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oxc-project · Jan 1, 2025 · f8e94af · f8e94af
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commit f8e94af
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Showing 5 changed files with 46 additions and 24 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/crates/oxc_minifier/Cargo.toml b/crates/oxc_minifier/Cargo.toml
@@ -33,6 +33,7 @@ oxc_syntax = { workspace = true }
 oxc_traverse = { workspace = true }
 
 cow-utils = { workspace = true }
+rustc-hash = { workspace = true }
 
 [dev-dependencies]
 oxc_parser = { workspace = true }

diff --git a/crates/oxc_minifier/src/ast_passes/remove_unused_code.rs b/crates/oxc_minifier/src/ast_passes/remove_unused_code.rs
@@ -1,8 +1,7 @@
-use oxc_allocator::Vec;
 use oxc_ast::ast::*;
-use oxc_ecmascript::side_effects::MayHaveSideEffects;
-use oxc_span::SPAN;
+use oxc_syntax::symbol::SymbolId;
 use oxc_traverse::{traverse_mut_with_ctx, ReusableTraverseCtx, Traverse, TraverseCtx};
+use rustc_hash::FxHashSet;
 
 use crate::CompressorPass;
 
@@ -11,6 +10,8 @@ use crate::CompressorPass;
 /// <https://github.com/google/closure-compiler/blob/v20240609/src/com/google/javascript/jscomp/RemoveUnusedCode.java>
 pub struct RemoveUnusedCode {
     pub(crate) changed: bool,
+
+    symbol_ids_to_remove: FxHashSet<SymbolId>,
 }
 
 impl<'a> CompressorPass<'a> for RemoveUnusedCode {
@@ -20,11 +21,38 @@ impl<'a> CompressorPass<'a> for RemoveUnusedCode {
     }
 }
 
-impl<'a> Traverse<'a> for RemoveUnusedCode {}
+impl<'a> Traverse<'a> for RemoveUnusedCode {
+    fn enter_program(&mut self, _node: &mut Program<'a>, ctx: &mut TraverseCtx<'a>) {
+        let symbols = ctx.symbols();
+        for symbol_id in symbols.symbol_ids() {
+            if symbols.get_resolved_references(symbol_id).count() == 0 {
+                self.symbol_ids_to_remove.insert(symbol_id);
+            }
+        }
+    }
+
+    fn exit_statement(&mut self, stmt: &mut Statement<'a>, ctx: &mut TraverseCtx<'a>) {
+        if let Statement::VariableDeclaration(decl) = stmt {
+            decl.declarations.retain(|d| {
+                if let BindingPatternKind::BindingIdentifier(ident) = &d.id.kind {
+                    if d.init.is_none() {
+                        if self.symbol_ids_to_remove.contains(&ident.symbol_id()) {
+                            return false;
+                        }
+                    }
+                }
+                true
+            });
+            if decl.declarations.is_empty() {
+                *stmt = ctx.ast.statement_empty(decl.span);
+            }
+        }
+    }
+}
 
 impl<'a> RemoveUnusedCode {
     pub fn new() -> Self {
-        Self { changed: false }
+        Self { changed: false, symbol_ids_to_remove: FxHashSet::default() }
     }
 }
 

diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
@@ -21,7 +21,7 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 3.20 MB    | 1.01 MB    | 1.01 MB    | 332.14 kB  | 331.56 kB  | echarts.js
 
-6.69 MB    | 2.32 MB    | 2.31 MB    | 493.00 kB  | 488.28 kB  | antd.js   
+6.69 MB    | 2.32 MB    | 2.31 MB    | 493.01 kB  | 488.28 kB  | antd.js   
 
 10.95 MB   | 3.51 MB    | 3.49 MB    | 910.09 kB  | 915.50 kB  | typescript.js
 
diff --git a/tasks/minsize/src/lib.rs b/tasks/minsize/src/lib.rs
@@ -10,7 +10,7 @@ use flate2::{write::GzEncoder, Compression};
 use humansize::{format_size, DECIMAL};
 use oxc_allocator::Allocator;
 use oxc_codegen::{CodeGenerator, CodegenOptions};
-use oxc_minifier::{CompressOptions, MangleOptions, Minifier, MinifierOptions};
+use oxc_minifier::{Minifier, MinifierOptions};
 use oxc_parser::Parser;
 use oxc_semantic::SemanticBuilder;
 use oxc_span::SourceType;
@@ -126,17 +126,13 @@ pub fn run() -> Result<(), io::Error> {
 
 fn minify_twice(file: &TestFile) -> String {
     let source_type = SourceType::from_path(&file.file_name).unwrap();
-    let options = MinifierOptions {
-        mangle: Some(MangleOptions::default()),
-        compress: CompressOptions::default(),
-    };
-    let source_text1 = minify(&file.source_text, source_type, options);
-    let source_text2 = minify(&source_text1, source_type, options);
-    assert_eq_minified_code(&source_text1, &source_text2, &file.file_name);
-    source_text2
+    let code1 = minify(&file.source_text, source_type);
+    let code2 = minify(&code1, source_type);
+    assert_eq_minified_code(&code1, &code2, &file.file_name);
+    code2
 }
 
-fn minify(source_text: &str, source_type: SourceType, options: MinifierOptions) -> String {
+fn minify(source_text: &str, source_type: SourceType) -> String {
     let allocator = Allocator::default();
     let ret = Parser::new(&allocator, source_text, source_type).parse();
     let mut program = ret.program;
@@ -147,7 +143,7 @@ fn minify(source_text: &str, source_type: SourceType, options: MinifierOptions)
         ReplaceGlobalDefinesConfig::new(&[("process.env.NODE_ENV", "'development'")]).unwrap(),
     )
     .build(symbols, scopes, &mut program);
-    let ret = Minifier::new(options).build(&allocator, &mut program);
+    let ret = Minifier::new(MinifierOptions::default()).build(&allocator, &mut program);
     CodeGenerator::new()
         .with_options(CodegenOptions { minify: true, ..CodegenOptions::default() })
         .with_mangler(ret.mangler)
@@ -164,13 +160,9 @@ fn gzip_size(s: &str) -> usize {
 
 fn assert_eq_minified_code(s1: &str, s2: &str, filename: &str) {
     if s1 != s2 {
-        let normalized_left = normalize_minified_code(s1);
-        let normalized_right = normalize_minified_code(s2);
-        similar_asserts::assert_eq!(
-            normalized_left,
-            normalized_right,
-            "Minification failed for {filename}"
-        );
+        let left = normalize_minified_code(s1);
+        let right = normalize_minified_code(s2);
+        similar_asserts::assert_eq!(left, right, "Minification failed for {filename}");
     }
 }