feat(es/minifier): Ignore return value if a param of IIFE is not used (…

…#6115)

crates/swc/tests/tsc-references/emitDefaultParametersFunctionExpressionES6.2.minified.js

@@ -1,2 +1,2 @@
 //// [emitDefaultParametersFunctionExpressionES6.ts]
-!function(num, boo = !1, ...rest) {}(10);
+!function(num, boo = !1, ...rest) {}(0);

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

@@ -119,7 +119,7 @@ export var M = function(_superClass) {
         return _class_call_check(this, M), _this.prop = 12, _possible_constructor_return(_this);
     }
     return _inherits(M, null), _create_super(M), M;
-}(null);
+}(0);
 export var N = function(L) {
     "use strict";
     _inherits(N, L);
@@ -148,7 +148,7 @@ export var VariableBase = function(x) {
         return _class_call_check(this, VariableBase), _super.apply(this, arguments);
     }
     return VariableBase;
-}(null);
+}(0);
 export var HasStatics = function() {
     "use strict";
     function HasStatics() {

crates/swc/tests/tsc-references/literalTypes2.2.minified.js

@@ -21,4 +21,4 @@ var aa = [
 aa = function(a, x) {
     var result = a.slice();
     return result.push(1), result;
-}(aa, 1);
+}(aa, 0);

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

@@ -157,21 +157,6 @@ where
             Callee::Expr(e) => &mut **e,
         };
 
-        fn find_params(callee: &mut Expr) -> Option<Vec<&mut Pat>> {
-            match callee {
-                Expr::Arrow(callee) => Some(callee.params.iter_mut().collect()),
-                Expr::Fn(callee) => Some(
-                    callee
-                        .function
-                        .params
-                        .iter_mut()
-                        .map(|param| &mut param.pat)
-                        .collect(),
-                ),
-                _ => None,
-            }
-        }
-
         fn clean_params(callee: &mut Expr) {
             match callee {
                 Expr::Arrow(callee) => callee.params.retain(|p| !p.is_invalid()),
@@ -195,17 +180,6 @@ where
             }
         }
 
-        fn find_body(callee: &mut Expr) -> Option<Either<&mut BlockStmt, &mut Expr>> {
-            match callee {
-                Expr::Arrow(e) => match &mut e.body {
-                    BlockStmtOrExpr::BlockStmt(b) => Some(Either::Left(b)),
-                    BlockStmtOrExpr::Expr(b) => Some(Either::Right(&mut **b)),
-                },
-                Expr::Fn(e) => Some(Either::Left(e.function.body.as_mut().unwrap())),
-                _ => None,
-            }
-        }
-
         let params = find_params(callee);
         if let Some(mut params) = params {
             let mut vars = HashMap::default();
@@ -315,13 +289,106 @@ where
                     trace_op!("inline: Inlining arguments");
                     optimizer.inline_vars_in_node(body, vars);
                 }
-                _ => {}
+                _ => {
+                    unreachable!("find_body and find_params should match")
+                }
             }
         }
 
         clean_params(callee);
     }
 
+    /// If a parameter is not used, we can ignore return value of the
+    /// corresponding argument.
+    pub(super) fn ignore_unused_args_of_iife(&mut self, e: &mut CallExpr) {
+        if !self.options.unused {
+            return;
+        }
+
+        let callee = match &mut e.callee {
+            Callee::Super(_) | Callee::Import(_) => return,
+            Callee::Expr(e) => &mut **e,
+        };
+
+        match find_body(callee) {
+            Some(body) => match body {
+                Either::Left(body) => {
+                    if contains_arguments(body) {
+                        return;
+                    }
+                }
+                Either::Right(body) => {
+                    if contains_arguments(body) {
+                        return;
+                    }
+                }
+            },
+            None => return,
+        }
+
+        if let Expr::Fn(FnExpr {
+            ident: Some(ident), ..
+        }) = callee
+        {
+            if self
+                .data
+                .vars
+                .get(&ident.to_id())
+                .filter(|usage| usage.used_recursively)
+                .is_some()
+            {
+                return;
+            }
+        }
+
+        let mut removed = vec![];
+        let params = find_params(callee);
+        if let Some(mut params) = params {
+            // We check for parameter and argument
+            for (idx, param) in params.iter_mut().enumerate() {
+                if let Pat::Ident(param) = &mut **param {
+                    if let Some(usage) = self.data.vars.get(&param.to_id()) {
+                        if usage.ref_count == 0 {
+                            removed.push(idx);
+                        }
+                    }
+                }
+            }
+
+            if removed.is_empty() {
+                log_abort!("`removed` is empty");
+                return;
+            }
+        } else {
+            unreachable!("find_body and find_params should match")
+        }
+
+        for idx in removed {
+            if let Some(arg) = e.args.get_mut(idx) {
+                if arg.spread.is_some() {
+                    break;
+                }
+
+                // Optimize
+                let new = self.ignore_return_value(&mut arg.expr);
+
+                if let Some(new) = new {
+                    arg.expr = Box::new(new);
+                } else {
+                    // Use `0` if it's removed.
+                    arg.expr = Number {
+                        span: arg.expr.span(),
+                        value: 0.0,
+                        raw: None,
+                    }
+                    .into();
+                }
+            } else {
+                break;
+            }
+        }
+    }
+
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
     pub(super) fn inline_vars_in_node<N>(&mut self, n: &mut N, mut vars: FxHashMap<Id, Box<Expr>>)
     where
@@ -1014,3 +1081,28 @@ where
         }
     }
 }
+
+fn find_params(callee: &mut Expr) -> Option<Vec<&mut Pat>> {
+    match callee {
+        Expr::Arrow(callee) => Some(callee.params.iter_mut().collect()),
+        Expr::Fn(callee) => Some(
+            callee
+                .function
+                .params
+                .iter_mut()
+                .map(|param| &mut param.pat)
+                .collect(),
+        ),
+        _ => None,
+    }
+}
+fn find_body(callee: &mut Expr) -> Option<Either<&mut BlockStmt, &mut Expr>> {
+    match callee {
+        Expr::Arrow(e) => match &mut e.body {
+            BlockStmtOrExpr::BlockStmt(b) => Some(Either::Left(b)),
+            BlockStmtOrExpr::Expr(b) => Some(Either::Right(&mut **b)),
+        },
+        Expr::Fn(e) => Some(Either::Left(e.function.body.as_mut().unwrap())),
+        _ => None,
+    }
+}

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

@@ -623,7 +623,8 @@ where
                     "ignore_return_value: Dropping unused expr: {}",
                     dump(&*e, false)
                 );
-                self.changed = true;
+                // We don't need to run this again
+                // self.changed = true;
                 return None;
             }
 
@@ -1575,6 +1576,7 @@ where
             e.args.visit_mut_with(&mut *self.with_ctx(ctx));
         }
 
+        self.ignore_unused_args_of_iife(e);
         self.inline_args_of_iife(e);
     }
 

