fix corner cases with `export` (#4699)

fixes #4698
fixes #4700
fixes #4701
fixes #4702

2 files changed, 10 insertions, 7 deletions

diff --git a/lib/output.js b/lib/output.js
index bebcd7fd..ff05356e 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -662,12 +662,15 @@ function OutputStream(options) {
     // a function expression needs parens around it when it's provably
     // the first token to appear in a statement.
     function needs_parens_function(output) {
-        if (!output.has_parens() && first_in_statement(output)) return true;
         var p = output.parent();
-        // export default (function foo() {});
-        if (this.name && p instanceof AST_ExportDefault) return true;
-        // export default (function() {})(foo);
-        if (p && p.TYPE == "Call" && output.parent(1) instanceof AST_ExportDefault) return true;
+        if (!output.has_parens() && first_in_statement(output, false, true)) {
+            // export default function() {}
+            // export default (function foo() {});
+            // export default (function() {})(foo);
+            // export default (function() {})`foo`;
+            // export default (function() {}) ? foo : bar;
+            return this.name || !(p instanceof AST_ExportDefault);
+        }
         if (output.option("webkit") && p instanceof AST_PropAccess && p.expression === this) return true;
         if (output.option("wrap_iife") && p instanceof AST_Call && p.expression === this) return true;
     }
diff --git a/lib/utils.js b/lib/utils.js
index f9c78431..28c8b43e 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -238,7 +238,7 @@ function HOP(obj, prop) {
 // return true if the node at the top of the stack (that means the
 // innermost node in the current output) is lexically the first in
 // a statement.
-function first_in_statement(stack, arrow) {
+function first_in_statement(stack, arrow, export_default) {
     var node = stack.parent(-1);
     for (var i = 0, p; p = stack.parent(i++); node = p) {
         if (is_arrow(p)) {
@@ -250,7 +250,7 @@ function first_in_statement(stack, arrow) {
         } else if (p instanceof AST_Conditional) {
             if (p.condition === node) continue;
         } else if (p instanceof AST_ExportDefault) {
-            return false;
+            return export_default;
         } else if (p instanceof AST_PropAccess) {
             if (p.expression === node) continue;
         } else if (p instanceof AST_Sequence) {