fix(minifier): drop unused call args for known function bindings

crates/swc/tests/tsc-references/callbackTagVariadicType.2.minified.js

@@ -2,4 +2,4 @@
 export var x = function() {
     return 1;
 };
-x('a', 'b');
+x();

crates/swc/tests/tsc-references/taggedTemplateStringsWithOverloadResolution3.2.minified.js

@@ -218,5 +218,5 @@ function _templateObject21() {
 }
 function fn2() {}
 _templateObject(), _templateObject1();
-var d1 = fn2(_templateObject2(), 0, void 0), d2 = fn2(_templateObject3(), 0, void 0);
+var d1 = fn2(_templateObject2()), d2 = fn2(_templateObject3());
 d1.foo(), d2(), _templateObject4(), _templateObject5(), _templateObject6(), _templateObject7(), _templateObject8(), _templateObject9(), _templateObject10(), _templateObject11(), _templateObject12(), _templateObject13(), _templateObject14(), _templateObject15(), _templateObject16(), _templateObject17(), _templateObject18(), _templateObject19(), _templateObject20(), _templateObject21();

crates/swc_ecma_minifier/src/compress/optimize/call_args.rs

@@ -0,0 +1,67 @@
+use swc_ecma_ast::*;
+
+use super::Optimizer;
+use crate::program_data::VarUsageInfoFlags;
+
+impl Optimizer<'_> {
+    /// Drop trailing call arguments that are guaranteed to be unused by a
+    /// known function binding.
+    pub(super) fn drop_unused_args_of_known_fn_call(&mut self, e: &mut CallExpr) {
+        if !self.options.unused && !self.options.reduce_vars {
+            return;
+        }
+
+        let callee = match &e.callee {
+            Callee::Super(_) | Callee::Import(_) => return,
+            Callee::Expr(callee) => match &**callee {
+                Expr::Ident(callee) => callee,
+                _ => return,
+            },
+            #[cfg(swc_ast_unknown)]
+            _ => panic!("unable to access unknown nodes"),
+        };
+
+        let Some(usage) = self.data.vars.get(&callee.to_id()) else {
+            return;
+        };
+        if usage.flags.contains(VarUsageInfoFlags::REASSIGNED) {
+            return;
+        }
+
+        let Some(metadata) = self.functions.get(&callee.to_id()) else {
+            return;
+        };
+
+        if metadata.has_rest || metadata.uses_arguments {
+            return;
+        }
+
+        if e.args.len() <= metadata.param_count {
+            return;
+        }
+
+        if e.args.iter().any(|arg| arg.spread.is_some()) {
+            return;
+        }
+
+        let mut removed = false;
+
+        for idx in (metadata.param_count..e.args.len()).rev() {
+            if let Some(arg) = e.args.get_mut(idx) {
+                let new = self.ignore_return_value(&mut arg.expr);
+
+                if let Some(new) = new {
+                    arg.expr = Box::new(new);
+                } else {
+                    e.args.remove(idx);
+                    removed = true;
+                }
+            }
+        }
+
+        if removed {
+            self.changed = true;
+            report_change!("unused: Dropped trailing unused call arguments");
+        }
+    }
+}

crates/swc_ecma_minifier/src/compress/optimize/mod.rs

@@ -38,6 +38,7 @@ use crate::{
 
 mod arguments;
 mod bools;
+mod call_args;
 mod conditionals;
 mod dead_code;
 mod drop_console;
@@ -336,21 +337,40 @@ impl Repeated for Optimizer<'_> {
 #[derive(Debug, Clone, Copy)]
 struct FnMetadata {
     len: usize,
+    param_count: usize,
+    has_rest: bool,
+    uses_arguments: bool,
 }
 
