Debugging critical warnings from GLib code

tl;dr: G_DEBUG=fatal-warnings gdb ./my-program

If you have some code which uses GLib, and it emits a critical warning, for example if a g_return_if_fail() check fails or if a g_warning() message is emitted, how do you track it down and debug it?

Run your code under gdb with G_DEBUG=fatal-warnings (for g_return_if_fail() and g_warning()) or G_DEBUG=fatal-criticals (for g_return_if_fail()), and gdb will break execution when the failing precondition or warning is reached. If there are multiple warnings and you want to skip through to get to a particular one, just use the continue command in gdb until you reach the one you want.

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