Date: 2019-06-26 10:10:35 +0200
From: @swingbit
To: SQL devs <>
Version: 11.33.3 (Apr2019)
CC: @PedroTadim

Last updated: 2019-09-02 16:05:27 +0200

Comment 27086

Date: 2019-06-26 10:10:35 +0200
From: @swingbit

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36
Build Identifier:

Compiling Apr2019 tip on FC30, gcc (GCC) 9.1.1 20190503
configure : --disable-debug --disable-developer --disable-assert --enable-optimize

In file included from /usr/include/string.h:494,
from src/monetdb5/mal/../../gdk/gdk.h:316,
from src/monetdb5/mal/mal.h:17,
from src/monetdb5/mal/mal_type.h:11,
from src/monetdb5/mal/mal_instruction.h:12,
from src/monetdb5/mal/mal_exception.h:11,
from src/monetdb5/mal/mal_import.h:12,
from src/monetdb5/mal/mal_import.c:28:
In function ‘strncpy’,
inlined from ‘mal_cmdline’ at src/monetdb5/mal/mal_import.c:305:3,
inlined from ‘compileString’ at src/monetdb5/mal/mal_import.c:326:6:
/usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/monetdb5/mal/mal_import.c: In function ‘compileString’:
src/monetdb5/mal/mal_import.c:318:18: note: length computed here
318 | int len = (int) strlen(s);
| ^~~~~~~~~
In file included from /usr/include/string.h:494,
from src/monetdb5/mal/../../gdk/gdk.h:316,
from src/monetdb5/mal/mal.h:17,
from src/monetdb5/mal/mal_type.h:11,
from src/monetdb5/mal/mal_instruction.h:12,
from src/monetdb5/mal/mal_exception.h:11,
from src/monetdb5/mal/mal_import.h:12,
from src/monetdb5/mal/mal_import.c:28:
In function ‘strncpy’,
inlined from ‘mal_cmdline’ at src/monetdb5/mal/mal_import.c:305:3,
inlined from ‘callString’ at src/monetdb5/mal/mal_import.c:400:6:
/usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/monetdb5/mal/mal_import.c: In function ‘callString’:
src/monetdb5/mal/mal_import.c:394:21: note: length computed here
394 | int i, len = (int) strlen(s);
| ^~~~~~~~~
cc1: all warnings being treated as errors
make[6]: *** [Makefile:795: libmal_la-mal_import.lo] Error 1
make[6]: *** Waiting for unfinished jobs....
make[5]: *** [Makefile:493: all] Error 2
make[4]: *** [Makefile:532: all-recursive] Error 1
make[3]: *** [Makefile:486: all] Error 2
make[2]: *** [Makefile:594: all-recursive] Error 1
make[1]: *** [Makefile:524: all] Error 2
make: *** [Makefile:175: compile] Error 2

Reproducible: Always

Comment 27088

Date: 2019-06-26 15:03:02 +0200
From: MonetDB Mercurial Repository <>

Changeset c15ea2e68434 made by Pedro Ferreira pedro.ferreira@monetdbsolutions.com in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=c15ea2e68434

Changeset description:

Compilation fixes for bug #6720.

Comment 27091

Date: 2019-06-26 17:09:38 +0200
From: @swingbit

Pedro,

There is one more strncpy (which triggers the same compilation issue) at monetdb5/modules/mal/mdb.c:703

Fixing this on top of your previous commit makes it compile correctly.

Comment 27093

Date: 2019-06-26 18:10:54 +0200
From: @PedroTadim

I didn't get that error. However if I fix it in mdb.c:703, the error will be thrown elsewhere, because we use strncpy in many places.

Comment 27094

Date: 2019-06-26 18:40:41 +0200
From: @swingbit

Mh, strange. I got only an error on that one and after fixing it I got no more errors.

Are you using gcc 9?

In any case, isn't it a good idea to change all occurrences of strncp into memcpy? strncpy will keep giving compilation errors. As far as I know, the only advantage of strncpy is that it pads the destination with 0s if the string is shorter than n. But in most cases that's not needed.

Comment 27137

Date: 2019-07-15 10:44:45 +0200
From: @sjoerdmullender

Changing all strncpy calls to memcpy is not a priority. What is a priority is making sure the system compiles cleanly on as many environments as is reasonable (which includes the latest gcc).
I myself use the latest Fedora release on my laptop (which has gcc 9.1.1), but don't always compile an optimized version there (which was needed to trigger the message).