tools: fix regex strings in Python tools

[josusky]

tools: fix regex strings in Python tools

Strings used to construct regular expressions shall be marked as raw
otherwise newer versions of Python throw "SyntaxError" because of
invalid escape sequences.

[nodejs-github-bot]

Review requested:

• @nodejs/v8-update

[cjihrig]

Changes in deps/v8 need to be upstreamed to the V8 project first.

[josusky]

OK, so please upstream it, whatever it means ;-)
I am sorry, I am new to nodejs, and I have no idea about the relation to the v8 project. I have just spotted a trivial bug so I have fixed it.

[Trott]

@nodejs/python

[MoLow]

OK, so please upstream it, whatever it means ;-) I am sorry, I am new to nodejs, and I have no idea about the relation to the v8 project. I have just spotted a trivial bug so I have fixed it.

@josusky thanks for this contribution, the meaning is you need to get the change into v8 (following their contribution guide), then if the change is accepted it will automatically be pulled into node

[Trott]

@josusky thanks for this contribution, the meaning is you need to get the change into v8 (following their contribution guide), then if the change is accepted it will automatically be pulled into node

For clarity: That only applies to the change to deps/v8/tools/gen-postmortem-metadata.py. The changes in the other three files can be submitted in this PR.

[cclauss]

I do not understand the reason for this pull request. Regex loves raw strings in Python. They are recommended in Python docs.

The solution is to use Python’s raw string notation for regular expressions; backslashes are not handled in any special way in a string literal prefixed with 'r', so r"\n" is a two-character string containing '' and 'n', while "\n" is a one-character string containing a newline. Regular expressions will often be written in Python code using this raw string notation. https://docs.python.org/3/howto/regex.html#the-backslash-plague

Why change from one string to another If two strings are equal to each other?
% python3

>>> r'\s*=.*' == '\s*=.*'
True
>>> r'\\s*=.*' == '\\s*=.*'
False

Please provide example code and a stack trace for where each of these raw strings generates a Python SyntaxError.

[cclauss]

Please provide example code and a stack trace for where each of these raw strings generates a Python SyntaxError.

[josusky]

The point is that in your code you sometimes do not use raw strings. Just look at the code that I have changed. If your python is old enough or not set to report all errors you may not notice the problem, but sooner or later, the deprecated constructions like '\s' will stop working. Just try the following code:

test_string = '\s'

and run it like this python3 -Werror test.py

  File "/home/jano/test.py", line 1
    test_string = '\s'
                  ^^^^
SyntaxError: invalid escape sequence '\s'

[targos]

Pull request was landed without a full CI run or metadata in the commit message. I force-pushed main to cancel it. Unfortunately we cannot reopen a merged PR. @josusky can you please open a new one?

[josusky]

@targos I am a bit lost. I can certainly create a new PR with the same code change but what should be then the difference to this one?

[targos]

This one was already merged, so we cannot merge it again.

[josusky]

Fair enough, the new PR is #46649