+++ title = "My Favorite g++ Flags for a New Project" date = 2022-03-02T00:00:00 lastmod = 2022-03-02T00:00:00 draft = false

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authors = ["Carl Pearson"]

tags = ["C++"]

summary = "C++ is hard; make it a bit easier."

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+++

The summaries are taken from https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

• -Wall: turns on many warnings, but not "all."
• -Wextra: turns on even more warnings, but still not all.
• -Wcast-align: warn whenever a pointer is cast such that the required alignment is increased (char* -> int*).
• -Wcast-qual: warn when qualifier (cosnst) is cast away, or introduces a qualifier in an unsafe way.
• -Wdisabled-optimization: warn if a requested optimization pass is disable.
• -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)

Honorable Mentions

• -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"