C++ is hard; make it a little bit easier. The summaries are taken from https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html.
The effectiveness of some of these options depends on various optmization passes. You may also be able to selectively disable warnings for certain chunks of code (https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html). This can be especially useful for header files with contents you can't control very well.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wuninitialized"
foo(b); /* no diagnostic for this one */
#pragma GCC diagnostic pop
-Wall: turns on many warnings, but not "all."-Wextra: turns on even more warnings, but still not all.-Wpedantic: Issue all the warnings demanded by strict ISO C++.-Wcast-align: warn whenever a pointer is cast such that the required alignment is increased (char* -> int*).-Wcast-qual: warn when qualifier (const) is cast away, or introduces a qualifier in an unsafe way.-Wdisabled-optimization: warn if a requested optimization pass is disabled (e.g. code is too large, has some other feature that makes g++ give up).-Wduplicated-branches: warn if if-else branches have identical bodies.-Wduplicated-cond: warn about duplicated conditions in an if-else-if chain.-Wformat=2: same as -Wformat -Wformat-nonliteral -Wformat-security -Wformat-y2k. make sure printf-style function arguments match their format strings.-Wlogical-op: warn about suspicious use of logical operators, i.e. contexts where bitwise is more likely.-Wmissing-include-dirs: warn if a user-supplied include dir does not exist.-Wnull-dereference: warn if paths that dereference a null pointer are detected.-Woverloaded-virtual: warn when a function declaration hides virtual functions from a base class-Wpointer-arith: warn about sizeof for function types or void.-Wshadow: warn about variable shadowing and global function shadowing.-Wswitch-enum: warn when a switch on an enum type is missing one of the enums.-Wvla: warn about using variable-length arrays.Also, in debug mode:
-fasynchronous-unwind-tables: allows stack unwinding from asycnrhonous events (https://gcc.gnu.org/onlinedocs/gcc/Code-Gen-Options.html)-fno-omit-frame-pointer: g++ only turns on -fomit-frame-pointer on machines where it does not interfere with debugging, so no need for this one.-Wuseless-cast: Warns when casting to the same type. Unfortunately, doesn't work well with MPI, since MPI_COMM_WORLD may be an int and casting it to MPI_Comm is a "useless cast"-Wsuggest-attribute=[pure|const|noreturn|format|cold|malloc]: I haven't spent much time with this one, it may be useful.