gopls/internal/test/marker/testdata/diagnostics/analyzers.txt

Test of warning diagnostics from various analyzers:
copylocks, printf, slog, tests, timeformat, nilness, and cgocall.

-- settings.json --
{
	"pullDiagnostics": true
}

-- go.mod --
module example.com
go 1.23

-- flags --
-min_go_command=go1.23
-cgo

-- bad/bad_test.go --
package bad

import (
	"fmt"
	"iter"
	"log/slog"
	"sync"
	"testing"
	"time"
)

// copylocks
func _() {
	var x sync.Mutex
	_ = x //@diag("x", re"assignment copies lock value to _: sync.Mutex")
}

// printf
func _() {
	printfWrapper("%s") //@diag(re`%s`, re"example.com/bad.printfWrapper format %s reads arg #1, but call has 0 args")
}

func printfWrapper(format string, args ...any) {
	fmt.Printf(format, args...)
}

// tests
func Testbad(t *testing.T) { //@diag("Testbad", re"Testbad has malformed name: first letter after 'Test' must not be lowercase")
}

// timeformat
func _() {
	now := time.Now()
	fmt.Println(now.Format("2006-02-01")) //@diag("2006-02-01", re"2006-02-01 should be 2006-01-02")
}

// nilness
func _(ptr *int) {
	if ptr == nil {
		_ = *ptr //@diag("*ptr", re"nil dereference in load")
	}
}

// unusedwrite
func _(s struct{x int}) {
	s.x = 1  //@diag("x", re"unused write to field x")
}

// slog
func _() {
	slog.Info("msg", 1) //@diag("1", re`slog.Info arg "1" should be a string or a slog.Attr`)
}

// waitgroup
func _() {
	var wg sync.WaitGroup
	go func() {
		wg.Add(1) //@diag("(", re"WaitGroup.Add called from inside new goroutine")
	}()
}

// inline
func _() {
	f()  //@diag("f", re"Call of bad.f should be inlined")
}

//go:fix inline
func f() { fmt.Println(1) }

// recursiveiter
func F() iter.Seq[int] {
	return func(yield func(int) bool) {
		for range F() {} //@ diag("range", re"inefficient recursion in iterator F")
	}
}

-- cgocall/cgocall.go --
package cgocall

// Note: this test must be in a separate package, as the unsafe import
// silences the unusedwrite analyzer.
import "unsafe"

// void f(void *ptr) {}
import "C"

// cgocall
func _(c chan bool) {
	C.f(unsafe.Pointer(&c)) //@ diag("unsafe", re"passing Go type with embedded pointer to C")
}

-- maprange/maprange.go --
package maprange

import "maps"

func _(m map[int]int) {
	for range maps.Keys(m) {} //@ diag("maps.Keys", re"unnecessary and inefficient call of maps.Keys")
}

-- unusedresult/unusedresult.go --
package unusedresult

import "fmt"

func _() {
	fmt.Appendf(nil, "%d", 1) //@ diag("fmt.Appendf", re"result.*not used")
}

-- staticcheck/staticcheck.go --
package staticcheck

// staticcheck includes hundreds of other analyzers.
// Here we test only two: one enabled by default, one disabled.

func S1000(ch chan int) {
	select { case <-ch: } //@ diag("select", re"use .*receive instead of select")
}

func S1011(x, y []int) {
	for _, e := range y {
		x = append(x, e) // no "replace loop with append" diagnostic
	}
}

-- sqlrowserr/sqlrowserr.go --
package sqlrowserr

import "database/sql"

func _(db *sql.DB) {
	rows, err := db.Query("") //@ diag("db.Query", re`sql.Rows "rows" is used in Next loop at line .. without final check of rows.Err\(\)`)
	if err != nil {
		return
	}
	defer rows.Close() // ignore error
	for rows.Next() {
		rows.Scan() // ignore error
	}
}