From 47276679f584d79b3d82243e44dd9cdb81878c6f Mon Sep 17 00:00:00 2001
From: Boshen <1430279+Boshen@users.noreply.github.com>
Date: Tue, 24 Dec 2024 14:25:01 +0000
Subject: [PATCH] feat(codegen): minify arrow expr `(x) => y` -> `x => y`
 (#8078)

---
 crates/oxc_codegen/src/gen.rs                | 19 ++++++++++++++++---
 crates/oxc_codegen/tests/integration/unit.rs | 16 ++++++++--------
 tasks/minsize/minsize.snap                   |  6 +++---
 3 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/crates/oxc_codegen/src/gen.rs b/crates/oxc_codegen/src/gen.rs
index 5b20c8f385474..549624b3f1d98 100644
--- a/crates/oxc_codegen/src/gen.rs
+++ b/crates/oxc_codegen/src/gen.rs
@@ -1791,9 +1791,22 @@ impl GenExpr for ArrowFunctionExpression<'_> {
                 type_parameters.print(p, ctx);
             }
             p.add_source_mapping(self.span);
-            p.print_ascii_byte(b'(');
-            self.params.print(p, ctx);
-            p.print_ascii_byte(b')');
+            let remove_params_wrap = p.options.minify
+                && self.params.items.len() == 1
+                && self.params.rest.is_none()
+                && self.type_parameters.is_none()
+                && self.return_type.is_none()
+                && {
+                    let param = &self.params.items[0];
+                    param.decorators.is_empty()
+                        && !param.has_modifier()
+                        && param.pattern.kind.is_binding_identifier()
+                        && param.pattern.type_annotation.is_none()
+                        && !param.pattern.optional
+                };
+            p.wrap(!remove_params_wrap, |p| {
+                self.params.print(p, ctx);
+            });
             if let Some(return_type) = &self.return_type {
                 p.print_str(":");
                 p.print_soft_space();
diff --git a/crates/oxc_codegen/tests/integration/unit.rs b/crates/oxc_codegen/tests/integration/unit.rs
index fa0434aed7fdc..1a8525f828e94 100644
--- a/crates/oxc_codegen/tests/integration/unit.rs
+++ b/crates/oxc_codegen/tests/integration/unit.rs
@@ -189,14 +189,14 @@ fn r#yield() {
 
 #[test]
 fn arrow() {
-    test_minify("x => a, b", "(x)=>a,b;");
-    test_minify("x => (a, b)", "(x)=>(a,b);");
-    test_minify("x => (a => b)", "(x)=>(a)=>b;");
-    test_minify("x => y => a, b", "(x)=>(y)=>a,b;");
-    test_minify("x => y => (a = b)", "(x)=>(y)=>a=b;");
-    test_minify("x => y => z => a = b, c", "(x)=>(y)=>(z)=>a=b,c;");
-    test_minify("x => y => z => a = (b, c)", "(x)=>(y)=>(z)=>a=(b,c);");
-    test_minify("x => ({} + 0)", "(x)=>({})+0;");
+    test_minify("x => a, b", "x=>a,b;");
+    test_minify("x => (a, b)", "x=>(a,b);");
+    test_minify("x => (a => b)", "x=>a=>b;");
+    test_minify("x => y => a, b", "x=>y=>a,b;");
+    test_minify("x => y => (a = b)", "x=>y=>a=b;");
+    test_minify("x => y => z => a = b, c", "x=>y=>z=>a=b,c;");
+    test_minify("x => y => z => a = (b, c)", "x=>y=>z=>a=(b,c);");
+    test_minify("x => ({} + 0)", "x=>({})+0;");
 }
 
 #[test]
diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
index d5f589c8b3033..76c69877c44b5 100644
--- a/tasks/minsize/minsize.snap
+++ b/tasks/minsize/minsize.snap
@@ -11,13 +11,13 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 544.10 kB  | 73.32 kB   | 72.48 kB   | 26.13 kB   | 26.20 kB   | lodash.js 
 
-555.77 kB  | 276.06 kB  | 270.13 kB  | 91.14 kB   | 90.80 kB   | d3.js     
+555.77 kB  | 276.01 kB  | 270.13 kB  | 91.13 kB   | 90.80 kB   | d3.js     
 
-1.01 MB    | 466.82 kB  | 458.89 kB  | 126.74 kB  | 126.71 kB  | bundle.min.js
+1.01 MB    | 466.62 kB  | 458.89 kB  | 126.69 kB  | 126.71 kB  | bundle.min.js
 
 1.25 MB    | 661.47 kB  | 646.76 kB  | 163.94 kB  | 163.73 kB  | three.js  
 
-2.14 MB    | 740.44 kB  | 724.14 kB  | 181.35 kB  | 181.07 kB  | victory.js
+2.14 MB    | 740.43 kB  | 724.14 kB  | 181.34 kB  | 181.07 kB  | victory.js
 
 3.20 MB    | 1.02 MB    | 1.01 MB    | 332.00 kB  | 331.56 kB  | echarts.js