Hi, I have few questions about inbuilt mechanism of gcc/g++ for warning about uninitialized variable.
I am interested in cases where compiler is unable to warn. I am aware that all the known bugs about warning-failure are mentioned at bugzilla http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639 a) The compiler activates the warning mechanism only if optimisation is enabled at compilation time with -O option. For all the bugs that I went through at bugzilla, the failure is not -O level dependent. The warning-failure occurs for all levels of optimisation. So, I believe this is the general case. But then I came across the following failure case. //////////////////// #include <stdio.h> int Check(int *a) { if (*a == 0) { printf("This is sample \n"); } return *a; } int main() { int call; Check(&call); return 0; } ///////////////////// This one fails to warn when compiled with any level below 3. With -O3, gcc is able to warn. Can someone tell me which is the corresponding bug logged at bugzilla ? Are there any more such bugs which disappear when compiled with specific -O level ? b) Are there any known "fail to do uninitialised-warning" gcc bugs which are language-dependent ? I mean bugs which occur only in C++ , but not in C. ( Bugs which arise out of C++ language features/syntax. ) . If so, I would like to know. Elsewhere, someone pointed out to me that these are not "bugs", but occur due to tradeoff in compiler against false positive warnings. I am referring them as "bugs" only because compiler hackers do so. thanks for your time Uma shankar