-impl From<&Function> for FnMetadata {
-    fn from(f: &Function) -> Self {
+fn function_length_from_params<'a>(params: impl IntoIterator<Item = &'a Pat>) -> usize {
+    params
+        .into_iter()
+        .filter(|p| matches!(p, Pat::Ident(..) | Pat::Array(..) | Pat::Object(..)))
+        .count()
+}
+
+impl Optimizer<'_> {
+    fn fn_metadata_of_function(&self, f: &Function) -> FnMetadata {
         FnMetadata {
-            len: f
-                .params
-                .iter()
-                .filter(|p| matches!(&p.pat, Pat::Ident(..) | Pat::Array(..) | Pat::Object(..)))
-                .count(),
+            len: function_length_from_params(f.params.iter().map(|p| &p.pat)),
+            param_count: f.params.len(),
+            has_rest: f.params.iter().any(|p| p.pat.is_rest()),
+            uses_arguments: self
+                .data
+                .get_scope(f.ctxt)
+                .is_some_and(|scope| scope.contains(ScopeData::USED_ARGUMENTS)),
+        }
+    }
+
+    fn fn_metadata_of_arrow(&self, a: &ArrowExpr) -> FnMetadata {
+        FnMetadata {
+            len: function_length_from_params(a.params.iter()),
+            param_count: a.params.len(),
+            has_rest: a.params.iter().any(Pat::is_rest),
+            uses_arguments: false,
         }
     }
-}
 
-impl Optimizer<'_> {
     fn may_remove_ident(&self, id: &Ident) -> bool {
         if self
             .data
@@ -1711,6 +1731,7 @@ impl VisitMut for Optimizer<'_> {
         self.ignore_unused_args_of_iife(e);
         self.inline_args_of_iife(e);
         self.drop_arguments_of_symbol_call(e);
+        self.drop_unused_args_of_known_fn_call(e);
 
         // Try to replace static method call with alias (after other transformations)
         if let Callee::Expr(callee) = &mut e.callee {
@@ -2135,9 +2156,8 @@ impl VisitMut for Optimizer<'_> {
         )
         .entered();
 
-        self.functions
-            .entry(f.ident.to_id())
-            .or_insert_with(|| FnMetadata::from(&*f.function));
+        let metadata = self.fn_metadata_of_function(&f.function);
+        self.functions.entry(f.ident.to_id()).or_insert(metadata);
 
         self.drop_unused_params(&mut f.function.params);
 
@@ -2154,9 +2174,8 @@ impl VisitMut for Optimizer<'_> {
     #[cfg_attr(feature = "debug", tracing::instrument(level = "debug", skip_all))]
     fn visit_mut_fn_expr(&mut self, e: &mut FnExpr) {
         if let Some(ident) = &e.ident {
-            self.functions
-                .entry(ident.to_id())
-                .or_insert_with(|| FnMetadata::from(&*e.function));
+            let metadata = self.fn_metadata_of_function(&e.function);
+            self.functions.entry(ident.to_id()).or_insert(metadata);
         }
 
         if !self.options.keep_fnames {
@@ -3016,6 +3035,23 @@ impl VisitMut for Optimizer<'_> {
 
         debug_assert_valid(&var.init);
 
+        if let VarDeclarator {
+            name: Pat::Ident(id),
+            init: Some(init),
+            ..
+        } = var
+        {
+            let metadata = match &**init {
+                Expr::Fn(FnExpr { function, .. }) => Some(self.fn_metadata_of_function(function)),
+                Expr::Arrow(arrow) => Some(self.fn_metadata_of_arrow(arrow)),
+                _ => None,
+            };
+
+            if let Some(metadata) = metadata {
+                self.functions.entry(id.id.to_id()).or_insert(metadata);
+            }
+        }
+
         if let VarDeclarator {
             name: Pat::Ident(id),
             init: Some(init),

