fix(es/minifier): Preserve this in more cases

crates/swc_ecma_ast/Cargo.toml

@@ -33,7 +33,7 @@ rkyv-bytecheck-impl = [
 arbitrary  = { version = "1", optional = true, features = ["derive"] }
 bitflags   = "1"
 bytecheck  = { version = "0.6.9", optional = true }
-is-macro   = "0.2.0"
+is-macro   = "0.2.1"
 num-bigint = { version = "0.4", features = ["serde"] }
 rkyv       = { package = "rkyv", version = "=0.7.37", optional = true }
 # This is to avoid cargo version selection conflict between rkyv=0.7.37 and other versions, as it is strictly pinned

crates/swc_ecma_ast/src/expr.rs

@@ -8,7 +8,7 @@ use serde::{
     Deserialize, Deserializer, Serialize,
 };
 use string_enum::StringEnum;
-use swc_atoms::Atom;
+use swc_atoms::{js_word, Atom};
 use swc_common::{ast_node, util::take::Take, BytePos, EqIgnoreSpan, Span, Spanned, DUMMY_SP};
 
 use crate::{
@@ -215,6 +215,17 @@ impl Expr {
             }))
         }
     }
+
+    /// Returns true for `eval` and member expressions.
+    pub fn directness_maters(&self) -> bool {
+        matches!(
+            self,
+            Expr::Ident(Ident {
+                sym: js_word!("eval"),
+                ..
+            }) | Expr::Member(..)
+        )
+    }
 }
 
 // Implement Clone without inline to avoid multiple copies of the

crates/swc_ecma_minifier/tests/fixture/issues/6175/1/input.js

@@ -0,0 +1,11 @@
+let o = {
+    f() {
+        assert.ok(this !== o);
+    }
+};
+(1, o.f)``;
+(true ? o.f : false)``;
+(true && o.f)``;
+
+let a;
+(a = o.f)``;

crates/swc_ecma_minifier/tests/fixture/issues/6175/1/output.js

@@ -0,0 +1,6 @@
+let o = {
+    f () {
+        assert.ok(this !== o);
+    }
+};
+(0, o.f)``, (0, o.f)``, (0, o.f)``;

crates/swc_ecma_transforms_optimization/src/simplify/expr/mod.rs

@@ -483,7 +483,7 @@ impl SimplifyExpr {
                             self.changed = true;
 
                             // 0 && $right
-                            *expr = *(left.take());
+                            *expr = *left.take();
                             return;
                         }
                     } else if val {
@@ -500,7 +500,14 @@ impl SimplifyExpr {
                     if !left.may_have_side_effects(&self.expr_ctx) {
                         self.changed = true;
 
-                        *expr = *node.take();
+                        if node.directness_maters() {
+                            *expr = Expr::Seq(SeqExpr {
+                                span: node.span(),
+                                exprs: vec![0.into(), node.take()],
+                            });
+                        } else {
+                            *expr = *node.take();
+                        }
                     } else {
                         self.changed = true;
 
@@ -1330,7 +1337,14 @@ impl VisitMut for SimplifyExpr {
 
                     let expr_value = if val { cons } else { alt };
                     *expr = if p.is_pure() {
-                        *(expr_value.take())
+                        if expr_value.directness_maters() {
+                            Expr::Seq(SeqExpr {
+                                span: *span,
+                                exprs: vec![0.into(), expr_value.take()],
+                            })
+                        } else {
+                            *expr_value.take()
+                        }
                     } else {
                         Expr::Seq(SeqExpr {
                             span: *span,