swc-project · kdy1 · Apr 21, 2022 · Apr 6, 2022 · Apr 6, 2022 · Apr 6, 2022
@@ -11,7 +11,6 @@ const reducer = (op, args)=>{
             break;
         case "concat":
             console.log(args.firstArr.concat(args.secondArr));
-            break;
     }
 };
 reducer("add", {

@@ -12,7 +12,6 @@ var reducer = function(op, args) {
             break;
         case "concat":
             console.log(args.firstArr.concat(args.secondArr));
-            break;
     }
 };
 reducer("add", {

@@ -77,7 +77,6 @@ var TypeScript;
                     context.skipNextFuncDeclForClass ? context.skipNextFuncDeclForClass = !1 : (context.scopeGetter = function() {
                         return funcDecl.isConstructor && hasFlag(funcDecl.fncFlags, FncFlags.ClassMethod) && ast.type && ast.type.enclosingType ? ast.type.enclosingType.constructorScope : funcDecl.scopeType ? funcDecl.scopeType.containedScope : funcDecl.type ? funcDecl.type.containedScope : null;
                     }, context.scopeStartAST = ast);
-                    break;
             }
             walker.options.goChildren = !0;
         } else walker.options.goChildren = !1;

@@ -42,7 +42,6 @@ import * as swcHelpers from "@swc/helpers";
                     context.skipNextFuncDeclForClass ? context.skipNextFuncDeclForClass = !1 : (context.scopeGetter = function() {
                         return funcDecl.isConstructor && hasFlag(funcDecl.fncFlags, FncFlags.ClassMethod) && ast.type && ast.type.enclosingType ? ast.type.enclosingType.constructorScope : funcDecl.scopeType ? funcDecl.scopeType.containedScope : funcDecl.type ? funcDecl.type.containedScope : null;
                     }, context.scopeStartAST = ast);
-                    break;
             }
             walker.options.goChildren = !0;
         } else walker.options.goChildren = !1;

@@ -246,7 +246,6 @@ var Formatting;
                         break;
                     case AuthorTokenKind.atkLBrack:
                         updateStartOffset = node.AuthorNode.Details.Kind == AuthorParseNodeKind.apnkArray;
-                        break;
                 }
                 updateStartOffset && ParseNodeExtensions.SetNodeSpan(node, token.Span.startPosition(), node.AuthorNode.Details.EndOffset);
             }

@@ -219,7 +219,6 @@ import * as swcHelpers from "@swc/helpers";
                         break;
                     case AuthorTokenKind.atkLBrack:
                         updateStartOffset = node.AuthorNode.Details.Kind == AuthorParseNodeKind.apnkArray;
-                        break;
                 }
                 updateStartOffset && ParseNodeExtensions.SetNodeSpan(node, token.Span.startPosition(), node.AuthorNode.Details.EndOffset);
             }

@@ -5,5 +5,4 @@ switch(foo){
         break;
     default:
         foo = foo[0];
-        break;
 }
@@ -5,5 +5,4 @@ switch(foo){
         break;
     default:
         foo = foo[0];
-        break;
 }
@@ -0,0 +1,6 @@
+'';
+ONE: '';
+TWO: THREE: '';
+FOUR: '';
+'';
+SEVEN: '';
@@ -0,0 +1,6 @@
+"";
+ONE: "";
+TWO: THREE: "";
+FOUR: "";
+"";
+SEVEN: "";
@@ -5,4 +5,5 @@ var M;
     }
     M1.fn = fn;
 }(M || (M = {})), new class {
-}(), new Object();
+}(), new Object(), (x)=>''
+;
@@ -1,11 +1 @@
-var y;
-switch(y){
-    case 'a':
-        throw y;
-    default:
-        throw y;
-}
-for(;;)throw 0;
-for(;;)throw 0;
-for(var idx in {})throw idx;
-for(;;)throw null;
+throw void 0;
@@ -1,20 +1,3 @@
+var y;
 import * as swcHelpers from "@swc/helpers";
-switch(y){
-    case "a":
-        throw y;
-    default:
-        throw y;
-}
-for(;;)throw 0;
-for(;;)throw 0;
-for(var idx in {})throw idx;
-for(;;)throw null;
-var y, C = function() {
-    "use strict";
-    function C() {
-        throw swcHelpers.classCallCheck(this, C), this;
-    }
-    return C.prototype.biz = function() {
-        throw this.value;
-    }, C;
-}();
+throw y;
@@ -1 +1 @@
-isString1(0, ""), isString1(0, ""), isString2("");
+isString1(0, ""), isString2(""), isString1(0, ""), isString2("");
@@ -1 +1 @@
-isString1(0, ""), isString1(0, ""), isString2("");
+isString1(0, ""), isString2(""), isString1(0, ""), isString2("");
@@ -345,6 +345,16 @@ pub struct SwitchCase {
     pub cons: Vec<Stmt>,
 }
 