crates/swc_ecma_minifier/tests/benches-full/victory.js

@@ -30598,7 +30598,7 @@
                     scale: scale,
                     axisType: axisType,
                     text: text
-                }).tickStyle, axisAngle = "radial" === axisType ? getAxisAngle(props, scale) : void 0, tickPadding = tickStyle.padding || tickStyle.size || 0, padAngle = victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(90 - axisAngle), tickAngle = "angular" === axisType ? scale(tickValue) : victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(-1 * axisAngle), tickRadius = "angular" === axisType ? radius : scale(tickValue);
+                }).tickStyle, axisAngle = "radial" === axisType ? getAxisAngle(props) : void 0, tickPadding = tickStyle.padding || tickStyle.size || 0, padAngle = victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(90 - axisAngle), tickAngle = "angular" === axisType ? scale(tickValue) : victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(-1 * axisAngle), tickRadius = "angular" === axisType ? radius : scale(tickValue);
                 return "angular" === axisType ? {
                     index: index,
                     datum: tick,
@@ -30627,7 +30627,7 @@
                     radius: radius,
                     scale: scale,
                     axisType: axisType
-                }).labelStyle, tickLabelComponent = props.tickLabelComponent, labelPlacement = tickLabelComponent.props && tickLabelComponent.props.labelPlacement ? tickLabelComponent.props.labelPlacement : props.labelPlacement, tickPadding = labelStyle.padding || 0, axisAngle = "radial" === axisType ? getAxisAngle(props, scale) : void 0, labelAngle = "angular" === axisType ? victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.radiansToDegrees(scale(tickValue)) : axisAngle + 0, textAngle = void 0 === labelStyle.angle ? victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getPolarAngle(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
+                }).labelStyle, tickLabelComponent = props.tickLabelComponent, labelPlacement = tickLabelComponent.props && tickLabelComponent.props.labelPlacement ? tickLabelComponent.props.labelPlacement : props.labelPlacement, tickPadding = labelStyle.padding || 0, axisAngle = "radial" === axisType ? getAxisAngle(props) : void 0, labelAngle = "angular" === axisType ? victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.radiansToDegrees(scale(tickValue)) : axisAngle + 0, textAngle = void 0 === labelStyle.angle ? victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getPolarAngle(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
                     labelPlacement: labelPlacement
                 }), labelAngle) : labelStyle.angle, labelRadius = "angular" === axisType ? radius + tickPadding : scale(tickValue), textAnchor = labelStyle.textAnchor || victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getPolarTextAnchor(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
                     labelPlacement: labelPlacement
@@ -30673,9 +30673,9 @@
                     endAngle: endAngle
                 };
             }, getAxisLabelProps = function(props, calculatedValues) {
-                var axisType = calculatedValues.axisType, radius = calculatedValues.radius, style = calculatedValues.style, scale = calculatedValues.scale, origin = calculatedValues.origin, axisLabelComponent = props.axisLabelComponent;
+                var axisType = calculatedValues.axisType, radius = calculatedValues.radius, style = calculatedValues.style, origin = (calculatedValues.scale, calculatedValues.origin), axisLabelComponent = props.axisLabelComponent;
                 if ("radial" !== axisType) return {};
-                var labelPlacement = axisLabelComponent.props && axisLabelComponent.props.labelPlacement ? axisLabelComponent.props.labelPlacement : props.labelPlacement, labelStyle = style && style.axisLabel || {}, axisAngle = "radial" === axisType ? getAxisAngle(props, scale) : void 0, textAngle = void 0 === labelStyle.angle ? victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getPolarAngle(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
+                var labelPlacement = axisLabelComponent.props && axisLabelComponent.props.labelPlacement ? axisLabelComponent.props.labelPlacement : props.labelPlacement, labelStyle = style && style.axisLabel || {}, axisAngle = "radial" === axisType ? getAxisAngle(props) : void 0, textAngle = void 0 === labelStyle.angle ? victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getPolarAngle(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
                     labelPlacement: labelPlacement
                 }), axisAngle) : labelStyle.angle, labelRadius = radius + (labelStyle.padding || 0), textAnchor = labelStyle.textAnchor || victory_core__WEBPACK_IMPORTED_MODULE_3__.LabelHelpers.getTextPolarAnchor(lodash_assign__WEBPACK_IMPORTED_MODULE_2___default()({}, props, {
                     labelPlacement: labelPlacement
@@ -30692,7 +30692,7 @@
                     y: getPosition(labelRadius, victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(axisAngle), "y") + origin.y
                 };
             }, getAxisProps = function(modifiedProps, calculatedValues) {
-                var style = calculatedValues.style, axisType = calculatedValues.axisType, radius = calculatedValues.radius, scale = calculatedValues.scale, origin = calculatedValues.origin, startAngle = modifiedProps.startAngle, endAngle = modifiedProps.endAngle, _modifiedProps$innerR = modifiedProps.innerRadius, innerRadius = void 0 === _modifiedProps$innerR ? 0 : _modifiedProps$innerR, axisAngle = "radial" === axisType ? victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(getAxisAngle(modifiedProps, scale)) : void 0;
+                var style = calculatedValues.style, axisType = calculatedValues.axisType, radius = calculatedValues.radius, origin = (calculatedValues.scale, calculatedValues.origin), startAngle = modifiedProps.startAngle, endAngle = modifiedProps.endAngle, _modifiedProps$innerR = modifiedProps.innerRadius, innerRadius = void 0 === _modifiedProps$innerR ? 0 : _modifiedProps$innerR, axisAngle = "radial" === axisType ? victory_core__WEBPACK_IMPORTED_MODULE_3__.Helpers.degreesToRadians(getAxisAngle(modifiedProps)) : void 0;
                 return "radial" === axisType ? {
                     style: style.axis,
                     x1: getPosition(innerRadius, axisAngle, "x") + origin.x,

