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Subject: Re: [PATCH] BaseTools: Fix python3.8 SyntaxWarning
To: Cole Robinson <crobinso@redhat.com>, devel@edk2.groups.io
References: <6692fad1d6b57307a5da195986ed23074021fc88.1562952568.git.crobinso@redhat.com>
Cc: Bob Feng <bob.c.feng@intel.com>, Liming Gao <liming.gao@intel.com>
From: "Laszlo Ersek" <lersek@redhat.com>
Message-ID: <1425e3e8-a476-49c1-7692-61445caf7c3c@redhat.com>
Date: Fri, 12 Jul 2019 23:03:22 +0200
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On 07/12/19 19:29, Cole Robinson wrote:
> Building with python3.8 shows a warning like:
> 
> SyntaxWarning: invalid escape sequence \(
>   GuidName = re.compile("\(GUID=[-a-fA-F0-9]+")
> 
> It seems harmless, but it's easy enough to fix: mark the string as
> raw with the 'r' prefix like is used elsewhere in the file

I think the intent is to escape the opening paren '(' so that it lose
its special regex meaning. Is that correct?

And, the issue is that the backslash, meant for escaping the paren, in
effect introduces a *string literal* escape sequence. Is that correct?

If so, would it be correct to replace '\(' with '\\('?

(IOW, use the string literal escape sequence \\ to encode a raw \, and
then let the raw \ escape the ( on the regex level.)

Anyway, after reading up a bit on raw string literals, the patch appears
to do the same, only more readably. :)

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

(CC'ing BaseTools maintainers Bob and Liming.)

Thanks!
Laszlo

> 
> Signed-off-by: Cole Robinson <crobinso@redhat.com>
> ---
>  BaseTools/Source/Python/build/build.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/BaseTools/Source/Python/build/build.py b/BaseTools/Source/Python/build/build.py
> index 8c3315619a..d6006b651f 100644
> --- a/BaseTools/Source/Python/build/build.py
> +++ b/BaseTools/Source/Python/build/build.py
> @@ -1499,7 +1499,7 @@ class Build():
>          if self.Fdf:
>              # First get the XIP base address for FV map file.
>              GuidPattern = re.compile("[-a-fA-F0-9]+")
> -            GuidName = re.compile("\(GUID=[-a-fA-F0-9]+")
> +            GuidName = re.compile(r"\(GUID=[-a-fA-F0-9]+")
>              for FvName in Wa.FdfProfile.FvDict:
>                  FvMapBuffer = os.path.join(Wa.FvDir, FvName + '.Fv.map')
>                  if not os.path.exists(FvMapBuffer):
>