Re: GCC accepts dynamically-sized array in sizeof with -std=c89

[Jim Wilson <wilson@tuliptree.org>]

Igor Bukanov wrote:
> With GCC 4.3.0 it compiles without a warning even with -pedantic
> -std=c89 even if the program uses dynamic array feature from C99:

It works for me.

localhost$ ./xgcc -B./ -std=c89 tmp2.c
localhost$ ./xgcc -B./ -std=c89 -pedantic tmp2.c
tmp2.c: In function ‘f’:
tmp2.c:5: warning: ISO C90 forbids variable length array
localhost$ ./xgcc -B./ -v
Reading specs from ./specs
Target: i686-pc-linux-gnu
Configured with: ../gcc/configure --enable-languages=c
Thread model: posix
gcc version 4.3.1 20080411 (prerelease) [gcc-4_3-branch revision 134209] 
(GCC)

Adding -pedantic does generate the warning.  Perhaps you expected a 
warning without -pedantic?  If you read the docs carefully, you will see 
that -std=c89 enables all features of that standard, but does not 
disable GNU extensions to that standard.  You need -pedantic for that.

Jim