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d_demangle_callback may use dc uninitialized, at least says gcc 4.3.2 Debian/powerpc
- From: Jay K <jay dot krell at cornell dot edu>
- To: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 9 Jun 2010 16:07:13 +0000
- Subject: d_demangle_callback may use dc uninitialized, at least says gcc 4.3.2 Debian/powerpc
/home/jay/src/gcc-4.5.0/libiberty/cp-demangle.c: In function ‘d_demangle_callback’:
/home/jay/src/gcc-4.5.0/libiberty/cp-demangle.c:4767: warning: ‘dc’ may be used uninitialized in this function
jay@plin:~/obj/gcc45$ gcc -v
Using built-in specs.
Target: powerpc-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.2-1.1' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --disable-softfloat --enable-secureplt --enable-targets=powerpc-linux,powerpc64-linux --with-cpu=default32 --with-long-double-128 --enable-checking=release --build=powerpc-linux-gnu --host=powerpc-linux-gnu --target=powerpc-linux-gnu
Thread model: posix
gcc version 4.3.2 (Debian 4.3.2-1.1)
jay@plin:~/obj/gcc45$ uname -a
Linux plin 2.6.26-2-powerpc #1 Thu Feb 11 01:36:51 UTC 2010 ppc GNU/Linux
The warning appears to be false:
? enum
??? {
????? DCT_TYPE,
????? DCT_MANGLED,
????? DCT_GLOBAL_CTORS,
????? DCT_GLOBAL_DTORS
??? }
? type;
? struct demangle_component *dc;
...
? if ...
??? type = DCT_MANGLED;
? else if ...
??? type = ... ? DCT_GLOBAL_CTORS : DCT_GLOBAL_DTORS;
? else ...
????? type = DCT_TYPE;
...
??? switch (type)
????? {
????? case DCT_TYPE:
??? dc = ...
??? break;
????? case DCT_MANGLED:
??? dc = ...
??? break;
????? case DCT_GLOBAL_CTORS:
????? case DCT_GLOBAL_DTORS:
??? ...
??? dc = ...
??? break;
????? }
?????
Nevertheless:
jbook2:~ jay$ diff -u /Users/jay/src/orig/gcc-4.5.0/libiberty/cp-demangle.c /Users/jay/src/gcc-4.5.0/libiberty/cp-demangle.c
--- /Users/jay/src/orig/gcc-4.5.0/libiberty/cp-demangle.c??? 2010-03-22 13:38:35.000000000 -0700
+++ /Users/jay/src/gcc-4.5.0/libiberty/cp-demangle.c??? 2010-06-09 09:00:09.000000000 -0700
@@ -4764,7 +4764,7 @@
???? }
?? type;
?? struct d_info di;
-? struct demangle_component *dc;
+? struct demangle_component *dc = { 0 };
?? int status;
?
?? if (mangled[0] == '_' && mangled[1] == 'Z')
Appears same in gcc trunk.
Optimization at least with better/newer compiler should remove the initialization but I didn't check.
?- Jay