remove GCC '... may be used uninitialized' warnings

[CheyiLin]

It's a minor refactoring that reduces GCC warnings, so my users will not be scared when they are upgrading. Hope you would consider the pull request, very appreciated!

[starwing]

okay, I will look into this :)

[starwing]

I have checked the code, now it should be no any warnings in -O3 -Wall -Wextra :)

[starwing]

@CheyiLin

[CheyiLin]

I still got those warnings :sob: Maybe this issue is related to my compiler?

CentOS 6.6 x86_64, gcc version 4.4.7 20120313 (Red Hat 4.4.7-11) (GCC)

$ gcc -O3 -fPIC -Wall -Wextra -shared -o utf8.so -I$(LUADIR) lutf8lib.c

lutf8lib.c: In function 'Lutf8_widthindex':
lutf8lib.c:604: warning: 'ch' may be used uninitialized in this function
lutf8lib.c: In function 'matchbracketclass':
lutf8lib.c:747: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:755: warning: 'next' may be used uninitialized in this function
lutf8lib.c: In function 'Lutf8_codepoint':
lutf8lib.c:386: warning: 'code' may be used uninitialized in this function
lutf8lib.c: In function 'Lutf8_width':
lutf8lib.c:586: warning: 'ch' may be used uninitialized in this function
lutf8lib.c: In function 'convert':
lutf8lib.c:330: warning: 'ch' may be used uninitialized in this function
lutf8lib.c: In function 'Lutf8_escape':
lutf8lib.c:445: warning: 'ch' may be used uninitialized in this function
lutf8lib.c: In function 'Lutf8_byte':
lutf8lib.c:360: warning: 'ch' may be used uninitialized in this function
lutf8lib.c: In function 'match':
lutf8lib.c:875: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:788: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:788: note: 'ch' was declared here
lutf8lib.c:788: warning: 'begin' may be used uninitialized in this function
lutf8lib.c:788: note: 'begin' was declared here
lutf8lib.c:788: warning: 'end' may be used uninitialized in this function
lutf8lib.c:788: note: 'end' was declared here
lutf8lib.c:696: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:696: note: 'ch' was declared here
lutf8lib.c:696: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:696: note: 'ch' was declared here
lutf8lib.c:773: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:773: note: 'ch' was declared here
lutf8lib.c:773: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:773: note: 'ch' was declared here
lutf8lib.c:773: warning: 'pch' may be used uninitialized in this function
lutf8lib.c:773: note: 'pch' was declared here
lutf8lib.c:773: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:773: note: 'ch' was declared here
lutf8lib.c:773: warning: 'pch' may be used uninitialized in this function
lutf8lib.c:773: note: 'pch' was declared here
lutf8lib.c: In function 'Lutf8_gsub':
lutf8lib.c:1249: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:1166: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:1166: note: 'ch' was declared here
lutf8lib.c: In function 'Lutf8_next':
lutf8lib.c:510: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:510: note: 'ch' was declared here
lutf8lib.c: In function 'Lutf8_charpos':
lutf8lib.c:510: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:510: note: 'ch' was declared here
lutf8lib.c:510: warning: 'ch' may be used uninitialized in this function
lutf8lib.c:510: note: 'ch' was declared here

[starwing]

you use gcc 4.4? that may be too old, I only have gcc 4.8.2 and 4.9.2, all don't have warnings.

[CheyiLin]

Unfortunately in CentOS 6, the default gcc compiler is still 4.4.7. :disappointed: I can install newer gcc packages from unofficial sources (means neither CentOS nor RedHat) but it increase the config complexity and dependencies, which is what I want to avoid.

Could you please consider mergeing this PR again? If yes I would commit the patch later, thanks.

[starwing]

Maybe you can build this library with -w to Inhibit warnings? I mean, not adding these initialize value is good if we really forget to initialize a variable, so add these initialize is not so good.

Or, if you really want it don't have warnings at gcc 4.4, I will try that (I can download a MinGW version and fix it), but I need do it at weekend :(

[CheyiLin]

Or, if you really want it don't have warnings at gcc 4.4, I will try that

That would be great! Please do this when you have some extra time. :smiley: Very appreciated!

[starwing]

I have a CentOS 6.5 server today, and it have gcc 4.4.7, so I tried compile luautf8, but I doesn't seem any warnings :(

this is the log:

sw@10-6-23-155: ~/prebuilt/luautf8 master!
 $ gcc -shared -fPIC -Wall lutf8lib.c -o lua-utf8.so                 [12:58:07]

sw@10-6-23-155: ~/prebuilt/luautf8 master!
 $ gcc -v                                                            [12:58:17]
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.4.7 20120313 (Red Hat 4.4.7-4) (GCC)

[CheyiLin]

Sorry, I conformed that the warnings are exactly caused by gcc 4.4 optimization flag -O3.

[starwing]

Okay, I have found the bug cause the warnings, you can try the git HEAD. Thank you very much for reporting :)

[CheyiLin]

Tested and no warning!! I never thought that would be a bug before. :sweat_smile: Thanks.