Struct FlowFacts 

pub struct FlowFacts {
    pub type_narrowings: FxHashMap<String, TypeId>,
    pub definite_assignments: FxHashSet<String>,
    pub tdz_violations: FxHashSet<String>,
}

Flow facts that represent the state of variables at a specific program point.

This structure bridges the checker’s flow analysis and the solver’s type system by tracking what we know about variables at a given control flow point.

Fields

type_narrowings: FxHashMap<String, TypeId>

Type narrowings: maps variable name to its narrowed type

definite_assignments: FxHashSet<String>

Variables that are definitely assigned at this point

tdz_violations: FxHashSet<String>

Variables that violate TDZ (used before declaration)

Implementations

impl FlowFacts

pub fn new() -> Self

Create empty flow facts

pub fn add_narrowing(&mut self, variable: String, narrowed_type: TypeId)

Add a type narrowing for a variable

pub fn mark_definitely_assigned(&mut self, variable: String)

Mark a variable as definitely assigned

pub fn mark_tdz_violation(&mut self, variable: String)

Mark a variable as having a TDZ violation

pub fn is_definitely_assigned(&self, variable: &str) -> bool

Check if a variable is definitely assigned

pub fn has_tdz_violation(&self, variable: &str) -> bool

Check if a variable has a TDZ violation

pub fn get_narrowed_type(&self, variable: &str) -> Option<TypeId>

Get the narrowed type for a variable (if any)

pub fn merge(&self, other: &Self) -> Self

Merge two flow fact sets (for join points in control flow)

At control flow join points (e.g., after if/else), we:

• Keep only narrowings that are present in both branches (intersection)
• Keep only definite assignments that are present in both branches
• Keep only TDZ violations that are present in both branches (intersection)

Trait Implementations

impl Clone for FlowFacts

fn clone(&self) -> FlowFacts

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FlowFacts

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FlowFacts

fn default() -> FlowFacts

Returns the “default value” for a type.