I’m pretty sure it’s not the intent of the wording, and I would like our friendly wordsmiths to help work out how to clarify that “mapped” does in fact mean “mapped” and not “arbitrarily transformed”.

 

                   Peter

 

 

From: SG16 <sg16-bounces@lists.isocpp.org> On Behalf Of Corentin via SG16
Sent: 28 May 2020 13:50
To: C++ Core Language Working Group <core@lists.isocpp.org>
Cc: Corentin <corentin.jabot@gmail.com>; SG16 <sg16@lists.isocpp.org>
Subject: [SG16] To which extent characters can be replaced or removed in phase 1?

 

EXTERNAL MAIL

Hello, 

 

This GCC issue https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38433 argues that it is valid

for an implementation to remove trailing whitespaces as part of the implementation defined mapping described in translation phase 1. [lex.phases]

 

Is it the intent of that wording?

Should it be specified that this implementation defined mapping should preserve the semantic of each abstract character present in the physical source file?

If not, is it a valid implementation to perform arbitrary text transformation in phase 1 such as replacing "private" by "public" or replacing all "e" by a "z" ?

 

Thanks, 

 

Corentin

 

 

For reference here is the definition of abstract character in Unicode 13 

http://www.unicode.org/versions/Unicode13.0.0/ch03.pdf#G2212

 

Abstract character: A unit of information used for the organization, control, or representation of textual data.
• When representing data, the nature of that data is generally symbolic as
opposed to some other kind of data (for example, aural or visual). Examples of
such symbolic data include letters, ideographs, digits, punctuation, technical
symbols, and dingbats.
• An abstract character has no concrete form and should not be confused with a
glyph.
• An abstract character does not necessarily correspond to what a user thinks of
as a “character” and should not be confused with a grapheme.
• The abstract characters encoded by the Unicode Standard are known as Unicode abstract characters.
• Abstract characters not directly encoded by the Unicode Standard can often be
represented by the use of combining character sequences.