Casting and low-level memory representation

!!! warning This auditors' handbook is frozen and obsolete; the Nim language manual alongside other Nim documentation, Status Nim style guide, Chronos guides, and Nim by Example supercede it.

Conversions

Casting to a signed integer will lead to a range check. Conversion to an unsigned integer even from a negative signed integer will NOT lead to a range check (https://github.com/nim-lang/RFCs/issues/175) https://nim-lang.org/docs/manual.html#statements-and-expressions-type-conversions

Casting integers

Unsigned integer casts behave like C.

Upcasting will lead to zero extension Downcasting will lead to truncation

Signed integer ranges will not be checked with a cast.

Casting to/from other types

Casting to or from any other types will be done through:

• union casts by default
• or C conversion if the type is a pointer.

In practice this means that the bit-pattern will be reinterpreted as the new type, similar to C++ reinterpret cast.