When using variable parameters indirectly (the variable-parameter function
calls another function to format its parameters giving it the original address
of the format string), the results are usually ok for non-optimized builds and
cause segmentation faults in optimized builds.
In a large project I also detected that unoptimized builds would cause
segmentation faults if the variable-parameter function declared a char buffer,
and would not fail if it declared an int buffer of the same total size. However
this is difficult to reproduce, so the test case I send you does not show this.
In the code I send you you can see "main" calling "format_direct" to format
some variable parameters, which in turn calls "format_indirect" to do the
actual work. This is a pattern I use a lot and for which I never had a problem
under Windows with any of Microsoft's Visual Studio versions (I'm fairly new to
LINUX, this is my first software port project).
If this test case is compiled with "g++ -v -save-temps
gcc_bug_format_indirect.cpp -o gcc_bug_format_indirect.exe.ok" then it works
ok, but if it is compiled with "g++ -v -save-temps -O2
gcc_bug_format_indirect.cpp -o gcc_bug_format_indirect.exe.ko" it causes a
segmentation fault (at least on my system it does, when it doesn't cause a
segmentation fault the results are just wrong).
I attach the preprocessed file, the source file, and the compilation script I
used.
--
Summary: Indirect variable parameters sometimes cause
segmentation fault
Product: gcc
Version: 4.3.3
Status: UNCONFIRMED
Severity: blocker
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rogerio at rilhas dot com
GCC build triplet: i686-virtualboxvm-ubuntu?
GCC host triplet: i686-virtualboxvm-ubuntu?
GCC target triplet: i686-virtualboxvm-ubuntu?
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45249
