[llvm] [llvm-lit] Support curly brace syntax in lit internal shell (PR #102830)

[Paul Kirth via llvm-commits]

================
@@ -255,18 +261,42 @@ def parse_pipeline(self):
             self.lex()
             commands.append(self.parse_command())
         return Pipeline(commands, negate, self.pipefail)
+            
+    
+    # {echo foo; echo bar;} && echo hello
+    # echo hello && {echo foo; echo bar}
+    
+    def parse(self, seq_type):
+        lhs = None
+        if isinstance(self.look(), tuple):
+            brace = self.lex()
+            self.brace_stack.append(brace)
+            if brace[0] == '{':
+                lhs = self.parse(('{', '}'))
+            else:
+                raise ValueError("syntax error near unexpected token %r" % brace[0])
 
-    def parse(self):
-        lhs = self.parse_pipeline()
+        else:
+            lhs = self.parse_pipeline()
 
         while self.look():
             operator = self.lex()
             assert isinstance(operator, tuple) and len(operator) == 1
 
+            if operator == self.brace_dict[self.brace_stack.peek()]:
+                break
+
             if not self.look():
                 raise ValueError("missing argument to operator %r" % operator[0])
 
             # FIXME: Operator precedence!!
-            lhs = Seq(lhs, operator[0], self.parse_pipeline())
+            if isinstance(self.look(), tuple):
+                lhs = self.parse(('{', '}'))
+            else: 
+                lhs = Seq(lhs, operator[0], self.parse_pipeline(), seq_type)
+            seq_type = None
----------------
ilovepi wrote:

Why is the `seq_type` thrown away?

https://github.com/llvm/llvm-project/pull/102830