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

@@ -5959,7 +5959,7 @@
                     state.z2 = el.z2 + (null != z2EmphasisLift ? z2EmphasisLift : 10);
                 }
                 return state;
-            }(this, stateName, targetStates, state1);
+            }(this, 0, targetStates, state1);
             if ('blur' === stateName) return state = state1, hasBlur = indexOf(this.currentStates, stateName) >= 0, currentOpacity = this.style.opacity, fromState = hasBlur ? null : function(el, props, toStateName, defaultValue) {
                 for(var style = el.style, fromState = {}, i = 0; i < props.length; i++){
                     var propName = props[i], val = style[propName];
@@ -5984,7 +5984,7 @@
                     state.z2 = el.z2 + (null != z2SelectLift ? z2SelectLift : 9);
                 }
                 return state;
-            }(this, stateName, state1);
+            }(this, 0, state1);
         }
         return state1;
     }
@@ -15449,7 +15449,7 @@
                             for(var i = 0; i < lastLevelTicks.length - 1; i++){
                                 var approxInterval1, approxInterval2, approxInterval3, startTick = lastLevelTicks[i].value, endTick = lastLevelTicks[i + 1].value;
                                 if (startTick !== endTick) {
-                                    var interval = void 0, getterName = void 0, setterName = void 0, isDate = !1;
+                                    var interval = void 0, getterName = void 0, setterName = void 0;
                                     switch(unitName){
                                         case 'year':
                                             interval = Math.max(1, Math.round(approxInterval / 86400000 / 365)), getterName = fullYearGetterName(isUTC), setterName = isUTC ? 'setUTCFullYear' : 'setFullYear';
@@ -15462,7 +15462,7 @@
                                         case 'week':
                                         case 'half-week':
                                         case 'day':
-                                            approxInterval2 = approxInterval, interval = (approxInterval2 /= 86400000) > 16 ? 16 : approxInterval2 > 7.5 ? 7 : approxInterval2 > 3.5 ? 4 : approxInterval2 > 1.5 ? 2 : 1, getterName = dateGetterName(isUTC), setterName = dateSetterName(isUTC), isDate = !0;
+                                            approxInterval2 = approxInterval, interval = (approxInterval2 /= 86400000) > 16 ? 16 : approxInterval2 > 7.5 ? 7 : approxInterval2 > 3.5 ? 4 : approxInterval2 > 1.5 ? 2 : 1, getterName = dateGetterName(isUTC), setterName = dateSetterName(isUTC);
                                             break;
                                         case 'half-day':
                                         case 'quarter-day':
@@ -15486,7 +15486,7 @@
                                             value: dateTime,
                                             notAdd: !0
                                         });
-                                    })(interval, startTick, endTick, getterName, setterName, isDate, newAddedTicks), 'year' === unitName && levelTicks.length > 1 && 0 === i && levelTicks.unshift({
+                                    })(interval, startTick, endTick, getterName, setterName, 0, newAddedTicks), 'year' === unitName && levelTicks.length > 1 && 0 === i && levelTicks.unshift({
                                         value: levelTicks[0].value - interval
                                     });
                                 }
@@ -23738,7 +23738,7 @@
                                     return inner$8(mapping).drColorMappingBy = colorMappingBy, mapping;
                                 }
                             }
-                        }(node, nodeModel, nodeLayout, nodeItemStyleModel, visuals1, viewChildren);
+                        }(0, nodeModel, nodeLayout, 0, visuals1, viewChildren);
                         each(viewChildren, function(child, index) {
                             if (child.depth >= viewRootAncestors.length || child === viewRootAncestors[child.depth]) {
                                 var childVisual = function(nodeModel, visuals, child, index, mapping, seriesModel) {
@@ -27474,7 +27474,7 @@
                             depth: maxDepth
                         }, !0);
                     });
-                }(nodes, nodeAlign, orient, maxDepth), kx = 'vertical' === orient ? (height - nodeWidth) / maxDepth : (width - nodeWidth) / maxDepth, each(nodes, function(node) {
+                }(nodes, nodeAlign, 0, maxDepth), kx = 'vertical' === orient ? (height - nodeWidth) / maxDepth : (width - nodeWidth) / maxDepth, each(nodes, function(node) {
                     var nodeDepth = node.getLayout().depth * kx;
                     'vertical' === orient ? node.setLayout({
                         y: nodeDepth
@@ -29254,7 +29254,7 @@
             barRectShape[valueDim.wh] = pxSign * Math.max(Math.abs(layout[valueDim.wh]), Math.abs(pathPosition[valueDim.index] + sizeFix)), barRectShape[categoryDim.wh] = layout[categoryDim.wh];
             var clipShape = outputSymbolMeta.clipShape = {};
             clipShape[categoryDim.xy] = -layout[categoryDim.xy], clipShape[categoryDim.wh] = opt.ecSize[categoryDim.wh], clipShape[valueDim.xy] = 0, clipShape[valueDim.wh] = layout[valueDim.wh];
-        }(itemModel, symbolSize1, layout, symbolRepeat, symbolClip, symbolOffset, symbolPosition, symbolMeta.valueLineWidth, symbolMeta.boundingLength, symbolMeta.repeatCutLength, opt, symbolMeta), symbolMeta;
+        }(itemModel, symbolSize1, layout, symbolRepeat, 0, symbolOffset, symbolPosition, symbolMeta.valueLineWidth, symbolMeta.boundingLength, symbolMeta.repeatCutLength, opt, symbolMeta), symbolMeta;
     }
     function convertToCoordOnAxis(axis, value) {
         return axis.toGlobalCoord(axis.dataToCoord(axis.scale.parse(value)));
@@ -32125,10 +32125,7 @@
                 var elStyle = buildElStyle(axisPointerModel), pointerOption = pointerShapeBuilder$1[axisPointerType](axis, polar, coordValue, otherExtent);
                 pointerOption.style = elStyle, elOption.graphicKey = pointerOption.type, elOption.pointer = pointerOption;
             }
-            var labelMargin = axisPointerModel.get([
-                'label',
-                'margin'
-            ]), labelPos = function(value, axisModel, axisPointerModel, polar, labelMargin) {
+            var labelPos = function(value, axisModel, axisPointerModel, polar, labelMargin) {
                 var position, align, verticalAlign, axis = axisModel.axis, coord = axis.dataToCoord(value), axisAngle = polar.getAngleAxis().getExtent()[0];
                 axisAngle = axisAngle / 180 * Math.PI;
                 var radiusExtent = polar.getRadiusAxis().getExtent();
@@ -32157,7 +32154,10 @@
                     align: align,
                     verticalAlign: verticalAlign
                 };
-            }(value, axisModel, axisPointerModel, polar, labelMargin);
+            }(value, axisModel, 0, polar, axisPointerModel.get([
+                'label',
+                'margin'
+            ]));
             buildLabelElOption(elOption, axisModel, axisPointerModel, api, labelPos);
         }, PolarAxisPointer;
     }(BaseAxisPointer), pointerShapeBuilder$1 = {

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

@@ -22575,7 +22575,7 @@
                                     duration: exit
                                 } : {
                                     delay: exit
-                                }), child, data, exitingNodes, function() {
+                                }), 0, data, exitingNodes, function() {
                                     setState({
                                         nodesWillExit: !1
                                     });
@@ -22615,7 +22615,7 @@
                                         animate: animate,
                                         data: data
                                     };
-                                }(animate1, child, data, enteringNodes, function() {
+                                }(animate1, 0, data, enteringNodes, function() {
                                     setState({
                                         nodesShouldEnter: !0
                                     });
@@ -22664,7 +22664,7 @@
                                     }),
                                     clipWidth: 0
                                 };
-                            }(animate2, child, data, function() {
+                            }(animate2, 0, data, function() {
                                 setState({
                                     nodesDoneLoad: !0
                                 });

crates/swc_ecma_minifier/tests/fixture/issues/firebase-core/1/output.js

@@ -1871,7 +1871,7 @@
                                 };
                                 img.complete ? handleLoad() : img.onload = handleLoad;
                             }
-                        }(img, srcString, layout, placeholder, onLoadingComplete);
+                        }(img, srcString, 0, placeholder, onLoadingComplete);
                     },
                     style: _objectSpread({}, imgStyle, blurStyle)
                 })), _react.default.createElement("noscript", null, _react.default.createElement("img", Object.assign({}, rest, generateImgAttrs({

crates/swc_ecma_minifier/tests/fixture/issues/quagga2/1.4.2/1/output.js

@@ -6854,7 +6854,7 @@
                                         if ("Exif" !== function(buffer, start, length) {
                                             for(var outstr = "", n = start; n < start + 4; n++)outstr += String.fromCharCode(buffer.getUint8(n));
                                             return outstr;
-                                        }(file, start, 4)) return !1;
+                                        }(file, start, 0)) return !1;
                                         var bigEnd, tiffOffset = start + 6;
                                         if (0x4949 === file.getUint16(tiffOffset)) bigEnd = !1;
                                         else {
@@ -6869,10 +6869,10 @@
                                                 tag && (tags[tag] = function(file, entryOffset, tiffStart, dirStart, bigEnd) {
                                                     var type = file.getUint16(entryOffset + 2, !bigEnd), numValues = file.getUint32(entryOffset + 4, !bigEnd);
                                                     return 3 === type && 1 === numValues ? file.getUint16(entryOffset + 8, !bigEnd) : null;
-                                                }(file, entryOffset, tiffStart, dirStart, bigEnd));
+                                                }(file, entryOffset, 0, 0, bigEnd));
                                             }
                                             return tags;
-                                        }(file, tiffOffset, tiffOffset + firstIFDOffset, exifTags, bigEnd);
+                                        }(file, 0, tiffOffset + firstIFDOffset, exifTags, bigEnd);
                                     }(dataView, offset + 4, exifTags);
                                     offset += 2 + dataView.getUint16(offset + 2);
                                 }

crates/swc_ecma_minifier/tests/fixture/issues/react-countup/1/output.js

@@ -262,7 +262,7 @@
                                 };
                                 img.complete ? handleLoad() : img.onload = handleLoad;
                             }
-                        }(img, srcString, layout, placeholder, onLoadingComplete);
+                        }(img, srcString, 0, placeholder, onLoadingComplete);
                     },
                     style: _objectSpread({}, imgStyle, blurStyle)
                 })), _react.default.createElement("noscript", null, _react.default.createElement("img", Object.assign({}, rest, generateImgAttrs({

crates/swc_ecma_minifier/tests/fixture/next/33265/static/chunks/pages/index-cb36c1bf7f830e3c/output.js

@@ -4607,7 +4607,7 @@
                             return bestPosition || specifiedPosition;
                         }(boxPosition, axis);
                         styleBox.move(bestPosition.toCSSCompatValues(containerBox));
-                    }(window1, styleBox, containerBox, boxPositions), cue.displayState = styleBox.div, boxPositions.push(BoxPosition.getSimpleBoxPosition(styleBox));
+                    }(0, styleBox, containerBox, boxPositions), cue.displayState = styleBox.div, boxPositions.push(BoxPosition.getSimpleBoxPosition(styleBox));
                 }();
             }, WebVTT1.Parser = function(window1, vttjs, decoder) {
                 decoder || (decoder = vttjs, vttjs = {}), vttjs || (vttjs = {}), this.window = window1, this.vttjs = vttjs, this.state = "INITIAL", this.buffer = "", this.decoder = decoder || new TextDecoder("utf8"), this.regionList = [];