15.4.1.5 C and C++ Type and Range Checks

By default, when gdb parses C or C++ expressions, type checking is not used. However, if you turn type checking on, gdb considers two variables type equivalent if:

• The two variables are structured and have the same structure, union, or enumerated tag.
• The two variables have the same type name, or types that have been declared equivalent through typedef.

Range checking, if turned on, is done on mathematical operations. Array indices are not checked, since they are often used to index a pointer that is not itself an array.