stringify MAKE_SQLSTATE()
Hi!
Following discussion at https://commitfest.postgresql.org/5/190/ patch, I found
(at seems to me) a way to stringify MAKE_SQLSTATE(), the idea is to use char
array as string:
#include <stdio.h>
#define MAKE_SQLSTATE(ch1,ch2,ch3,ch4,ch5) \
((char[]){(char)(ch1),(char)(ch2),(char)(ch3),(char)(ch4),(char)(ch5),(char)'\0'})
#define ERRCODE_WARNING_DEPRECATED_FEATURE MAKE_SQLSTATE('0','1','P','0','1')
int
main(int argn, char* argv[])
{
char *x = ERRCODE_WARNING_DEPRECATED_FEATURE;
printf("%s\n", x);
return 0;
}
That works for clang ang gcc48 with flags -Wall -Wextra -ansi (or -std=c90)
without warnings, but doesn't work with -pedantic. Is that enough to to work
with other compilers?
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Teodor Sigaev E-mail: teodor@sigaev.ru
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Teodor Sigaev <teodor@sigaev.ru> writes:
Following discussion at https://commitfest.postgresql.org/5/190/ patch, I found
(at seems to me) a way to stringify MAKE_SQLSTATE(), the idea is to use char
array as string:
#define MAKE_SQLSTATE(ch1,ch2,ch3,ch4,ch5) \
((char[]){(char)(ch1),(char)(ch2),(char)(ch3),(char)(ch4),(char)(ch5),(char)'\0'})
I'm pretty sure that's a gcc-ism, not standard C.
As I mentioned in the other thread, if we wanted to provide string
versions of the ERRCODE macros, the safest way to do it would be
to create a separate header file with defines like
#define ERRCODE_WARNING_DEPRECATED_FEATURE "01P01"
Now that we generate errcodes.h from errcodes.txt anyway, it would
certainly be a trivial extension of the build infrastructure to make
a second header like this.
The real question is do we want to. What's your use-case for this?
regards, tom lane
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#define MAKE_SQLSTATE(ch1,ch2,ch3,ch4,ch5) \
((char[]){(char)(ch1),(char)(ch2),(char)(ch3),(char)(ch4),(char)(ch5),(char)'\0'})I'm pretty sure that's a gcc-ism, not standard C.
Hmm, after some digging: the feature is called compound literals and it was
introduced in c99 although gcc has support in c90. To disable this support it's
needed a flag -pedantic. Sorry.
The real question is do we want to. What's your use-case for this?
Just do not have a hardcoded values. It is too easy to make a mistake in
hardcoded value.
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Teodor Sigaev E-mail: teodor@sigaev.ru
WWW: http://www.sigaev.ru/
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