(Self::Binary(b.to_vec())),
+            AnyValue::Null => Self::Null,
+            AnyValue::Boolean(b) => Self::Boolean(b),
+            AnyValue::String(s) => Self::String(PlSmallStr::from_str(s)),
+            AnyValue::Binary(b) => Self::Binary(b.to_vec()),
             #[cfg(feature = "dtype-u8")]
-            AnyValue::UInt8(u) => Ok(Self::UInt8(u)),
+            AnyValue::UInt8(u) => Self::UInt8(u),
             #[cfg(feature = "dtype-u16")]
-            AnyValue::UInt16(u) => Ok(Self::UInt16(u)),
-            AnyValue::UInt32(u) => Ok(Self::UInt32(u)),
-            AnyValue::UInt64(u) => Ok(Self::UInt64(u)),
+            AnyValue::UInt16(u) => Self::UInt16(u),
+            AnyValue::UInt32(u) => Self::UInt32(u),
+            AnyValue::UInt64(u) => Self::UInt64(u),
             #[cfg(feature = "dtype-i8")]
-            AnyValue::Int8(i) => Ok(Self::Int8(i)),
+            AnyValue::Int8(i) => Self::Int8(i),
             #[cfg(feature = "dtype-i16")]
-            AnyValue::Int16(i) => Ok(Self::Int16(i)),
-            AnyValue::Int32(i) => Ok(Self::Int32(i)),
-            AnyValue::Int64(i) => Ok(Self::Int64(i)),
-            AnyValue::Float32(f) => Ok(Self::Float32(f)),
-            AnyValue::Float64(f) => Ok(Self::Float64(f)),
+            AnyValue::Int16(i) => Self::Int16(i),
+            AnyValue::Int32(i) => Self::Int32(i),
+            AnyValue::Int64(i) => Self::Int64(i),
+            AnyValue::Float32(f) => Self::Float32(f),
+            AnyValue::Float64(f) => Self::Float64(f),
             #[cfg(feature = "dtype-decimal")]
-            AnyValue::Decimal(v, scale) => Ok(Self::Decimal(v, scale)),
+            AnyValue::Decimal(v, scale) => Self::Decimal(v, scale),
             #[cfg(feature = "dtype-date")]
-            AnyValue::Date(v) => Ok(LiteralValue::Date(v)),
+            AnyValue::Date(v) => LiteralValue::Date(v),
             #[cfg(feature = "dtype-datetime")]
-            AnyValue::Datetime(value, tu, tz) => Ok(LiteralValue::DateTime(value, tu, tz.cloned())),
+            AnyValue::Datetime(value, tu, tz) => LiteralValue::DateTime(value, tu, tz.cloned()),
             #[cfg(feature = "dtype-duration")]
-            AnyValue::Duration(value, tu) => Ok(LiteralValue::Duration(value, tu)),
+            AnyValue::Duration(value, tu) => LiteralValue::Duration(value, tu),
             #[cfg(feature = "dtype-time")]
-            AnyValue::Time(v) => Ok(LiteralValue::Time(v)),
-            AnyValue::List(l) => Ok(Self::Series(SpecialEq::new(l))),
-            AnyValue::StringOwned(o) => Ok(Self::String(o)),
+            AnyValue::Time(v) => LiteralValue::Time(v),
+            AnyValue::List(l) => Self::Series(SpecialEq::new(l)),
+            AnyValue::StringOwned(o) => Self::String(o),
             #[cfg(feature = "dtype-categorical")]
             AnyValue::Categorical(c, rev_mapping, arr) | AnyValue::Enum(c, rev_mapping, arr) => {
                 if arr.is_null() {
-                    Ok(Self::String(PlSmallStr::from_str(rev_mapping.get(c))))
+                    Self::String(PlSmallStr::from_str(rev_mapping.get(c)))
                 } else {
                     unsafe {
-                        Ok(Self::String(PlSmallStr::from_str(
+                        Self::String(PlSmallStr::from_str(
                             arr.deref_unchecked().value(c as usize),
-                        )))
+                        ))
                     }
                 }
             },
-            v => polars_bail!(
-                ComputeError: "cannot convert any-value {:?} to literal", v
-            ),
+            _ => LiteralValue::OtherScalar(Scalar::new(value.dtype(), value.into_static())),
         }
     }
 }

crates/polars-python/src/functions/lazy.rs

@@ -478,7 +478,7 @@ pub fn lit(value: &Bound<'_, PyAny>, allow_object: bool, is_scalar: bool) -> PyR
                 });
                 Ok(dsl::lit(s).into())
             },
-            _ => Ok(Expr::Literal(LiteralValue::try_from(av).unwrap()).into()),
+            _ => Ok(Expr::Literal(LiteralValue::from(av)).into()),
         }
     }
 }

py-polars/tests/unit/functions/test_lit.py

@@ -195,3 +195,11 @@ def test_lit_decimal_parametric(s: pl.Series) -> None:
 
     assert df.dtypes[0] == pl.Decimal(None, scale)
     assert result == value
+
+
+@pytest.mark.parametrize(
+    "item",
+    [{}, {"foo": 1}],
+)
+def test_lit_structs(item: Any) -> None:
+    assert pl.select(pl.lit(item)).to_dict(as_series=False) == {"literal": [item]}