12.4.1.4 C and C++ Defaults

If you allow No value for GDBN to set type and range checking automatically, they both default to off whenever the working language changes to C or C++. This happens regardless of whether you or No value for GDBN selects the working language.

If you allow No value for GDBN to set the language automatically, it recognizes source files whose names end with ‘.c’, ‘.C’, or ‘.cc’, etc, and when No value for GDBN enters code compiled from one of these files, it sets the working language to C or C++. See section Having No value for GDBN Infer the Source Language, for further details.