Don't mix strings with directives in output

 * Don't interpret strings with escaped content as directive
 * Don't interpret strings after empty statement as directive
 * Adapt output to prevent strings being represent as directive
 * Introduce UGLIFY_DEBUG to allow internal testing like EXPECT_DIRECTIVE

2 files changed, 40 insertions, 10 deletions

diff --git a/lib/output.js b/lib/output.js
index 6eae2f1f..1fa9899f 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -43,6 +43,8 @@
 
 "use strict";
 
+var EXPECT_DIRECTIVE = /^$|[;{][\s\n]*$/;
+
 function OutputStream(options) {
 
     options = defaults(options, {
@@ -354,7 +356,18 @@ function OutputStream(options) {
         force_semicolon : force_semicolon,
         to_ascii        : to_ascii,
         print_name      : function(name) { print(make_name(name)) },
-        print_string    : function(str, quote) { print(encode_string(str, quote)) },
+        print_string    : function(str, quote, escape_directive) {
+            var encoded = encode_string(str, quote);
+            if (escape_directive === true && encoded.indexOf("\\") === -1) {
+                // Insert semicolons to break directive prologue
+                if (!EXPECT_DIRECTIVE.test(OUTPUT)) {
+                    force_semicolon();
+                }
+                force_semicolon();
+            }
+            print(encoded);
+        },
+        encode_string   : encode_string,
         next_indent     : next_indent,
         with_indent     : with_indent,
         with_block      : with_block,
@@ -386,6 +399,7 @@ function OutputStream(options) {
     };
 
     var use_asm = false;
+    var in_directive = false;
 
     AST_Node.DEFMETHOD("print", function(stream, force_parens){
         var self = this, generator = self._codegen, prev_use_asm = use_asm;
@@ -642,9 +656,16 @@ function OutputStream(options) {
 
     /* -----[ statements ]----- */
 
-    function display_body(body, is_toplevel, output) {
+    function display_body(body, is_toplevel, output, allow_directives) {
         var last = body.length - 1;
+        in_directive = allow_directives;
         body.forEach(function(stmt, i){
+            if (in_directive === true && !(stmt instanceof AST_Directive ||
+                stmt instanceof AST_EmptyStatement ||
+                (stmt instanceof AST_SimpleStatement && stmt.body instanceof AST_String)
+            )) {
+                in_directive = false;
+            }
             if (!(stmt instanceof AST_EmptyStatement)) {
                 output.indent();
                 stmt.print(output);
@@ -653,7 +674,14 @@ function OutputStream(options) {
                     if (is_toplevel) output.newline();
                 }
             }
+            if (in_directive === true &&
+                stmt instanceof AST_SimpleStatement &&
+                stmt.body instanceof AST_String
+            ) {
+                in_directive = false;
+            }
         });
+        in_directive = false;
     };
 
     AST_StatementWithBody.DEFMETHOD("_do_print_body", function(output){
@@ -665,7 +693,7 @@ function OutputStream(options) {
         output.semicolon();
     });
     DEFPRINT(AST_Toplevel, function(self, output){
-        display_body(self.body, true, output);
+        display_body(self.body, true, output, true);
         output.print("");
     });
     DEFPRINT(AST_LabeledStatement, function(self, output){
@@ -677,9 +705,9 @@ function OutputStream(options) {
         self.body.print(output);
         output.semicolon();
     });
-    function print_bracketed(body, output) {
+    function print_bracketed(body, output, allow_directives) {
         if (body.length > 0) output.with_block(function(){
-            display_body(body, false, output);
+            display_body(body, false, output, allow_directives);
         });
         else output.print("{}");
     };
@@ -779,7 +807,7 @@ function OutputStream(options) {
             });
         });
         output.space();
-        print_bracketed(self.body, output);
+        print_bracketed(self.body, output, true);
     });
     DEFPRINT(AST_Lambda, function(self, output){
         self._do_print(output);
@@ -1185,7 +1213,7 @@ function OutputStream(options) {
         output.print(self.getValue());
     });
     DEFPRINT(AST_String, function(self, output){
-        output.print_string(self.getValue(), self.quote);
+        output.print_string(self.getValue(), self.quote, in_directive);
     });
     DEFPRINT(AST_Number, function(self, output){
         if (use_asm && self.start.raw != null) {
diff --git a/lib/parse.js b/lib/parse.js
index 2c007965..9b5a142b 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -815,9 +815,10 @@ function parse($TEXT, options) {
         handle_regexp();
         switch (S.token.type) {
           case "string":
-            if (S.in_directives) {
-                if (is_token(peek(), "punc", ";") || peek().nlb) {
-                    S.input.add_directive(S.token.raw.substr(1, S.token.raw.length - 2));
+            var dir = false;
+            if (S.in_directives === true) {
+                if ((is_token(peek(), "punc", ";") || peek().nlb) && S.token.raw.indexOf("\\") === -1) {
+                    S.input.add_directive(S.token.value);
                 } else {
                     S.in_directives = false;
                 }
@@ -855,6 +856,7 @@ function parse($TEXT, options) {
               case "(":
                 return simple_statement();
               case ";":
+                S.in_directives = false;
                 next();
                 return new AST_EmptyStatement();
               default: