xdrgen: Improve parse error reporting

The current verbose Lark exception output makes it difficult to
quickly identify and fix syntax errors in XDR specifications. Users
must wade through hundreds of lines of cascading errors to find the
root cause.

Replace this with concise, compiler-style error messages showing
file, line, column, the unexpected token, and the source line with
a caret pointing to the error location.

Before:
  Unexpected token Token('__ANON_1', '+1') at line 14, column 35.
  Expected one of:
          * SEMICOLON
  Previous tokens: [Token('__ANON_0', 'LM_MAXSTRLEN')]
  [hundreds more cascading errors...]

After:
  file.x:14:35: parse error
  Unexpected number '+1'

      const LM_MAXNAMELEN = LM_MAXSTRLEN+1;
                                        ^

The error handler now raises XdrParseError on the first error,
preventing cascading messages that obscure the root cause.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/tools/net/sunrpc/xdrgen/subcmds/source.py b/tools/net/sunrpc/xdrgen/subcmds/source.py
index 2024954748f0..bc7d38802df3 100644
--- a/tools/net/sunrpc/xdrgen/subcmds/source.py
+++ b/tools/net/sunrpc/xdrgen/subcmds/source.py
@@ -8,7 +8,6 @@ import logging
 
 from argparse import Namespace
 from lark import logger
-from lark.exceptions import UnexpectedInput
 
 from generators.source_top import XdrSourceTopGenerator
 from generators.enum import XdrEnumGenerator
@@ -23,6 +22,7 @@ from xdr_ast import _XdrAst, _XdrEnum, _XdrPointer
 from xdr_ast import _XdrStruct, _XdrTypedef, _XdrUnion
 
 from xdr_parse import xdr_parser, set_xdr_annotate
+from xdr_parse import make_error_handler, XdrParseError
 
 logger.setLevel(logging.INFO)
 
@@ -92,19 +92,19 @@ def generate_client_source(filename: str, root: Specification, language: str) ->
     # cel: todo: client needs PROC macros
 
 
-def handle_parse_error(e: UnexpectedInput) -> bool:
-    """Simple parse error reporting, no recovery attempted"""
-    print(e)
-    return True
-
-
 def subcmd(args: Namespace) -> int:
     """Generate encoder and decoder functions"""
 
     set_xdr_annotate(args.annotate)
     parser = xdr_parser()
     with open(args.filename, encoding="utf-8") as f:
-        parse_tree = parser.parse(f.read(), on_error=handle_parse_error)
+        source = f.read()
+        try:
+            parse_tree = parser.parse(
+                source, on_error=make_error_handler(source, args.filename)
+            )
+        except XdrParseError:
+            return 1
         ast = transform_parse_tree(parse_tree)
         match args.peer:
             case "server":