+impl Take for SwitchCase {
+    fn dummy() -> Self {
+        Self {
+            span: DUMMY_SP,
+            test: None,
+            cons: Vec::new(),
+        }
+    }
+}
+
 #[ast_node("CatchClause")]
 #[derive(Eq, Hash, EqIgnoreSpan)]
 #[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]

@@ -3,14 +3,11 @@ use std::mem::swap;
 use swc_common::{util::take::Take, EqIgnoreSpan, Spanned, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::ext::ExprRefExt;
-use swc_ecma_utils::{ident::IdentLike, ExprExt, ExprFactory, StmtLike};
+use swc_ecma_utils::{ident::IdentLike, ExprExt, ExprFactory, StmtExt, StmtLike};
 
 use super::Optimizer;
 use crate::{
-    compress::{
-        optimize::Ctx,
-        util::{always_terminates, negate_cost},
-    },
+    compress::{optimize::Ctx, util::negate_cost},
     mode::Mode,
     DISABLE_BUGGY_PASSES,
 };
@@ -701,7 +698,7 @@ where
                 cons,
                 alt: Some(..),
                 ..
-            })) => always_terminates(cons),
+            })) => cons.terminates(),
             _ => false,
         });
         if !need_work {
@@ -720,7 +717,7 @@ where
                         cons,
                         alt: Some(alt),
                         ..
-                    }) if always_terminates(&cons) => {
+                    }) if cons.terminates() => {
                         new_stmts.push(T::from_stmt(Stmt::If(IfStmt {
                             span,
                             test,

@@ -1,15 +1,10 @@
 use swc_common::{util::take::Take, Spanned, DUMMY_SP};
 use swc_ecma_ast::*;
-use swc_ecma_utils::{prepend, undefined, StmtLike};
+use swc_ecma_utils::{prepend, undefined, StmtExt, StmtLike};
 use swc_ecma_visit::{noop_visit_type, Visit, VisitWith};
 
 use super::Optimizer;
-use crate::{
-    compress::util::{always_terminates, is_pure_undefined},
-    debug::dump,
-    mode::Mode,
-    util::ExprOptExt,
-};
+use crate::{compress::util::is_pure_undefined, debug::dump, mode::Mode, util::ExprOptExt};
 
 /// Methods related to the option `if_return`. All methods are noop if
 /// `if_return` is false.
@@ -587,7 +582,7 @@ fn always_terminates_with_return_arg(s: &Stmt) -> bool {
 fn can_merge_as_if_return(s: &Stmt) -> bool {
     fn cost(s: &Stmt) -> Option<isize> {
         if let Stmt::Block(..) = s {
-            if !always_terminates(s) {
+            if !s.terminates() {
                 return None;
             }
         }

@@ -12,8 +12,8 @@ use swc_common::{
 };
 use swc_ecma_ast::*;
 use swc_ecma_utils::{
-    ident::IdentLike, prepend_stmts, undefined, ExprExt, ExprFactory, Id, IsEmpty, ModuleItemLike,
-    StmtLike, Type, Value,
+    extract_var_ids, ident::IdentLike, prepend_stmts, undefined, ExprExt, ExprFactory, Id, IsEmpty,
+    ModuleItemLike, StmtLike, Type, Value,
 };
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith, VisitWith};
 use tracing::{debug, span, Level};
@@ -133,8 +133,6 @@ struct Ctx {
     /// `true` while handling `expr` of `!expr`
     in_bang_arg: bool,
     in_var_decl_of_for_in_or_of_loop: bool,
-    /// `true` while handling inner statements of a labelled statement.
-    stmt_labelled: bool,
 
     dont_use_negated_iife: bool,
 
@@ -1551,7 +1549,6 @@ where
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
     fn visit_mut_block_stmt(&mut self, n: &mut BlockStmt) {
         let ctx = Ctx {
-            stmt_labelled: false,
             top_level: false,
             in_block: true,
             scope: n.span.ctxt,
@@ -1957,13 +1954,7 @@ where
 
