Some languages, such as Modula-2, are strongly typed, meaning that the arguments to operators and functions have to be of the correct type, otherwise an error occurs. These checks prevent type mismatch errors from ever causing any run-time problems. For example,
1 + 2 => 3 but error--> 1 + 2.3
The second example fails because the
CARDINAL 1 is not
type-compatible with the
For the expressions you use in GDB commands, you can tell the GDB type checker to skip checking; to treat any mismatches as errors and abandon the expression; or to only issue warnings when type mismatches occur, but evaluate the expression anyway. When you choose the last of these, GDB evaluates expressions like the second example above, but also issues a warning.
Even if you turn type checking off, there may be other reasons
related to type that prevent GDB from evaluating an expression.
For instance, GDB does not know how to add an
struct foo. These particular type errors have nothing to do
with the language in use, and usually arise from expressions, such as
the one described above, which make little sense to evaluate anyway.
Each language defines to what degree it is strict about type. For instance, both Modula-2 and C require the arguments to arithmetical operators to be numbers. In C, enumerated types and pointers can be represented as numbers, so that they are valid arguments to mathematical operators. See section Supported languages, for further details on specific languages.
GDB provides some additional commands for controlling the type checker:
set check type auto
set check type on
set check type off
set check type warn
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