print "__PURE__" comments when not minifying (#221)

evanw · Jul 6, 2020 · b96fc64 · b96fc64
1 parent bfaf350
commit b96fc64
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Showing 2 changed files with 35 additions and 14 deletions.
diff --git a/internal/bundler/bundler_dce_test.go b/internal/bundler/bundler_dce_test.go
@@ -816,24 +816,24 @@ func TestRemoveUnusedPureCommentCalls(t *testing.T) {
 function bar() {
 }
 let bare = foo(bar);
-let at_no = foo(bar());
-let new_at_no = new foo(bar());
-let num_no = foo(bar());
-let new_num_no = new foo(bar());
-let dot_no = foo(sideEffect()).dot(bar());
-let new_dot_no = new foo(sideEffect()).dot(bar());
-let nested_no = [1, foo(bar()), 2];
-let new_nested_no = [1, new foo(bar()), 2];
-let single_at_no = foo(bar());
-let new_single_at_no = new foo(bar());
-let single_num_no = foo(bar());
-let new_single_num_no = new foo(bar());
+let at_no = /* @__PURE__ */ foo(bar());
+let new_at_no = /* @__PURE__ */ new foo(bar());
+let num_no = /* @__PURE__ */ foo(bar());
+let new_num_no = /* @__PURE__ */ new foo(bar());
+let dot_no = /* @__PURE__ */ foo(sideEffect()).dot(bar());
+let new_dot_no = /* @__PURE__ */ new foo(sideEffect()).dot(bar());
+let nested_no = [1, /* @__PURE__ */ foo(bar()), 2];
+let new_nested_no = [1, /* @__PURE__ */ new foo(bar()), 2];
+let single_at_no = /* @__PURE__ */ foo(bar());
+let new_single_at_no = /* @__PURE__ */ new foo(bar());
+let single_num_no = /* @__PURE__ */ foo(bar());
+let new_single_num_no = /* @__PURE__ */ new foo(bar());
 let bad_no = foo(bar);
 let new_bad_no = new foo(bar);
 let parens_no = foo(bar);
 let new_parens_no = new foo(bar);
-let exp_no = foo() ** foo();
-let new_exp_no = new foo() ** foo();
+let exp_no = /* @__PURE__ */ foo() ** foo();
+let new_exp_no = /* @__PURE__ */ new foo() ** foo();
 `,
  },
  })

diff --git a/internal/printer/printer.go b/internal/printer/printer.go
@@ -1140,9 +1140,20 @@ func (p *printer) printExpr(expr ast.Expr, level ast.L, flags int) {
 
  case *ast.ENew:
  wrap := level >= ast.LCall
+
+ hasPureComment := !p.options.RemoveWhitespace && e.CanBeUnwrappedIfUnused
+ if hasPureComment && level >= ast.LPostfix {
+ wrap = true
+ }
+
  if wrap {
  p.print("(")
  }
+
+ if hasPureComment {
+ p.print("/* @__PURE__ */ ")
+ }
+
  p.printSpaceBeforeIdentifier()
  p.print("new")
  p.printSpace()
@@ -1171,10 +1182,20 @@ func (p *printer) printExpr(expr ast.Expr, level ast.L, flags int) {
  } else if (flags & hasNonOptionalChainParent) != 0 {
  wrap = true
  }
+
+ hasPureComment := !p.options.RemoveWhitespace && e.CanBeUnwrappedIfUnused
+ if hasPureComment && level >= ast.LPostfix {
+ wrap = true
+ }
+
  if wrap {
  p.print("(")
  }
 
+ if hasPureComment {
+ p.print("/* @__PURE__ */ ")
+ }
+
  // We don't ever want to accidentally generate a direct eval expression here
  if !e.IsDirectEval && p.isUnboundEvalIdentifier(e.Target) {
  if p.options.RemoveWhitespace {