feat(es/minifier): Add pristine_globals (#4480)

crates/swc_ecma_minifier/src/compress/pure/misc.rs

@@ -806,7 +806,7 @@ impl Pure<'_> {
             _ => {}
         }
 
-        if self.options.side_effects {
+        if self.options.side_effects && self.options.pristine_globals {
             if let Expr::New(NewExpr { callee, args, .. }) = e {
                 if let Expr::Ident(i) = &**callee {
                     match &*i.sym {
@@ -830,6 +830,7 @@ impl Pure<'_> {
         }
 
         // Remove pure member expressions.
+        if self.options.pristine_globals {
             if let Expr::Member(MemberExpr { obj, prop, .. }) = e {
                 if let Expr::Ident(obj) = &**obj {
                     if obj.span.ctxt.outer() == self.marks.unresolved_mark {
@@ -843,6 +844,7 @@ impl Pure<'_> {
             }
         }
     }
+}
 
 #[derive(Debug, Default, Clone, Copy)]
 pub(super) struct DropOpts {

crates/swc_ecma_minifier/src/option/mod.rs

@@ -311,6 +311,12 @@ pub struct CompressOptions {
 
     #[serde(default = "true_by_default")]
     pub const_to_let: bool,
+
+    /// If you modified globals, set this to false.
+    ///
+    /// Defaults to true.
+    #[serde(default = "true_by_default")]
+    pub pristine_globals: bool,
 }
 
 impl CompressOptions {

crates/swc_ecma_minifier/src/option/terser.rs

@@ -242,6 +242,9 @@ pub struct TerserCompressorOptions {
 
     #[serde(default)]
     pub const_to_let: Option<bool>,
+
+    #[serde(default)]
+    pub pristine_globals: Option<bool>,
 }
 
 impl Default for TerserCompressorOptions {
@@ -388,6 +391,7 @@ impl TerserCompressorOptions {
             unsafe_undefined: self.unsafe_undefined,
             unused: self.unused.unwrap_or(self.defaults),
             const_to_let: self.const_to_let.unwrap_or(self.defaults),
+            pristine_globals: self.pristine_globals.unwrap_or(self.defaults),
         }
     }
 }

crates/swc_ecma_minifier/tests/compress.rs

@@ -126,6 +126,7 @@ fn parse_compressor_config(cm: Lrc<SourceMap>, s: &str) -> (bool, CompressOption
 
     c.defaults = opts.defaults;
     c.const_to_let = Some(false);
+    c.pristine_globals = Some(true);
     c.passes = opts.passes;
 
     (c.module, c.into_config(cm))