fix(minifier): disallow merging assignments to let declarations when TDZ error would be introduced

crates/oxc_minifier/src/peephole/minimize_statements.rs

@@ -520,7 +520,10 @@ impl<'a> PeepholeOptimizations {
                 break;
             };
             if kind.name == id.name {
-                if decl.init.is_none() {
+                if decl.init.is_none()
+                    && (decl.kind == VariableDeclarationKind::Var
+                        || assign_expr.right.is_literal_value(true, ctx))
+                {
                     // "var a; a = b();" => "var a = b();"
                     decl.init = Some(assign_expr.right.take_in(ctx.ast));
                     return true;
@@ -530,6 +533,8 @@ impl<'a> PeepholeOptimizations {
                 //   This is not possible as we need to consider cases when `c()` accesses `a`
                 // - "var a = 1; a = b();" => "var a = b();"
                 //   This is not possible as we need to consider cases when `b()` accesses `a`
+                // - "let a; a = foo(a);" => "let a = foo(a);"
+                //   This is not possible as TDZ error would be introduced
                 break;
             }
             // should not move assignment above variables with initializer to keep the execution order

crates/oxc_minifier/tests/peephole/merge_assignments_to_declarations.rs

@@ -35,6 +35,9 @@ fn merge_assignments_to_declarations_let() {
     test_same("let a, b; a = c()"); // `c()` may access `b`, `let a = c(), b` will cause TDZ error
     test("let a, b; a = c(); b = d()", "let a, b; a = c(), b = d()"); // same as above
     test("let a, b; a = b", "let a, b; a = void 0"); // `let a = b, b` will cause TDZ error
+    test_same("let a; a = foo(a)"); // `let a = foo(a)` will cause TDZ error
+    test_same("let a; a = (() => a)()"); // `let a = (() => a)()` will cause TDZ error
+    test("let a; a = () => a", "let a = () => a");
 }
 
 #[test]

tasks/track_memory_allocations/allocs_minifier.snap

@@ -2,7 +2,7 @@ File                       | File size      || Sys allocs     | Sys reallocs   |
 -------------------------------------------------------------------------------------------------------------------------------------------
 RadixUIAdoptionSection.jsx | 2.52 kB        ||             75 |              4 ||             20 |              6 | 688 B         
 
-pdf.mjs                    | 567.30 kB      ||          19577 |           2898 ||          47403 |           7782 | 1.624 MB      
+pdf.mjs                    | 567.30 kB      ||          19577 |           2900 ||          47405 |           7784 | 1.625 MB      
 
 antd.js                    | 6.69 MB        ||          99854 |          13518 ||         331725 |          70117 | 17.407 MB