Merge pull request #4383 from GeoffreyBooth/escape-template-literals

Escape backticks and `${` within template literals; fixes #4380

Author: lydell

lib/coffee-script/nodes.js

@@ -2274,7 +2274,14 @@ exports.StringWithInterpolations = class StringWithInterpolations extends Parens
     fragments.push @makeCode '`'
     for element in elements
       if element instanceof StringLiteral
-        fragments.push @makeCode element.value.slice(1, -1)
+        value = element.value[1...-1]
+        # Backticks and `${` inside template literals must be escaped.
+        value = value.replace /(\\*)(`|\$\{)/g, (match, backslashes, toBeEscaped) ->
+          if backslashes.length % 2 is 0
+            "#{backslashes}\\#{toBeEscaped}"
+          else
+            match
+        fragments.push @makeCode value
       else
         fragments.push @makeCode '${'
         fragments.push element.compileToFragments(o, LEVEL_PAREN)...

src/nodes.coffee

@@ -137,3 +137,35 @@ test "tagged template literal with an interpolated string that itself contains a
 test "tagged template literal with an interpolated string that contains a tagged template literal", ->
   eq 'text: [inner tagged | literal] expressions: [text: [|] expressions: [template]]',
   func"inner tagged #{func"#{'template'}"} literal"
+
+test "tagged template literal with backticks", ->
+  eq 'text: [ES template literals look like this: `foo bar`] expressions: []',
+  func"ES template literals look like this: `foo bar`"
+
+test "tagged template literal with escaped backticks", ->
+  eq 'text: [ES template literals look like this: \\`foo bar\\`] expressions: []',
+  func"ES template literals look like this: \\`foo bar\\`"
+
+test "tagged template literal with unnecessarily escaped backticks", ->
+  eq 'text: [ES template literals look like this: `foo bar`] expressions: []',
+  func"ES template literals look like this: \`foo bar\`"
+
+test "tagged template literal with ES interpolation", ->
+  eq 'text: [ES template literals also look like this: `3 + 5 = ${3+5}`] expressions: []',
+  func"ES template literals also look like this: `3 + 5 = ${3+5}`"
+
+test "tagged template literal with both ES and CoffeeScript interpolation", ->
+  eq "text: [ES template literals also look like this: `3 + 5 = ${3+5}` which equals |] expressions: [8]",
+  func"ES template literals also look like this: `3 + 5 = ${3+5}` which equals #{3+5}"
+
+test "tagged template literal with escaped ES interpolation", ->
+  eq 'text: [ES template literals also look like this: `3 + 5 = \\${3+5}`] expressions: []',
+  func"ES template literals also look like this: `3 + 5 = \\${3+5}`"
+
+test "tagged template literal with unnecessarily escaped ES interpolation", ->
+  eq 'text: [ES template literals also look like this: `3 + 5 = ${3+5}`] expressions: []',
+  func"ES template literals also look like this: `3 + 5 = \${3+5}`"
+
+test "tagged template literal special escaping", ->
+  eq 'text: [` ` \\` \\` \\\\` $ { ${ ${ \\${ \\${ \\\\${ | ` ${] expressions: [1]',
+  func"` \` \\` \\\` \\\\` $ { ${ \${ \\${ \\\${ \\\\${ #{1} ` ${"