teamai-test/.teamai/skills/common/golang-troubleshooting/references/code-review-flags.md

Code Review Red Flags

If you see these in code review, flag them:

Pattern	Why It's Bad
result, _ := doSomething()	Silent error — mystery bugs later
go func() { }() without context	Can't cancel, leaks goroutine
Channel without close	Goroutine leak when sender exits
time.After in hot loop	Repeated timer allocation/churn; use a reusable timer when reset semantics matter
Global map without mutex	Data race
defer inside hot loop	Deferred calls pile up until return
json.Marshal in hot path	Expensive, causes GC pressure
for range without ok check	Misses channel close
var err *MyError; return err	Interface nil gotcha
http.Get without timeout	Default client has no timeout
fmt.Errorf("...: %v", err)	Use %w to preserve error chain
:= shadowing outer err	Inner err is a new variable, outer stays nil
func (c Counter) Lock()	Value receiver copies sync types
wg.Add(1) inside goroutine	Race: Wait() may return before Add()
http.Error(...) without return	Handler keeps executing after error
iota starting at 0 for enums	Zero value ambiguous with first constant
strings.Trim(s, "prefix")	Strips char set, not substring
log.Fatal(err) in func w/ defer	os.Exit skips all deferred cleanup
t1 == t2 for time.Time	Use .Equal() — monotonic clock differs
rows, _ := db.Query(...) no Close	Leaks database connections
ch <- val after close(ch)	Panics — only sender should close
select { default: } in loop	Busy loop — burns CPU without blocking
int32(bigInt64)	Silent truncation — no overflow check
filepath.Join(base, userInput)	Doesn't prevent ../ path traversal
regexp.MustCompile in handler	Recompiles every call — move to package var
fallthrough in switch	Executes next case unconditionally