bindVariableTo() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/TypeInference/InferTypes.ts lines 644–698

  bindVariableTo(v: TypeVar, type: Type): void {
    if (type.kind === 'Poly') {
      //  Ignore PolyType, since we don't support polymorphic types correctly.
      return;
    }

    if (this.substitutions.has(v.id)) {
      this.unify(this.substitutions.get(v.id)!, type);
      return;
    }

    if (type.kind === 'Type' && this.substitutions.has(type.id)) {
      this.unify(v, this.substitutions.get(type.id)!);
      return;
    }

    if (type.kind === 'Phi') {
      CompilerError.invariant(type.operands.length > 0, {
        reason: 'there should be at least one operand',
        loc: GeneratedSource,
      });

      let candidateType: Type | null = null;
      for (const operand of type.operands) {
        const resolved = this.get(operand);
        if (candidateType === null) {
          candidateType = resolved;
        } else if (!typeEquals(resolved, candidateType)) {
          const unionType = tryUnionTypes(resolved, candidateType);
          if (unionType === null) {
            candidateType = null;
            break;
          } else {
            candidateType = unionType;
          }
        } // else same type, continue
      }

      if (candidateType !== null) {
        this.unify(v, candidateType);
        return;
      }
    }

    if (this.occursCheck(v, type)) {
      const resolvedType = this.tryResolveType(v, type);
      if (resolvedType !== null) {
        this.substitutions.set(v.id, resolvedType);
        return;
      }
      throw new Error('cycle detected');
    }

    this.substitutions.set(v.id, type);
  }