Tolerate unescaped newlines in string literals

Author: Martin Jambon

grammar.js

@@ -61,6 +61,7 @@ module.exports = grammar({
     $._jsx_attribute_value,
     $._jsx_identifier,
     $._lhs_expression,
+    $._string,
   ],
 
   conflicts: $ => [
@@ -568,7 +569,7 @@ module.exports = grammar({
     ),
 
     _jsx_attribute_value: $ => choice(
-      $.string,
+      $.jsx_string,
       $.jsx_expression,
       $._jsx_element,
       $.jsx_fragment
@@ -804,25 +805,34 @@ module.exports = grammar({
     // Primitives
     //
 
-    string: $ => choice(
+    // Here we tolerate unescaped newlines in double-quoted and
+    // single-quoted string literals.
+    // This is legal in typescript as jsx/tsx attribute values (as of
+    // 2020), and perhaps will be valid in javascript as well in the
+    // future.
+    //
+    _string: $ => choice(
       seq(
         '"',
         repeat(choice(
-          token.immediate(prec(PREC.STRING, /[^"\\\n]+|\\\r?\n/)),
+          token.immediate(prec(PREC.STRING, /[^"\\\n]+|\\?\r?\n/)),
           $.escape_sequence
         )),
         '"'
       ),
       seq(
         "'",
         repeat(choice(
-          token.immediate(prec(PREC.STRING, /[^'\\\n]+|\\\r?\n/)),
+          token.immediate(prec(PREC.STRING, /[^'\\\n]+|\\?\r?\n/)),
           $.escape_sequence
         )),
         "'"
       )
     ),
 
+    string: $ => $._string,
+    jsx_string: $ => $._string,
+
     escape_sequence: $ => token.immediate(seq(
       '\\',
       choice(

src/grammar.json

@@ -2337,7 +2337,7 @@
       "members": [
         {
           "type": "SYMBOL",
-          "name": "string"
+          "name": "jsx_string"
         },
         {
           "type": "SYMBOL",
@@ -4411,7 +4411,7 @@
         ]
       }
     },
-    "string": {
+    "_string": {
       "type": "CHOICE",
       "members": [
         {
@@ -4433,7 +4433,7 @@
                       "value": 2,
                       "content": {
                         "type": "PATTERN",
-                        "value": "[^\"\\\\\\n]+|\\\\\\r?\\n"
+                        "value": "[^\"\\\\\\n]+|\\\\?\\r?\\n"
                       }
                     }
                   },
@@ -4469,7 +4469,7 @@
                       "value": 2,
                       "content": {
                         "type": "PATTERN",
-                        "value": "[^'\\\\\\n]+|\\\\\\r?\\n"
+                        "value": "[^'\\\\\\n]+|\\\\?\\r?\\n"
                       }
                     }
                   },
@@ -4488,6 +4488,14 @@
         }
       ]
     },
+    "string": {
+      "type": "SYMBOL",
+      "name": "_string"
+    },
+    "jsx_string": {
+      "type": "SYMBOL",
+      "name": "_string"
+    },
     "escape_sequence": {
       "type": "IMMEDIATE_TOKEN",
       "content": {
@@ -5981,7 +5989,8 @@
     "_jsx_attribute_name",
     "_jsx_attribute_value",
     "_jsx_identifier",
-    "_lhs_expression"
+    "_lhs_expression",
+    "_string"
   ],
   "supertypes": [
     "_statement",

src/node-types.json

@@ -1488,11 +1488,11 @@
           "named": true
         },
         {
-          "type": "property_identifier",
+          "type": "jsx_string",
           "named": true
         },
         {
-          "type": "string",
+          "type": "property_identifier",
           "named": true
         }
       ]
@@ -1719,6 +1719,21 @@
       }
     }
   },
+  {
+    "type": "jsx_string",
+    "named": true,
+    "fields": {},
+    "children": {
+      "multiple": true,
+      "required": false,
+      "types": [
+        {
+          "type": "escape_sequence",
+          "named": true
+        }
+      ]
+    }
+  },
   {
     "type": "labeled_statement",
     "named": true,