minifier: re-sugar lowered optional chains, shortest numbers, and small peepholes

src/ast/symbol.rs

@@ -122,6 +122,12 @@ bitflags::bitflags! {
         /// `arguments` object can). Set on the root of the symbol's link
         /// chain. Read by HMR live bindings and the printer's same-target fold.
         const HAS_BEEN_ASSIGNED_TO = 1 << 5;
+
+        /// Another symbol's `link` points at this one (a hoisted `var`
+        /// redeclaration, a catch binding, a replaced declaration), so uses
+        /// recorded on that symbol are uses of this one too and
+        /// `use_count_estimate` alone undercounts them.
+        const IS_LINK_TARGET = 1 << 6;
     }
 }
 
@@ -147,6 +153,7 @@ symbol_flag_accessors! {
     must_not_be_renamed, set_must_not_be_renamed => MUST_NOT_BE_RENAMED;
     remove_overwritten_function_declaration, set_remove_overwritten_function_declaration => REMOVE_OVERWRITTEN_FUNCTION_DECLARATION;
     has_been_assigned_to, set_has_been_assigned_to => HAS_BEEN_ASSIGNED_TO;
+    is_link_target, set_is_link_target => IS_LINK_TARGET;
 }
 
 const _: () = assert!(core::mem::size_of::<Option<bun_alloc::AstBox<G::NamespaceAlias>>>() == 8);

src/bun_core/fmt.rs

@@ -3252,25 +3252,6 @@ pub fn itoa<T: ::itoa::Integer>(buf: &mut ItoaBuf, n: T) -> &[u8] {
     buf.format(n).as_bytes()
 }
 
-/// If `val` is exactly `10^e` for `e` in `4..=9`, return `Some(e)`; else `None`.
-///
-/// Used by `js_printer`'s non-negative-integer fast path to emit the
-/// minified-JS forms `1e4`..`1e9` (which are shorter than the full digit
-/// expansion). `e ≤ 3` is not shorter; `e ≥ 10` exceeds `u32::MAX` and is
-/// handled by the printer's f64 path.
-#[inline]
-pub const fn pow10_exp_1e4_to_1e9(val: u64) -> Option<u8> {
-    match val {
-        10_000 => Some(4),
-        100_000 => Some(5),
-        1_000_000 => Some(6),
-        10_000_000 => Some(7),
-        100_000_000 => Some(8),
-        1_000_000_000 => Some(9),
-        _ => None,
-    }
-}
-
 /// Format `value`
 /// into `buf` as base-10 ASCII and return the number of bytes written.
 /// Panics if `buf` is too small — callers size the buffer by the type's max

src/js_parser/lower/lower_esm_exports_hmr.rs

@@ -468,6 +468,7 @@ impl<'a> ConvertESMExportsForHmr<'a> {
                     let symbol = &mut p.symbols[namespace_ref.inner_index() as usize];
                     symbol.use_count_estimate = 0;
                     symbol.link.set(stmt.namespace_ref);
+                    p.symbols[stmt.namespace_ref.inner_index() as usize].set_is_link_target(true);
                     // Note: the concrete `P` always carries `symbol_uses`;
                     // once a `ParserLike` trait is introduced for
                     // AstBuilder, that variant should override this to a no-op.

src/js_parser/p.rs

@@ -508,6 +508,8 @@ pub struct P<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> {
     pub(crate) stmt_expr_value: js_ast::ExprData,
     pub(crate) call_target: js_ast::ExprData,
     pub(crate) delete_target: js_ast::ExprData,
+    /// The tag of the template literal being visited, like `call_target`.
+    pub(crate) template_tag: js_ast::ExprData,
     pub(crate) loop_body: js_ast::StmtData,
     pub(crate) module_scope: js_ast::StoreRef<js_ast::Scope>,
     pub(crate) module_scope_directive_loc: bun_ast::Loc,
@@ -599,6 +601,14 @@ pub struct P<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> {
     pub(crate) temp_refs_to_declare: List<'a, TempRef>,
     pub(crate) temp_ref_count: i32,
 
+    /// Rewrites that wait for the enclosing function body's use counts to be
+    /// final. Entries past the depth's saved length belong to the body being
+    /// visited; see `apply_fn_body_mangle_candidates`.
+    pub(crate) mangle_candidates: Vec<crate::visit::mangle::MangleCandidate>,
+    /// How many function bodies are being visited. Candidates are only
+    /// recorded inside one, since the module scope is visited part by part.
+    pub(crate) fn_body_depth: u32,
+
     // When bundling, hoisted top-level local variables declared with "var" in
     // nested scopes are moved up to be declared in the top-level scope instead.
     // The old "var" statements are turned into regular assignments instead. This
@@ -3397,6 +3407,7 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                             {
                                 // Silently merge this symbol into the existing symbol
                                 self.symbols[symbol_idx].link.set(member_in_scope.ref_);
+                                self.symbols[existing_idx].set_is_link_target(true);
                                 // `StringHashMap` get_or_put already stores the key on insert and
                                 // cannot hand out `&mut K` (see StringHashMapGetOrPut docs), so
                                 // no key write is needed here.
@@ -3457,6 +3468,7 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                             // If this is a catch identifier, silently merge the existing symbol
                             // into this symbol but continue hoisting past this catch scope
                             self.symbols[existing_idx].link.set(value.ref_);
+                            self.symbols[symbol_idx].set_is_link_target(true);
                             *_scope
                                 .get_or_put_member_with_hash(name, hash.unwrap())
                                 .value_ptr = value;
@@ -4894,6 +4906,7 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
                 }
                 MR::ReplaceWithNew => {
                     self.symbols[symbol_idx].link.set(ref_);
+                    self.symbols[ref_.inner_index() as usize].set_is_link_target(true);
 
                     // If these are both functions, remove the overwritten declaration
                     if kind.is_function() && self.symbols[symbol_idx].kind.is_function() {
@@ -9170,6 +9183,7 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
             allow_in: true,
 
             call_target: null_expr_data(),
+            template_tag: null_expr_data(),
             delete_target: null_expr_data(),
             stmt_expr_value: null_expr_data(),
             loop_body: null_stmt_data(),
@@ -9283,6 +9297,8 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
             has_non_local_export_declare_inside_namespace: false,
             await_target: None,
             temp_refs_to_declare: BumpVec::new_in(arena),
+            mangle_candidates: Vec::new(),
+            fn_body_depth: 0,
             temp_ref_count: 0,
             relocated_top_level_vars: BumpVec::new_in(arena),
             after_arrow_body_loc: bun_ast::Loc::EMPTY,