Commit 63a5425f authored by Chuck Lever's avatar Chuck Lever
Browse files

xdrgen: Extend error reporting to AST transformation phase 



Commit 277df18d7df9 ("xdrgen: Improve parse error reporting") added
clean, compiler-style error messages for syntax errors detected during
parsing. However, semantic errors discovered during AST transformation
still produce verbose Python stack traces.

When an XDR specification references an undefined type, the transformer
raises a VisitError wrapping a KeyError. Before this change:

  Traceback (most recent call last):
    File ".../lark/visitors.py", line 124, in _call_userfunc
      return f(children)
    ...
  KeyError: 'fsh4_mode'
  ...
  lark.exceptions.VisitError: Error trying to process rule "basic":
  'fsh4_mode'

After this change:

  file.x:156:2: semantic error
  Undefined type 'fsh4_mode'

      	fsh4_mode	mode;
              ^

The new handle_transform_error() function extracts position information
from the Lark tree node metadata and formats the error consistently with
parse error messages.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 3e6397b0

tools/net/sunrpc/xdrgen/subcmds/declarations.py

+7 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import VisitError



from generators.constant import XdrConstantGenerator

from generators.enum import XdrEnumGenerator
@@ -24,6 +25,7 @@ from xdr_ast import _XdrConstant, _XdrEnum, _XdrPointer 
from xdr_ast import _XdrTypedef, _XdrStruct, _XdrUnion

from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError

from xdr_parse import handle_transform_error



logger.setLevel(logging.INFO)
@@ -63,7 +65,11 @@ def subcmd(args: Namespace) -> int: 
            )

        except XdrParseError:

            return 1

        try:

            ast = transform_parse_tree(parse_tree)

        except VisitError as e:

            handle_transform_error(e, source, args.filename)

            return 1



        gen = XdrHeaderTopGenerator(args.language, args.peer)

        gen.emit_declaration(args.filename, ast)

tools/net/sunrpc/xdrgen/subcmds/definitions.py

+7 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import VisitError



from generators.constant import XdrConstantGenerator

from generators.enum import XdrEnumGenerator
@@ -24,6 +25,7 @@ from xdr_ast import _RpcProgram, _XdrConstant, _XdrEnum, _XdrPointer 
from xdr_ast import _XdrTypedef, _XdrStruct, _XdrUnion

from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError

from xdr_parse import handle_transform_error



logger.setLevel(logging.INFO)
@@ -82,7 +84,11 @@ def subcmd(args: Namespace) -> int: 
            )

        except XdrParseError:

            return 1

        try:

            ast = transform_parse_tree(parse_tree)

        except VisitError as e:

            handle_transform_error(e, source, args.filename)

            return 1



        gen = XdrHeaderTopGenerator(args.language, args.peer)

        gen.emit_definition(args.filename, ast)

tools/net/sunrpc/xdrgen/subcmds/lint.py

+7 −1
Original line number Diff line number Diff line
@@ -8,8 +8,10 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import VisitError



from xdr_parse import xdr_parser, make_error_handler, XdrParseError

from xdr_parse import handle_transform_error

from xdr_ast import transform_parse_tree



logger.setLevel(logging.DEBUG)
@@ -27,6 +29,10 @@ def subcmd(args: Namespace) -> int: 
            )

        except XdrParseError:

            return 1

        try:

            transform_parse_tree(parse_tree)

        except VisitError as e:

            handle_transform_error(e, source, args.filename)

            return 1



    return 0

tools/net/sunrpc/xdrgen/subcmds/source.py

+7 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ import logging 


from argparse import Namespace

from lark import logger

from lark.exceptions import VisitError



from generators.source_top import XdrSourceTopGenerator

from generators.enum import XdrEnumGenerator
@@ -23,6 +24,7 @@ from xdr_ast import _XdrStruct, _XdrTypedef, _XdrUnion 


from xdr_parse import xdr_parser, set_xdr_annotate

from xdr_parse import make_error_handler, XdrParseError

from xdr_parse import handle_transform_error



logger.setLevel(logging.INFO)
@@ -105,7 +107,11 @@ def subcmd(args: Namespace) -> int: 
            )

        except XdrParseError:

            return 1

        try:

            ast = transform_parse_tree(parse_tree)

        except VisitError as e:

            handle_transform_error(e, source, args.filename)

            return 1

        match args.peer:

            case "server":

                generate_server_source(args.filename, ast, args.language)

tools/net/sunrpc/xdrgen/xdr_parse.py

+39 −1
Original line number Diff line number Diff line
@@ -7,7 +7,7 @@ import sys 
from typing import Callable



from lark import Lark

from lark.exceptions import UnexpectedInput, UnexpectedToken

from lark.exceptions import UnexpectedInput, UnexpectedToken, VisitError





# Set to True to emit annotation comments in generated source
@@ -107,6 +107,44 @@ def make_error_handler(source: str, filename: str) -> Callable[[UnexpectedInput] 
    return handle_parse_error





def handle_transform_error(e: VisitError, source: str, filename: str) -> None:

    """Report a transform error with context.



    Args:

        e: The VisitError from Lark's transformer

        source: The XDR source text being parsed

        filename: The name of the file being parsed

    """

    lines = source.splitlines()



    # Extract position from the tree node if available

    line_num = 0

    column = 0

    if hasattr(e.obj, "meta") and e.obj.meta:

        line_num = e.obj.meta.line

        column = e.obj.meta.column



    line_text = lines[line_num - 1] if 0 < line_num <= len(lines) else ""



    # Build the error message

    msg_parts = [f"{filename}:{line_num}:{column}: semantic error"]



    # The original exception is typically a KeyError for undefined types

    if isinstance(e.orig_exc, KeyError):

        msg_parts.append(f"Undefined type '{e.orig_exc.args[0]}'")

    else:

        msg_parts.append(str(e.orig_exc))



    # Show the offending line with a caret pointing to the error

    if line_text:

        msg_parts.append("")

        msg_parts.append(f"    {line_text}")

        prefix = line_text[: column - 1].expandtabs()

        msg_parts.append(f"    {' ' * len(prefix)}^")



    sys.stderr.write("\n".join(msg_parts) + "\n")





def xdr_parser() -> Lark:

    """Return a Lark parser instance configured with the XDR language grammar"""