crates/swc_ecma_minifier/tests/fixture/issues/2257/full/output.js

@@ -1704,7 +1704,7 @@
             };
         } // CONCATENATED MODULE: ./node_modules/_@swc_helpers@0.2.13@@swc/helpers/src/_sliced_to_array.js
         function _slicedToArray(arr, i) {
-            return _arrayWithHoles(arr) || _iterableToArray(arr, i) || _nonIterableRest();
+            return _arrayWithHoles(arr) || _iterableToArray(arr) || _nonIterableRest();
         } // CONCATENATED MODULE: ./node_modules/_@swc_helpers@0.2.13@@swc/helpers/src/_sliced_to_array_loose.js
         function _slicedToArrayLoose(arr, i) {
             return _arrayWithHoles(arr) || _iterableToArrayLimitLoose(arr, i) || _nonIterableRest();

crates/swc_ecma_minifier/tests/fixture/issues/7784/3/output.js

@@ -2,5 +2,5 @@ export function f(i, e, cmp) {
     function g() {
         return i++, e || 0;
     }
-    return e = g(e), cmp(i, e) && console.log(e), g;
+    return e = g(), cmp(i, e) && console.log(e), g;
 }

crates/swc_ecma_minifier/tests/fixture/next/33265/static/chunks/d6e1aeb5-38a8d7ae57119c23/output.js

@@ -11097,7 +11097,7 @@
                 try {
                     var muted = Html5.TEST_VID.muted; // in some versions of iOS muted property doesn't always
                     return(// work, so we want to set both property and attribute
-                    Html5.TEST_VID.muted = !muted, Html5.TEST_VID.muted ? setAttribute(Html5.TEST_VID, "muted", "muted") : removeAttribute(Html5.TEST_VID, "muted", "muted"), muted !== Html5.TEST_VID.muted);
+                    Html5.TEST_VID.muted = !muted, Html5.TEST_VID.muted ? setAttribute(Html5.TEST_VID, "muted", "muted") : removeAttribute(Html5.TEST_VID, "muted"), muted !== Html5.TEST_VID.muted);
                 } catch (e) {
                     return !1;
                 }

crates/swc_ecma_minifier/tests/fixture/next/47005/output.js

@@ -121,17 +121,12 @@
                     ...k.platform,
                     _c: E
                 };
-                return V(m, S, {
-                    ...k,
-                    platform: R
-                });
+                return V();
             };
             var er = async ({ elementReference: m = null, tooltipReference: S = null, tooltipArrowReference: h = null, place: E = "top", offset: k = 10, strategy: R = "absolute", middlewares: A = [
                 X(Number(k)),
                 W(),
-                Y({
-                    padding: 5
-                })
+                Y()
             ] })=>{
                 if (!m) return {
                     tooltipStyles: {},
@@ -213,7 +208,7 @@
                     };
                     eo(S), V.current = S;
                 }, ei = (m)=>{
-                    ee(m), y;
+                    ee(), y;
                 }, ea = (S)=>{
                     var h;
                     [
@@ -222,7 +217,7 @@
                     ].some((m)=>null == m ? void 0 : m.contains(S.target)) || null != (h = m.current) && h.contains(S.target) || Z(!1);
                 }, eu = (m)=>{
                     "Escape" === m.key && Z(!1);
-                }, es = I(ee, 50), ec = I(et, 50);
+                }, es = I(), ec = I();
                 (0, A.useEffect)(()=>{
                     var S, h;
                     let E = new Set(W);