Module moore_svlog::typeck

Type checking and computation.

This module performs type computation and type checking of a SystemVerilog design. A large portion is dedicated to expression typing, which is the most involved angle. However, there are also other bits and pieces that compute types for things like ports or instances. Finally, there are functions that map AST nodes of type kind to actual UnpackedTypes.

Expression type checking occurs in the following sequence, and through the following queries:

1. self_determined_type evaluates an expression to its self-determined type, or returns None if the expression requires context information to determine a type. There is also need_self_determined_type which issues a diagnostic in the latter case.
2. operation_type determines if an expression has an internal type under which its operation takes place. E.g. comparisons have the expanded arg. types as operation type. There is also need_operation_type.
3. type_context determines what type the parent of an expression imposes on the expression. In an assignment for example, this would be the left hand side’s type impose on the right hand side, and vice versa. This is the main driver for casting operations, and the rest of the compiler expects the type context to fully line up with the parent’s needs.
4. type_of_expr computes the type of an expression before casting.
5. cast_type computes the final type of an expression, ensuring that its type as returned by type_of_expr is castable, and deriving a cast sequenceto thetype_context`.

Structs

CastType

A type resulting from a sequence of casts.

Enums

CastOp

A cast operation.

TypeContext

A type context imposed by a node’s surroundings.