[SOLVED] What are the useful GCC flags for C?

Issue

Beyond setting -Wall, and setting href="https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html#index-std-1" rel="nofollow noreferrer">-std=XXX, what other really useful, but less known compiler flags are there for use in C?

I'm particularly interested in any additional warnings, and/or and turning warnings into errors in some cases to absolutely minimize any accidental type mismatches.

Solution

Several of the -f code generation options are interesting:

• -fverbose-asm is useful if you're compiling with -S to examine the assembly output - it adds some informative comments.

• -finstrument-functions adds code to call user-supplied profiling functions at every function entry and exit point.

• --coverage instruments the branches and calls in the program and creates a coverage notes file, so that when the program is run coverage data is produced that can be formatted by the gcov program to help analysing test coverage.

• -fsanitize={address,thread,undefined} enables the AddressSanitizer, ThreadSanitizer and UndefinedBehaviorSanitizer code sanitizers respectively. These instrument the program to check for various sorts of errors at runtime.

Previously this answer also mentioned -ftrapv, however this functionality has been superseded by -fsanitize=signed-integer-overflow which is one of the sanitizers enabled by -fsanitize=undefined.

Answered By - caf

Answer Checked By - David Marino (WPSolving Volunteer)