feat(minifier): minimize foo ? foo : bar and foo ? bar : foo (#8229)

Cargo.toml

@@ -98,7 +98,6 @@ oxc_semantic = { version = "0.44.0", path = "crates/oxc_semantic" }
 oxc_span = { version = "0.44.0", path = "crates/oxc_span" }
 oxc_syntax = { version = "0.44.0", path = "crates/oxc_syntax" }
 oxc_transform_napi = { version = "0.44.0", path = "napi/transform" }
-oxc_parser_napi = { version = "0.44.0", path = "napi/parser" }
 oxc_transformer = { version = "0.44.0", path = "crates/oxc_transformer" }
 oxc_traverse = { version = "0.44.0", path = "crates/oxc_traverse" }
 

crates/oxc_minifier/src/ast_passes/peephole_substitute_alternate_syntax.rs

@@ -97,6 +97,7 @@ impl<'a> Traverse<'a> for PeepholeSubstituteAlternateSyntax {
             Expression::NewExpression(e) => Self::try_fold_new_expression(e, ctx),
             Expression::TemplateLiteral(t) => Self::try_fold_template_literal(t, ctx),
             Expression::BinaryExpression(e) => Self::try_compress_typeof_undefined(e, ctx),
+            Expression::ConditionalExpression(e) => Self::try_compress_conditional(e, ctx),
             Expression::CallExpression(e) => {
                 Self::try_fold_literal_constructor_call_expression(e, ctx)
                     .or_else(|| Self::try_fold_simple_function_call(e, ctx))
@@ -265,6 +266,37 @@ impl<'a, 'b> PeepholeSubstituteAlternateSyntax {
         Some(ctx.ast.expression_binary(expr.span, left, new_comp_op, right))
     }
 
+    fn try_compress_conditional(
+        expr: &mut ConditionalExpression<'a>,
+        ctx: Ctx<'a, 'b>,
+    ) -> Option<Expression<'a>> {
+        if let Expression::Identifier(ident_test) = &expr.test {
+            // `foo ? foo : bar` -> `foo || bar`
+            if let Expression::Identifier(ident_consequent) = &expr.consequent {
+                if ident_test.name == ident_consequent.name {
+                    return Some(ctx.ast.expression_logical(
+                        expr.span,
+                        ctx.ast.move_expression(&mut expr.test),
+                        LogicalOperator::Or,
+                        ctx.ast.move_expression(&mut expr.alternate),
+                    ));
+                }
+            }
+            // `foo ? bar : foo` -> `foo && bar`
+            if let Expression::Identifier(ident_alternate) = &expr.alternate {
+                if ident_test.name == ident_alternate.name {
+                    return Some(ctx.ast.expression_logical(
+                        expr.span,
+                        ctx.ast.move_expression(&mut expr.test),
+                        LogicalOperator::And,
+                        ctx.ast.move_expression(&mut expr.consequent),
+                    ));
+                }
+            }
+        }
+        None
+    }
+
     /// Compress `foo === null || foo === undefined` into `foo == null`.
     ///
     /// `foo === null || foo === undefined` => `foo == null`
@@ -1179,4 +1211,12 @@ mod test {
         test("typeof foo !== `number`", "typeof foo != 'number'");
         test("`number` !== typeof foo", "typeof foo != 'number'");
     }
+
+    #[test]
+    fn compress_conditional() {
+        test("foo ? foo : bar", "foo || bar");
+        test("foo ? bar : foo", "foo && bar");
+        test_same("x.y ? x.y : bar");
+        test_same("x.y ? bar : x.y");
+    }
 }

tasks/minsize/minsize.snap

@@ -7,13 +7,13 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 287.63 kB  | 90.16 kB   | 90.07 kB   | 32.08 kB   | 31.95 kB   | jquery.js 
 
-342.15 kB  | 118.23 kB  | 118.14 kB  | 44.53 kB   | 44.37 kB   | vue.js    
+342.15 kB  | 118.23 kB  | 118.14 kB  | 44.52 kB   | 44.37 kB   | vue.js    
 
 544.10 kB  | 71.81 kB   | 72.48 kB   | 26.19 kB   | 26.20 kB   | lodash.js 
 
 555.77 kB  | 273.19 kB  | 270.13 kB  | 90.99 kB   | 90.80 kB   | d3.js     
 
-1.01 MB    | 460.32 kB  | 458.89 kB  | 126.85 kB  | 126.71 kB  | bundle.min.js
+1.01 MB    | 460.32 kB  | 458.89 kB  | 126.84 kB  | 126.71 kB  | bundle.min.js
 
 1.25 MB    | 652.73 kB  | 646.76 kB  | 163.55 kB  | 163.73 kB  | three.js  
 
@@ -23,5 +23,5 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 6.69 MB    | 2.32 MB    | 2.31 MB    | 492.81 kB  | 488.28 kB  | antd.js   
 
-10.95 MB   | 3.50 MB    | 3.49 MB    | 909.54 kB  | 915.50 kB  | typescript.js
+10.95 MB   | 3.50 MB    | 3.49 MB    | 909.52 kB  | 915.50 kB  | typescript.js