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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: "A diagram of C23 basic types"
Date: Fri, 04 Apr 2025 12:18:58 -0700
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David Brown <david.brown@hesbynett.no> writes:
[...]
> It is easy to write code that is valid C23, using a new feature copied
> from C++, but which is not valid C++ :
>
> 	constexpr size_t N = sizeof(int);
> 	int * p = malloc(N);

It's much easier than that.

    int class;

Every C compiler will accept that.  Every C++ compiler will reject
it.  (I think the standard only requires a diagnostic, which can
be non-fatal, but I'd be surprised to see a C or C++ compiler that
generates an object file after encountering a syntax error).

Muttley seems to think that because, for example, "gcc -c foo.c"
will compile C code and "gcc -c foo.cpp" will compile C++ code,
the C and C++ compilers are the same compiler.  In fact they're
distinct frontends with shared backend code, invoked differently
based on the source file suffix.  (And "g++" is recommended for C++
code, but let's not get into that.)

For the same compiler to compile both C and C++, assuming you don't
unreasonably stretch the meaning of "same compiler", you'd have to
have a parser that conditionally recognizes "class" as a keyword or
as an identifier, among a huge number of other differences between
the two grammars.  As far as I know, nobody does that.

You and I know he's wrong.  Arguing with him is a waste of everyone's
time.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */