// run

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test that heavy recursion works. Simple torture test for
// segmented stacks: do math in unary by recursion.

package main

import "runtime"

type Number *Number

// -------------------------------------
// Peano primitives

func zero() *Number {
	return nil

# Check that we don't get infinite recursion when loading a package with
# an import cycle and another error. Verifies #25830.
! go list
stderr 'found packages a \(a.go\) and b \(b.go\)'

-- go.mod --
module errcycle

go 1.16
-- a.go --
package a

import _ "errcycle"
-- b.go --

	// (from text_32), and saTmp will typically be much larger, so we'll use saTmp.
	// When deeper recursions come back to recurse_32, now oldTmp is
	// the saTmp from the top-most recursion, it is typically larger than
	// the current saTmp (because the current sa gets smaller and smaller
	// as the recursion gets deeper), and we keep reusing that top-most
	// large saTmp instead of the offered smaller ones.
	//

	ok = m.match(typ, true)
	return m.reason, ok
}

// argMatcher recursively matches types against the printfArgType t.
//
// To short-circuit recursion, it keeps track of types that have already been
// matched (or are in the process of being matched) via the seen map. Recursion
// arises from the compound types {map,chan,slice} which may be printed with %d
// etc. if that is appropriate for their element types, as well as from type

// Note 2. About jn(n,x), yn(n,x)
//      For n=0, j0(x) is called,
//      for n=1, j1(x) is called,
//      for n<x, forward recursion is used starting
//      from values of j0(x) and j1(x).
//      for n>x, a continued fraction approximation to
//      j(n,x)/j(n-1,x) is evaluated and then backward
//      recursion is used starting from a supposed value
//      for j(n,x). The resulting value of j(0,x) is

TEXT ·chain1(SB),NOSPLIT,$48-0 // Doesn't go over
	RET
TEXT ·chain2(SB),NOSPLIT,$64-0
	CALL ·chainEnd(SB)
	RET
TEXT ·chainEnd(SB),NOSPLIT,$1000-0 // Should be reported twice
	RET

// Test reporting of rootless recursion
TEXT ·startRec(SB),NOSPLIT|NOFRAME,$0-0
	CALL ·startRec0(SB)
	RET
TEXT ·startRec0(SB),NOSPLIT|NOFRAME,$0-0
	CALL ·startRec(SB)

import (
	"bytes"
	"fmt"
	"sort"
	"strings"
)

const (
	// Upper limit for recursion depth. Used to catch infinite recursions
	// due to implementation issues (e.g., see issues go.dev/issue/48619, go.dev/issue/48656).
	unificationDepthLimit = 50

	// Whether to panic when unificationDepthLimit is reached.
	// If disabled, a recursion depth overflow results in a (quiet)
	// unification failure.
	panicAtUnificationDepthLimit = true

Checks: >
        # LINT.IfChange(checks)
        -*,clang-diagnostic-*,llvm-*,misc-*,
        -misc-unused-parameters,
        -misc-non-private-member-variables-in-classes,
        -misc-no-recursion,
        bugprone-argument-comment,
        bugprone-assert-side-effect,
        bugprone-branch-clone,
        bugprone-copy-constructor-init,
        bugprone-dangling-handle,
        bugprone-dynamic-static-initializers,

// verifyInterfaceMethodRecvs verifies that method receiver types
// are named if the methods belong to a named interface type.
func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
	// avoid endless recursion in case of an embedding bug that lead to a cycle
	if level > 10 {
		t.Errorf("%s: embeds itself", named)
		return
	}

	iface, _ := named.Underlying().(*types.Interface)
	if iface == nil {

import (
	"bytes"
	"fmt"
	"sort"
	"strings"
)

const (
	// Upper limit for recursion depth. Used to catch infinite recursions
	// due to implementation issues (e.g., see issues go.dev/issue/48619, go.dev/issue/48656).
	unificationDepthLimit = 50

	// Whether to panic when unificationDepthLimit is reached.
	// If disabled, a recursion depth overflow results in a (quiet)
	// unification failure.
	panicAtUnificationDepthLimit = true