[CS2] Fix non-bare `get` `set` when called with `@` argument (#4525)

* Fixes #4524: `get` and `set` should be usable without parentheses when accessed via a period

* More get/set tests

lib/coffeescript/lexer.js

@@ -135,7 +135,7 @@
           this.error(`'${prev[1]}' cannot be used as a keyword, or as a function call without parentheses`, prev[2]);
         } else {
           prevprev = this.tokens[this.tokens.length - 2];
-          if (((ref7 = prev[0]) === '@' || ref7 === 'THIS') && prevprev && prevprev.spaced && /^[gs]et$/.test(prevprev[1])) {
+          if (((ref7 = prev[0]) === '@' || ref7 === 'THIS') && prevprev && prevprev.spaced && /^[gs]et$/.test(prevprev[1]) && this.tokens[this.tokens.length - 3][0] !== '.') {
             this.error(`'${prevprev[1]}' cannot be used as a keyword, or as a function call without parentheses`, prevprev[2]);
           }
         }

src/lexer.coffee

@@ -179,7 +179,8 @@ exports.Lexer = class Lexer
         @error "'#{prev[1]}' cannot be used as a keyword, or as a function call without parentheses", prev[2]
       else
         prevprev = @tokens[@tokens.length - 2]
-        if prev[0] in ['@', 'THIS'] and prevprev and prevprev.spaced and /^[gs]et$/.test(prevprev[1])
+        if prev[0] in ['@', 'THIS'] and prevprev and prevprev.spaced and /^[gs]et$/.test(prevprev[1]) and
+        @tokens[@tokens.length - 3][0] isnt '.'
           @error "'#{prevprev[1]}' cannot be used as a keyword, or as a function call without parentheses", prevprev[2]
 
     if tag is 'IDENTIFIER' and id in RESERVED

test/function_invocation.coffee

@@ -714,13 +714,26 @@ test "get and set can be used as function names when not ambiguous with `get`/`s
   eq 3, set(3)
   eq 'a', get('a')
   eq 'b', set('b')
+  eq 4, get 4
+  eq 5, set 5
+  eq 'c', get 'c'
+  eq 'd', set 'd'
+
+  @get = get
+  @set = set
+  eq 6, @get 6
+  eq 7, @set 7
 
   get = ({val}) -> val
   set = ({val}) -> val
-  eq 4, get({val: 4})
-  eq 5, set({val: 5})
-  eq 'c', get({val: 'c'})
-  eq 'd', set({val: 'd'})
+  eq 8, get({val: 8})
+  eq 9, set({val: 9})
+  eq 'e', get({val: 'e'})
+  eq 'f', set({val: 'f'})
+  eq 10, get {val: 10}
+  eq 11, set {val: 11}
+  eq 'g', get {val: 'g'}
+  eq 'h', set {val: 'h'}
 
 test "get and set can be used as variable and property names", ->
   get = 2
@@ -748,3 +761,34 @@ test "get and set can be used as class method names", ->
 
   eq 4, B.get()
   eq 5, B.set()
+
+test "functions named get or set can be used without parentheses when attached to an object; #4524", ->
+  obj =
+    get: (x) -> x + 2
+    set: (x) -> x + 3
+
+  class A
+    get: (x) -> x + 4
+    set: (x) -> x + 5
+
+  a = new A()
+
+  eq 12, obj.get 10
+  eq 13, obj.set 10
+
+  eq 14, a.get 10
+  eq 15, a.set 10
+
+  @ten = 10
+
+  eq 12, obj.get @ten
+  eq 13, obj.set @ten
+
+  eq 14, a.get @ten
+  eq 15, a.set @ten
+
+  obj.obj = obj
+
+  eq 12, obj.obj.get @ten
+  eq 13, obj.obj.set @ten
+