facts = append(facts, analysis.PackageFact{Package: k.pkg, Fact: v})
		}
	}
	s.mu.Unlock()
	return facts
}

// gobFact is the Gob declaration of a serialized fact.
type gobFact struct {
	PkgPath string          // path of package
	Object  objectpath.Path // optional path of object relative to package itself
	Fact    analysis.Fact   // type and value of user-defined Fact
}

//
// Each pass (a, p) starts with the set of facts produced by the
// same analyzer a applied to the packages directly imported by p.
// The analysis may add facts to the set, and they may be exported in turn.
// An analysis's Run function may retrieve facts by calling
// Pass.Import{Object,Package}Fact and update them using
// Pass.Export{Object,Package}Fact.
//
// A fact is logically private to its Analysis. To pass values

				ImportObjectFact:  facts.ImportObjectFact,
				ExportObjectFact:  facts.ExportObjectFact,
				AllObjectFacts:    func() []analysis.ObjectFact { return facts.AllObjectFacts(factFilter) },
				ImportPackageFact: facts.ImportPackageFact,
				ExportPackageFact: facts.ExportPackageFact,
				AllPackageFacts:   func() []analysis.PackageFact { return facts.AllPackageFacts(factFilter) },
			}

shared data structures referenced by multiple facts is preserved.

The Pass type has functions to import and export facts,
associated either with an object or with a package:

	type Pass struct {
		...
		ExportObjectFact func(types.Object, Fact)
		ImportObjectFact func(types.Object, Fact) bool

		ExportPackageFact func(fact Fact)
		ImportPackageFact func(*types.Package, Fact) bool
	}

				}
			}

			match = true
			if dest.Weight > 0 {
				fact := fmt.Sprintf("Route to host \"%s\"", dest.Destination.Host)
				if dest.Destination.Subset != "" {
					fact = fmt.Sprintf("%s subset \"%s\"", fact, dest.Destination.Subset)
				}
				fact = fmt.Sprintf("%s with weight %d%%", fact, dest.Weight)
				facts = append(facts, fact)
			}

			r = reverseBits[r]
		}

		p := pair{v, w, d}
		oldR, ok := ft.facts[p]
		if !ok {
			if v == w {
				oldR = eq
			} else {
				oldR = lt | eq | gt
			}
		}
		// No changes compared to information already in facts table.
		if oldR == r {
			return
		}
		ft.stack = append(ft.stack, fact{p, oldR})
		ft.facts[p] = oldR & r
		// If this relation is not satisfiable, mark it and exit right away

	// Cycles in the static call graph are broken
	// arbitrarily but deterministically.
	// We create noReturn facts as discovered.
	for _, fn := range decls {
		c.buildDecl(fn, funcDecls[fn])
	}

	// Build CFGs for literal functions.
	// These aren't relevant to facts (since they aren't named)
	// but are required for the CFGs.FuncLit API.
	for _, lit := range lits {
		li := funcLits[lit]

	}

	var facts []string
	for id, obj := range defs {
		if obj != nil {
			fact := fmt.Sprintf("L%d defs %s", fset.Position(id.Pos()).Line, obj)
			facts = append(facts, fact)
		}
	}
	for id, obj := range uses {
		fact := fmt.Sprintf("L%d uses %s", fset.Position(id.Pos()).Line, obj)
		facts = append(facts, fact)
	}
	slices.Sort(facts)

	got := strings.Join(facts, "\n")

	}

	var facts []string
	for id, obj := range defs {
		if obj != nil {
			fact := fmt.Sprintf("L%d defs %s", id.Pos().Line(), obj)
			facts = append(facts, fact)
		}
	}
	for id, obj := range uses {
		fact := fmt.Sprintf("L%d uses %s", id.Pos().Line(), obj)
		facts = append(facts, fact)
	}
	sort.Strings(facts)

	got := strings.Join(facts, "\n")
	if got != want {

//     / | \
// .. 1  2  3 ..   constant
//     \ | /
//     Bottom      not constant
//
// It starts with optimistically assuming that all SSA values are initially Top
// and then propagates constant facts only along reachable control flow paths.
// Since some basic blocks are not visited yet, corresponding inputs of phi become
// Top, we use the meet(phi) to compute its lattice.
//
// 	  Top ∩ any = any