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[Tinycc-devel] Possible bug in _Generic code, need help to get it fixed
From: |
K K |
Subject: |
[Tinycc-devel] Possible bug in _Generic code, need help to get it fixed |
Date: |
Fri, 21 Feb 2020 07:13:49 +0000 |
Hello all,
I got the error message "type match twice" using the following code (built tcc
from HEAD, running on Windows 10 64 bit):
#include <stdio.h>
void main() {
const double d = 0;
printf(_Generic((d), double: "%g", long double: "%Lg", default:
"<unknown>"), d);
}
The same problem was already mentioned
https://lists.gnu.org/archive/html/tinycc-devel/2019-08/msg00012.html.
I'm not perfectly in knowing the tcc sources, but in my opinion I discovered
the source of this problem at line
https://repo.or.cz/tinycc.git/blob/HEAD:/tccgen.c#l4591 and the following line,
which changes a correctly parsed type "long double" back to "double" and so
leads at line https://repo.or.cz/tinycc.git/blob/HEAD:/tccgen.c#l5433 and some
following lines to the incorrect assumption, that the _Generic definition
contains two controlling expressions of the same type. This change was done
back in 2017 by grischka during a long review
https://repo.or.cz/tinycc.git/commit/1443039416dd02750765efde1af35e31c8d41be3.
I cannot determine if https://repo.or.cz/tinycc.git/blob/HEAD:/tccgen.c#l4592
is wrong because I do not know the intension why it was added. And I do not
know why this type change is done only for PE targets, too. So maybe grischka
or someone with more knowledge about the tcc sources is able to check this
again or someone can point me in further directions.
Thanks in advance,
Kernel
- [Tinycc-devel] Possible bug in _Generic code, need help to get it fixed,
K K <=