Re: 7.5 beta version]

Point 1 I completely agree on: byte order, alignment, padding, etc.
is different for each platform and data cannot directly be exchanged.

Point 2: who really needs C++ ??




-------- Ursprüngliche Nachricht --------
Betreff: Re: [HACKERS] 7.5 beta version
Datum: Mon, 12 Apr 2004 11:55:45 -0700
Von: "Dann Corbit" <DCorbit@connx.com>
An: "Jeroen T. Vermeulen" <jtv@xs4all.nl>,    "Bruce Momjian"
<pgman@candle.pha.pa.us>
CC: <pgsql-hackers@postgresql.org>

> -----Original Message-----
> From: Jeroen T. Vermeulen [mailto:jtv@xs4all.nl]
> Sent: Sunday, April 11, 2004 7:28 AM
> To: Bruce Momjian
> Cc: Dann Corbit; pgsql-hackers@postgresql.org
> Subject: Re: [HACKERS] 7.5 beta version
>
>
> On Mon, Apr 05, 2004 at 09:38:13PM -0400, Bruce Momjian wrote:
> >
> > I don't think you can mix libs/binaries from different compilers.
>
> As long as it's plain old C, and the compilers adhere to the
> platform's ABI standards, why not?  Even if you compile the C
> code using a C++ compiler, as in this case, any C structs
> will be PODs and so should be compiled according to the C
> layout rules.

1.
The C language does not define alignment of structs.

The C language does not specify that an integer shall be the same size
on two different platforms.

The C language does not specify a portable way even to read and write
structs to disk and preserve alignment across platforms.

The C language does not specify that IEEE arithmetic must be used or
even that a double shall be able to represent a value larger than a
float.

2.
It is a mistake to use a C++ compiler to compile C code, because the
languages are different.  Stroustrup's statement that good C code tends
to be valid C++ code is not correct.

Mingw GCC is both a C and a C++ compiler.  Fortunately, the C compiler
is used, because there is no way that the code base would compile as C
code.  A trivial example to show why not is the frequent use of the C++
keyword 'new' in the code base.  Here is an example:
regc_color.c (225):  struct colordesc *new;
regc_color.c (251):  new = (struct colordesc *) MALLOC(n *
regc_color.c (253):  if (new != NULL)
regc_color.c (254):  memcpy(VS(new), VS(cm->cdspace), cm->ncds *
regc_color.c (258):  new = (struct colordesc *) REALLOC(cm->cd,
regc_color.c (260):  if (new == NULL)
regc_color.c (265):  cm->cd = new;

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