Caution
You’re reading a draft of the Ferrocene Language Specification. Some parts of this document might be missing, incomplete or incorrect. Our aim is to have the specification ready by the end of 2022.
16. Exceptions and Errors¶
Legality Rules
16:1 The Rust programming language lacks exceptions and exception handlers. Instead, the language uses the following tiered error handling scheme:
16:2 A possibly absent value is represented usually using enum
core::option::Option.16:3 The result of a possibly erroneous computation is represented usually using enum
core::result::Result.16:4 Erroneous behavior is signaled using macro
core::panic.
16:5
Enum core::option::Option indicates whether a value is
either present using core::option::Option::Some or absent using
core::option::Option::None.
16:6
Enum core::result::Result indicates whether a computation completed
successfully and produced a value using core::result::Result::Ok or
the computation failed with an error using core::result::Result::Err.
16.1. Panic¶
Legality Rules
16.1:1
A panic is an abnormal program state caused by invoking macro
core::panic.
Dynamic Semantics
16.1:2
Invoking macro core::panic has the following runtime effects:
16.1:3 Control flow halts the execution of the current thread.
16.1:4 Control flow of the current thread resumes execution by invoking the function subject to attribute
panic_handler.
Undefined Behavior
16.1:5 It is undefined behavior when a panic crosses a foreign function interface boundary.
Examples
panic!("This was a terrible mistake!");
16.2. Abort¶
Legality Rules
16.2:1 Abort is the immediate termination of a program.
Dynamic Semantics
16.2:2 Abort has the following runtime effects:
16.2:3 Control flow halts the execution of all threads.
16.2:4 The program terminates.