default arg fns are infallible

src/builtin/color/hsl.rs

@@ -184,7 +184,7 @@ fn inner_hsl(name: &'static str, mut args: CallArgs, parser: &mut Parser<'_>) ->
             3,
             "alpha",
             Value::Dimension(Number::one(), Unit::None),
-        )? {
+        ) {
             Value::Dimension(n, Unit::None) => n,
             Value::Dimension(n, Unit::Percent) => n / Number::from(100),
             v @ Value::Dimension(..) => {
@@ -469,7 +469,7 @@ fn invert(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
         1,
         "weight",
         Value::Dimension(Number::from(100), Unit::Percent),
-    )? {
+    ) {
         Value::Dimension(n, u) => bound!(args, "weight", n, u, 0, 100) / Number::from(100),
         v => {
             return Err((

src/builtin/color/other.rs

@@ -14,7 +14,7 @@ use crate::{
 
 macro_rules! opt_rgba {
     ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal, $parser:ident) => {
-        let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null)? {
+        let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null) {
             Value::Dimension(n, u) => Some(bound!($args, $arg, n, u, $low, $high)),
             Value::Null => None,
             v => {
@@ -34,7 +34,7 @@ macro_rules! opt_rgba {
 
 macro_rules! opt_hsl {
     ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal, $parser:ident) => {
-        let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null)? {
+        let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null) {
             Value::Dimension(n, u) => {
                 Some(bound!($args, $arg, n, u, $low, $high) / Number::from(100))
             }
@@ -88,7 +88,7 @@ fn change_color(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value
         ))));
     }
 
-    let hue = match parser.default_named_arg(&mut args, "hue", Value::Null)? {
+    let hue = match parser.default_named_arg(&mut args, "hue", Value::Null) {
         Value::Dimension(n, _) => Some(n),
         Value::Null => None,
         v => {
@@ -147,7 +147,7 @@ fn adjust_color(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value
         ))));
     }
 
-    let hue = match parser.default_named_arg(&mut args, "hue", Value::Null)? {
+    let hue = match parser.default_named_arg(&mut args, "hue", Value::Null) {
         Value::Dimension(n, _) => Some(n),
         Value::Null => None,
         v => {
@@ -205,7 +205,7 @@ fn scale_color(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value>
 
     macro_rules! opt_scale_arg {
         ($args:ident, $name:ident, $arg:literal, $low:literal, $high:literal, $parser:ident) => {
-            let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null)? {
+            let $name = match $parser.default_named_arg(&mut $args, $arg, Value::Null) {
                 Value::Dimension(n, Unit::Percent) => {
                     Some(bound!($args, $arg, n, Unit::Percent, $low, $high) / Number::from(100))
                 }

src/builtin/color/rgb.rs

@@ -305,7 +305,7 @@ fn inner_rgb(name: &'static str, mut args: CallArgs, parser: &mut Parser<'_>) ->
             3,
             "alpha",
             Value::Dimension(Number::one(), Unit::None),
-        )? {
+        ) {
             Value::Dimension(n, Unit::None) => n,
             Value::Dimension(n, Unit::Percent) => n / Number::from(100),
             v @ Value::Dimension(..) => {
@@ -416,7 +416,7 @@ fn mix(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
         2,
         "weight",
         Value::Dimension(Number::from(50), Unit::None),
-    )? {
+    ) {
         Value::Dimension(n, u) => bound!(args, "weight", n, u, 0, 100) / Number::from(100),
         v => {
             return Err((

src/builtin/list.rs

@@ -131,7 +131,7 @@ fn append(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
         2,
         "separator",
         Value::String("auto".to_owned(), QuoteKind::None),
-    )? {
+    ) {
         Value::String(s, ..) => match s.as_str() {
             "auto" => sep,
             "comma" => ListSeparator::Comma,
@@ -178,7 +178,7 @@ fn join(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
         2,
         "separator",
         Value::String("auto".to_owned(), QuoteKind::None),
-    )? {
+    ) {
         Value::String(s, ..) => match s.as_str() {
             "auto" => {
                 if list1.is_empty() || (list1.len() == 1 && sep1 == ListSeparator::Space) {
@@ -214,7 +214,7 @@ fn join(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
         3,
         "bracketed",
         Value::String("auto".to_owned(), QuoteKind::None),
-    )? {
+    ) {
         Value::String(s, ..) => match s.as_str() {
             "auto" => brackets,
             _ => Brackets::Bracketed,

src/builtin/math.rs

@@ -138,7 +138,7 @@ fn comparable(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value>
 #[cfg(feature = "random")]
 fn random(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
     args.max_args(1)?;
-    let limit = match parser.default_arg(&mut args, 0, "limit", Value::Null)? {
+    let limit = match parser.default_arg(&mut args, 0, "limit", Value::Null) {
         Value::Dimension(n, _) => n,
         Value::Null => {
             let mut rng = rand::thread_rng();

src/builtin/meta.rs

@@ -176,9 +176,9 @@ fn get_function(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value
         }
     };
     let css = parser
-        .default_arg(&mut args, 1, "css", Value::False)?
+        .default_arg(&mut args, 1, "css", Value::False)
         .is_true(args.span())?;
-    let module = match parser.default_arg(&mut args, 2, "module", Value::Null)? {
+    let module = match parser.default_arg(&mut args, 2, "module", Value::Null) {
         Value::String(s, ..) => Some(s),
         Value::Null => None,
         v => {
@@ -246,10 +246,7 @@ fn content_exists(args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value>
             .into());
     }
     Ok(Value::bool(
-        parser
+        parser.content.last().map_or(false, |c| c.content.is_some()),
-            .content
-            .last()
-            .map_or(false, |c| c.content.is_some())
     ))
 }
 

src/builtin/string.rs

@@ -148,7 +148,7 @@ fn str_slice(mut args: CallArgs, parser: &mut Parser<'_>) -> SassResult<Value> {
                 .into())
         }
     };
-    let mut end = match parser.default_arg(&mut args, 2, "end-at", Value::Null)? {
+    let mut end = match parser.default_arg(&mut args, 2, "end-at", Value::Null) {
         Value::Dimension(n, Unit::None) if n.is_decimal() => {
             return Err((format!("{} is not an int.", n), args.span()).into())
         }

src/parse/args.rs

@@ -237,11 +237,11 @@ impl<'a> Parser<'a> {
         position: usize,
         name: &'static str,
         default: Value,
-    ) -> SassResult<Value> {
+    ) -> Value {
-        Ok(match args.get(position, name) {
+        match args.get(position, name) {
             Some(val) => val.node,
             None => default,
-        })
+        }
     }
 
     pub fn positional_arg(
@@ -262,11 +262,11 @@ impl<'a> Parser<'a> {
         args: &mut CallArgs,
         name: &'static str,
         default: Value,
-    ) -> SassResult<Value> {
+    ) -> Value {
-        Ok(match args.get_named(name) {
+        match args.get_named(name) {
             Some(val) => val.node,
             None => default,
-        })
+        }
     }
 
     pub fn variadic_args(&mut self, args: CallArgs) -> SassResult<Vec<Spanned<Value>>> {