10-compiler-internals.md

Constraint Kinds

Constraint Type	Description	Example Code Generating the Constraint
Equality(T, U)	Asserts that type T must be exactly the same as type U. The most fundamental constraint.	let x = y;
NonVoidEquality(T, U)	Asserts T must equal U, and additionally ensures the unified type is not void.	let my_variable = some_expression;
FunctionSignature(Callee, Params, Return)	Models a direct function call, asserting that Callee is a function type with Params and Return type.	my_function(10);
MethodCall(Instance, Callee, Args, Return)	Models a method call, linking the Instance type to the Callee signature and its Args/Return.	my_vector.push(5);
Operation(Result, Trait, Lhs, Rhs)	Models a trait-based operator, stating Result is the Output of Trait<Rhs> implemented for Lhs.	let result = a + b;
InstanceMemberAccess(Result, Base, Member)	Models accessing a field or method on an instance variable. Result is the type of the Member.	let x = my_struct.field;
StaticMemberAccess(Result, Base, Member)	Models accessing a static member, like an enum variant or associated function, on a Base type.	let color = Color.Red;
FullyQualifiedAccess(Result, Ty, Tr, Member)	Models a fully qualified path [Ty as Tr].Member, used to disambiguate or access associated items.	let default_val = [Vec<int> as Default].default();
Cast(Source, Target)	Asserts that a value of type Source can be legally cast to Target.	let x = 5.0 as int;
ExpressionStatement(Inner, Result)	Determines the type of a statement. Result is never if Inner diverges, otherwise void.	some_function();