From cdc39ff7e5f8f2dda6a2f745a38ffb8751888fa9 Mon Sep 17 00:00:00 2001
From: Boshen <boshenc@gmail.com>
Date: Fri, 10 Jan 2025 18:16:55 +0800
Subject: [PATCH] feat(minifier): fold `ambiguous if else`

---
 .../oxc_minifier/src/ast_passes/normalize.rs  | 25 +++++++++++++++++--
 crates/oxc_minifier/tests/ast_passes/mod.rs   | 19 ++++++++++++++
 tasks/minsize/src/lib.rs                      |  1 +
 3 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/crates/oxc_minifier/src/ast_passes/normalize.rs b/crates/oxc_minifier/src/ast_passes/normalize.rs
index c99232e9911b0..c7b613838dc1b 100644
--- a/crates/oxc_minifier/src/ast_passes/normalize.rs
+++ b/crates/oxc_minifier/src/ast_passes/normalize.rs
@@ -1,4 +1,5 @@
 use oxc_ast::ast::*;
+use oxc_span::GetSpan;
 use oxc_syntax::scope::ScopeFlags;
 use oxc_traverse::{traverse_mut_with_ctx, ReusableTraverseCtx, Traverse, TraverseCtx};
 
@@ -23,8 +24,12 @@ impl<'a> CompressorPass<'a> for Normalize {
 
 impl<'a> Traverse<'a> for Normalize {
     fn exit_statement(&mut self, stmt: &mut Statement<'a>, ctx: &mut TraverseCtx<'a>) {
-        if matches!(stmt, Statement::WhileStatement(_)) {
-            Self::convert_while_to_for(stmt, ctx);
+        match stmt {
+            Statement::WhileStatement(_) => {
+                Self::convert_while_to_for(stmt, ctx);
+            }
+            Statement::IfStatement(s) => Self::wrap_to_avoid_ambiguous_else(s, ctx),
+            _ => {}
         }
     }
 
@@ -68,6 +73,22 @@ impl<'a> Normalize {
                 ctx.ast.expression_numeric_literal(ident.span, value, None, NumberBase::Decimal);
         }
     }
+
+    // Wrap to avoid ambiguous else.
+    // `if (foo) if (bar) baz else quaz` ->  `if (foo) { if (bar) baz else quaz }`
+    fn wrap_to_avoid_ambiguous_else(if_stmt: &mut IfStatement<'a>, ctx: &mut TraverseCtx<'a>) {
+        if let Statement::IfStatement(if2) = &mut if_stmt.consequent {
+            if if2.alternate.is_some() {
+                let scope_id = ctx.create_child_scope_of_current(ScopeFlags::empty());
+                if_stmt.consequent =
+                    Statement::BlockStatement(ctx.ast.alloc_block_statement_with_scope_id(
+                        if_stmt.consequent.span(),
+                        ctx.ast.vec1(ctx.ast.move_statement(&mut if_stmt.consequent)),
+                        scope_id,
+                    ));
+            }
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/oxc_minifier/tests/ast_passes/mod.rs b/crates/oxc_minifier/tests/ast_passes/mod.rs
index ca5a0258a26f2..c58a2ecfc4f9c 100644
--- a/crates/oxc_minifier/tests/ast_passes/mod.rs
+++ b/crates/oxc_minifier/tests/ast_passes/mod.rs
@@ -13,6 +13,25 @@ fn test_same(source_text: &str) {
 
 // Oxc Integration Tests
 
+#[test]
+fn integration() {
+    test(
+        "function writeInteger(int) {
+          if (int >= 0)
+            if (int <= 0xffffffff)
+              return this.u32(int);
+            else if (int > -0x80000000)
+              return this.n32(int);
+        }",
+        "function writeInteger(int) {
+          if (int >= 0) {
+            if (int <= 4294967295) return this.u32(int);
+            if (int > -2147483648) return this.n32(int);
+          }
+        }",
+    );
+}
+
 #[test] // https://github.com/oxc-project/oxc/issues/4341
 fn tagged_template() {
     test_same("(1, o.f)()");
diff --git a/tasks/minsize/src/lib.rs b/tasks/minsize/src/lib.rs
index 516e503c813fc..2a354e7e457e6 100644
--- a/tasks/minsize/src/lib.rs
+++ b/tasks/minsize/src/lib.rs
@@ -98,6 +98,7 @@ pub fn run() -> Result<(), io::Error> {
     let save_path = Path::new("./target/minifier").join(marker);
 
     for file in files.files() {
+        println!("{}", &file.file_name);
         let minified = minify_twice(file);
 
         fs::create_dir_all(&save_path).unwrap();