fix(es/minifier): Don't inline functions if keep_fnames is enabled (#…

…8093)

**Related issue:**

 - vercel/next.js#56550

crates/swc_ecma_minifier/src/compress/mod.rs

@@ -28,7 +28,7 @@ use crate::{
     compress::hoist_decls::decl_hoister,
     debug::{dump, AssertValid},
     mode::Mode,
-    option::CompressOptions,
+    option::{CompressOptions, MangleOptions},
     program_data::{analyze, ProgramData},
     util::{now, unit::CompileUnit},
 };
@@ -41,6 +41,7 @@ mod util;
 pub(crate) fn compressor<'a, M>(
     marks: Marks,
     options: &'a CompressOptions,
+    mangle_options: Option<&'a MangleOptions>,
     mode: &'a M,
 ) -> impl 'a + VisitMut
 where
@@ -49,6 +50,7 @@ where
     let compressor = Compressor {
         marks,
         options,
+        mangle_options,
         changed: false,
         pass: 1,
         dump_for_infinite_loop: Default::default(),
@@ -70,6 +72,7 @@ where
 struct Compressor<'a> {
     marks: Marks,
     options: &'a CompressOptions,
+    mangle_options: Option<&'a MangleOptions>,
     changed: bool,
     pass: usize,
 
@@ -269,6 +272,7 @@ impl Compressor<'_> {
             let mut visitor = optimizer(
                 self.marks,
                 self.options,
+                self.mangle_options,
                 &mut data,
                 self.mode,
                 !self.dump_for_infinite_loop.is_empty(),

crates/swc_ecma_minifier/src/compress/optimize/inline.rs

@@ -203,6 +203,14 @@ impl Optimizer<'_> {
                                 )
                             }
 
+                            if u.declared_as_fn_decl || u.declared_as_fn_expr {
+                                if self.options.keep_fnames
+                                    || self.mangle_options.map_or(false, |v| v.keep_fn_names)
+                                {
+                                    should_inline = false
+                                }
+                            }
+
                             should_inline
                         } else {
                             false
@@ -411,6 +419,14 @@ impl Optimizer<'_> {
                             if init_usage.reassigned || !init_usage.declared {
                                 return;
                             }
+
+                            if init_usage.declared_as_fn_decl || init_usage.declared_as_fn_expr {
+                                if self.options.keep_fnames
+                                    || self.mangle_options.map_or(false, |v| v.keep_fn_names)
+                                {
+                                    return;
+                                }
+                            }
                         }
                     }
 

crates/swc_ecma_minifier/src/compress/optimize/mod.rs

@@ -30,7 +30,7 @@ use crate::{
     debug::AssertValid,
     maybe_par,
     mode::Mode,
-    option::CompressOptions,
+    option::{CompressOptions, MangleOptions},
     program_data::ProgramData,
     util::{
         contains_eval, contains_leaping_continue_with_label, make_number, ExprOptExt, ModuleItemExt,
@@ -59,6 +59,7 @@ mod util;
 pub(super) fn optimizer<'a>(
     marks: Marks,
     options: &'a CompressOptions,
+    mangle_options: Option<&'a MangleOptions>,
     data: &'a mut ProgramData,
     mode: &'a dyn Mode,
     debug_infinite_loop: bool,
@@ -82,6 +83,7 @@ pub(super) fn optimizer<'a>(
         },
         changed: false,
         options,
+        mangle_options,
         prepend_stmts: Default::default(),
         append_stmts: Default::default(),
         vars: Default::default(),
@@ -197,6 +199,7 @@ struct Optimizer<'a> {
 
     changed: bool,
     options: &'a CompressOptions,
+    mangle_options: Option<&'a MangleOptions>,
     /// Statements prepended to the current statement.
     prepend_stmts: SynthesizedStmts,
     /// Statements appended to the current statement.

crates/swc_ecma_minifier/src/eval.rs

@@ -87,6 +87,7 @@ impl Evaluator {
                     top_level: Some(TopLevelOptions { functions: true }),
                     ..Default::default()
                 },
+                None,
                 &data,
             ));
         }

crates/swc_ecma_minifier/src/lib.rs

@@ -178,25 +178,30 @@ pub fn optimize(
     if let Some(ref mut t) = timings {
         t.section("compress");
     }
-    if let Some(options) = &options.compress {
+    if let Some(c) = &options.compress {
         {
             let _timer = timer!("compress ast");
 
-            n.visit_mut_with(&mut compressor(marks, options, &Minification))
+            n.visit_mut_with(&mut compressor(
+                marks,
+                c,
+                options.mangle.as_ref(),
+                &Minification,
+            ))
         }
 
         // Again, we don't need to validate ast
 
         let _timer = timer!("postcompress");
 
-        n.visit_mut_with(&mut postcompress_optimizer(options));
+        n.visit_mut_with(&mut postcompress_optimizer(c));
 
         let mut pass = 0;
         loop {
             pass += 1;
 
             let mut v = pure_optimizer(
-                options,
+                c,
                 None,
                 marks,
                 PureOptimizerConfig {
@@ -207,7 +212,7 @@ pub fn optimize(
                 },
             );
             n.visit_mut_with(&mut v);
-            if !v.changed() || options.passes <= pass {
+            if !v.changed() || c.passes <= pass {
                 break;
             }
         }