[lit] Update internal shell lexer to handle LLDB persistent vars.

llvm/utils/lit/lit/ShUtil.py

@@ -115,6 +115,11 @@ def lex_arg_quoted(self, delim):
             c = self.eat()
             if c == delim:
                 return str
+            # LLDB uses "$" at the start of global variable names; it should
+            # not be escaped nor dropped.
+            elif c == "\\" and self.look() == "$":
+                c = self.eat()
+                str += c
             elif c == "\\" and delim == '"':
                 # Inside a '"' quoted string, '\\' only escapes the quote
                 # character and backslash, otherwise it is preserved.

llvm/utils/lit/tests/unit/ShUtil.py

@@ -28,7 +28,8 @@ def test_quoting(self):
         self.assertEqual(self.lex(""" a\\ b a\\\\b """), ["a b", "a\\b"])
         self.assertEqual(self.lex(""" "" "" """), ["", ""])
         self.assertEqual(self.lex(""" a\\ b """, win32Escapes=True), ["a\\", "b"])
-
+        self.assertEqual(self.lex('"\\$y = 11"'), ["$y = 11"])
+        self.assertEqual(self.lex('"expr \\$y = 11"'), ["expr $y = 11"])
 
 class TestShParse(unittest.TestCase):
     def parse(self, str):