avoid collision with HTML comments (#3625)

fixes #3624

2 files changed, 82 insertions, 49 deletions

diff --git a/lib/output.js b/lib/output.js
index 0f8ef1cd..d97778b2 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -269,7 +269,7 @@ function OutputStream(options) {
             }
         }
         newline_insert = -1;
-        var prev = last.charAt(last.length - 1);
+        var prev = last.slice(-1);
         if (might_need_semicolon) {
             might_need_semicolon = false;
 
@@ -298,16 +298,16 @@ function OutputStream(options) {
         }
 
         if (might_need_space) {
-            if ((is_identifier_char(prev)
-                    && (is_identifier_char(ch) || ch == "\\"))
+            if (is_identifier_char(prev) && (is_identifier_char(ch) || ch == "\\")
                 || (ch == "/" && ch == prev)
-                || ((ch == "+" || ch == "-") && ch == last))
-            {
+                || ((ch == "+" || ch == "-") && ch == last)
+                || str == "--" && last == "!"
+                || last == "--" && ch == ">") {
                 OUTPUT += " ";
                 current_col++;
                 current_pos++;
             }
-            might_need_space = false;
+            if (prev != "<" || str != "!") might_need_space = false;
         }
 
         if (mapping_token) {
@@ -322,7 +322,7 @@ function OutputStream(options) {
         }
 
         OUTPUT += str;
-        has_parens = str[str.length - 1] == "(";
+        has_parens = str.slice(-1) == "(";
         current_pos += str.length;
         var a = str.split(/\r?\n/), n = a.length - 1;
         current_line += n;
@@ -1254,29 +1254,10 @@ function OutputStream(options) {
         output.print(self.operator);
     });
     DEFPRINT(AST_Binary, function(self, output) {
-        var op = self.operator;
         self.left.print(output);
-        if (op[0] == ">" /* ">>" ">>>" ">" ">=" */
-            && self.left instanceof AST_UnaryPostfix
-            && self.left.operator == "--") {
-            // space is mandatory to avoid outputting -->
-            output.print(" ");
-        } else {
-            // the space is optional depending on "beautify"
-            output.space();
-        }
-        output.print(op);
-        if ((op == "<" || op == "<<")
-            && self.right instanceof AST_UnaryPrefix
-            && self.right.operator == "!"
-            && self.right.expression instanceof AST_UnaryPrefix
-            && self.right.expression.operator == "--") {
-            // space is mandatory to avoid outputting <!--
-            output.print(" ");
-        } else {
-            // the space is optional depending on "beautify"
-            output.space();
-        }
+        output.space();
+        output.print(self.operator);
+        output.space();
         self.right.print(output);
     });
     DEFPRINT(AST_Conditional, function(self, output) {
diff --git a/test/compress/html_comments.js b/test/compress/html_comments.js
index fe6ff8ac..e208b36d 100644
--- a/test/compress/html_comments.js
+++ b/test/compress/html_comments.js
@@ -1,55 +1,107 @@
 html_comment_in_expression: {
     input: {
-        function f(a, b, x, y) { return a < !--b && x-- > y; }
+        (function(a, b) {
+            console.log(a < !--b && a-- > b, a, b);
+        })(1, 2);
     }
-    expect_exact: "function f(a,b,x,y){return a< !--b&&x-- >y}";
+    expect_exact: "(function(a,b){console.log(a<! --b&&a-- >b,a,b)})(1,2);"
+    expect_stdout: "false 1 1"
 }
 
 html_comment_in_less_than: {
     input: {
-        function f(a, b) { return a < !--b; }
+        (function(a, b, c) {
+            console.log(
+                a < !--b,
+                a < !--b + c,
+                a + b < !--c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a< !--b}";
+    expect_exact: "(function(a,b,c){console.log(a<! --b,a<! --b+c,a+b<! --c,a,b,c)})(1,2,3);"
+    expect_stdout: "false true false 1 0 2"
 }
 
 html_comment_in_left_shift: {
     input: {
-        function f(a, b) { return a << !--b; }
+        (function(a, b, c) {
+            console.log(
+                a << !--b,
+                a << !--b + c,
+                a + b << !--c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a<< !--b}";
+    expect_exact: "(function(a,b,c){console.log(a<<! --b,a<<! --b+c,a+b<<! --c,a,b,c)})(1,2,3);"
+    expect_stdout: "1 16 1 1 0 2"
 }
 
-html_comment_in_right_shift: {
+html_comment_in_greater_than: {
     input: {
-        function f(a, b) { return a-- >> b; }
+        (function(a, b, c) {
+            console.log(
+                a-- > b,
+                a-- > b + c,
+                a + b-- > c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a-- >>b}";
+    expect_exact: "(function(a,b,c){console.log(a-- >b,a-- >b+c,a+b-- >c,a,b,c)})(1,2,3);"
+    expect_stdout: "false false false -1 1 3"
 }
 
-html_comment_in_zero_fill_right_shift: {
+html_comment_in_greater_than_or_equal: {
     input: {
-        function f(a, b) { return a-- >>> b; }
+        (function(a, b, c) {
+            console.log(
+                a-- >= b,
+                a-- >= b + c,
+                a + b-- >= c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a-- >>>b}";
+    expect_exact: "(function(a,b,c){console.log(a-- >=b,a-- >=b+c,a+b-- >=c,a,b,c)})(1,2,3);"
+    expect_stdout: "false false false -1 1 3"
 }
 
-html_comment_in_greater_than: {
+html_comment_in_right_shift: {
     input: {
-        function f(a, b) { return a-- > b; }
+        (function(a, b, c) {
+            console.log(
+                a-- >> b,
+                a-- >> b + c,
+                a + b-- >> c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a-- >b}";
+    expect_exact: "(function(a,b,c){console.log(a-- >>b,a-- >>b+c,a+b-- >>c,a,b,c)})(1,2,3);"
+    expect_stdout: "0 0 0 -1 1 3"
 }
 
-html_comment_in_greater_than_or_equal: {
+html_comment_in_zero_fill_right_shift: {
     input: {
-        function f(a, b) { return a-- >= b; }
+        (function(a, b, c) {
+            console.log(
+                a-- >>> b,
+                a-- >>> b + c,
+                a + b-- >>> c,
+                a, b, c
+            );
+        })(1, 2, 3);
     }
-    expect_exact: "function f(a,b){return a-- >=b}";
+    expect_exact: "(function(a,b,c){console.log(a-- >>>b,a-- >>>b+c,a+b-- >>>c,a,b,c)})(1,2,3);"
+    expect_stdout: "0 0 0 -1 1 3"
 }
 
 html_comment_in_string_literal: {
     input: {
-        function f() { return "<!--HTML-->comment in<!--string literal-->"; }
+        console.log("<!--HTML-->comment in<!--string literal-->".length);
     }
-    expect_exact: 'function f(){return"\\x3c!--HTML--\\x3ecomment in\\x3c!--string literal--\\x3e"}';
+    expect_exact: 'console.log("\\x3c!--HTML--\\x3ecomment in\\x3c!--string literal--\\x3e".length);'
+    expect_stdout: "42"
 }