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
     fn visit_mut_function(&mut self, n: &mut Function) {
-        {
-            let ctx = Ctx {
-                stmt_labelled: false,
-                ..self.ctx
-            };
-            n.decorators.visit_mut_with(&mut *self.with_ctx(ctx));
-        }
+        n.decorators.visit_mut_with(self);
 
         let is_standalone = n.span.has_mark(self.marks.standalone);
 
@@ -1978,7 +1969,6 @@ where
         {
             let ctx = Ctx {
                 skip_standalone: self.ctx.skip_standalone || is_standalone,
-                stmt_labelled: false,
                 in_fn_like: true,
                 scope: n.span.ctxt,
                 can_inline_arguments: true,
@@ -2044,13 +2034,9 @@ where
 
     #[cfg_attr(feature = "debug", tracing::instrument(skip_all))]
     fn visit_mut_labeled_stmt(&mut self, n: &mut LabeledStmt) {
-        let ctx = Ctx {
-            stmt_labelled: true,
-            ..self.ctx
-        };
         let old_label = self.label.take();
         self.label = Some(n.label.to_id());
-        n.visit_mut_children_with(&mut *self.with_ctx(ctx));
+        n.visit_mut_children_with(self);
 
         if self.label.is_none() {
             report_change!("Removing label `{}`", n.label);
@@ -2511,6 +2497,79 @@ where
         if cfg!(debug_assertions) {
             stmts.visit_with(&mut AssertValid);
         }
+
+        if self.options.dead_code {
+            // copy from [Remover]
+            // TODO: make it better
+            let orig_len = stmts.len();
+
+            let mut new_stmts = Vec::with_capacity(stmts.len());
+
+            let mut iter = stmts.take().into_iter();
+            while let Some(stmt) = iter.next() {
+                let stmt = match stmt {
+                    // Remove empty statements.
+                    Stmt::Empty(..) => continue,
+
+                    // Control flow
+                    Stmt::Throw(..)
+                    | Stmt::Return { .. }
+                    | Stmt::Continue { .. }
+                    | Stmt::Break { .. } => {
+                        // Hoist function and `var` declarations above return.
+                        let mut decls = vec![];
+                        let mut hoisted_fns = vec![];
+                        for t in iter {
+                            match t.try_into_stmt() {
+                                Ok(Stmt::Decl(Decl::Fn(f))) => {
+                                    hoisted_fns.push(Stmt::Decl(Decl::Fn(f)));
+                                }
+                                Ok(t) => {
+                                    let ids =
+                                        extract_var_ids(&t).into_iter().map(|i| VarDeclarator {
+                                            span: i.span,
+                                            name: i.into(),
+                                            init: None,
+                                            definite: false,
+                                        });
+                                    decls.extend(ids);
+                                }
+                                Err(item) => new_stmts.push(item),
+                            }
+                        }
+
+                        if !decls.is_empty() {
+                            new_stmts.push(Stmt::Decl(Decl::Var(VarDecl {
+                                span: DUMMY_SP,
+                                kind: VarDeclKind::Var,
+                                decls,
+                                declare: false,
+                            })));
+                        }
+
+                        new_stmts.push(stmt);
+                        new_stmts.extend(hoisted_fns);
+
+                        *stmts = new_stmts;
+                        if stmts.len() != orig_len {
+                            self.changed = true;
+
+                            if cfg!(feature = "debug") {
+                                debug!("Dropping statements after a control keyword");
+                            }
+                        }
+
+                        return;
+                    }
+
+                    _ => stmt,
+                };
+
+                new_stmts.push(stmt);
+            }
+
+            *stmts = new_stmts;
+        }
     }
 
     fn visit_mut_str(&mut self, s: &mut Str) {
@@ -2540,8 +2599,6 @@ where
     fn visit_mut_switch_stmt(&mut self, n: &mut SwitchStmt) {
         n.discriminant.visit_mut_with(self);
 
-        self.drop_unreachable_cases(n);
-
         n.cases.visit_mut_with(self);
     }