On 14/05/2023 07:38, Po Lu via Gcc wrote:
No, all you have to do is to tell GNU CC to compile Standard C. But
what's being debated here is the behavior of GNU CC when translating
both Standard C and GNU C, so your demonstration is almost completely
pointless.
You keep using the term "Standard C", but you are using it incorrectly.
"Standard C" means "The language C as recognised by standardisation
bodies". It is, currently, ISO/IEC 9899:2018 - also known as C17/C18.
(The standard was completed in C17, but not actually published until C18.)
If you want to refer to older standards (or unpublished future
standards), you should do so explicitly - C90, C99, C11, C23.
Then there are "extended standards" - specific documented extensions on
top of an official standard. "gnu17" would be an example of that.
Any language from before the first ANSI C is /not/ standard, since it is
not based on any standards document. The nearest would be the de-facto
"standard" (anything "de-facto" is, by definition, not an actual
standard) language described in the first edition of "The C Programming
Language", and known as "K&R C". Many of the C compilers of that time
followed the book and implemented - modulo bugs, extensions,
inconsistencies, and missing features - the language "K&R C". Many also
had their own variants, as "C" was already popular before the book was
published.
So - if you are referring to "K&R C", then use that term. It is quite
well defined, and accurately describes a popular pre-standard C language.
And you may note that if you look at the GCC manual, it supports all
standards of C (at least as closely as possible). All /standards/.
"K&R C" is not a standard, and not officially supported by GCC - there
has never, to my knowledge, been any kind of guarantee that GCC would
support pre-standard syntax. There has only been a guarantee that
appropriate choices of flags would cause pre-standard syntax to be
detected and rejected or diagnosed. Ironically, the discussion here,
with its suggestions of explicit flags to allow "K&R C" constructs, has
come closer to guaranteeing support for that pre-standard dialect than
GCC has ever had before.
<https://gcc.gnu.org/onlinedocs/gcc/Standards.html>
<https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html>
(When people refer to "ANSI C", they almost invariably mean the ANSI
standard from 1989 that formed, after a bit of section renumbering, ISO
C90, it is worth remembering that ANSI actually delegates the C
standardisation to ISO. So "ANSI C" refers to the same language as
C17/C18.)
