pkg go/constant, const Bool Kind
pkg go/constant, const Complex = 5
pkg go/constant, const Complex Kind
pkg go/constant, const Float = 4
pkg go/constant, const Float Kind
pkg go/constant, const Int = 3
pkg go/constant, const Int Kind
pkg go/constant, const String = 2
pkg go/constant, const String Kind
pkg go/constant, const Unknown = 0
pkg go/constant, const Unknown Kind

pkg go/ast, type IndexListExpr struct, Rbrack token.Pos
pkg go/ast, type IndexListExpr struct, X Expr
pkg go/ast, type TypeSpec struct, TypeParams *FieldList
pkg go/constant, method (Kind) String() string
pkg go/token, const TILDE = 88
pkg go/token, const TILDE Token
pkg go/types, func Instantiate(*Context, Type, []Type, bool) (Type, error)
pkg go/types, func NewContext() *Context

then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.
These kinds of changes are unavoidable and
[permitted by the Go 1 compatibility rules](/doc/go1compat).
Even so, Go provides a mechanism called GODEBUG to
reduce the impact such changes have on Go developers

pkg log/slog, const KindAny Kind #56345
pkg log/slog, const KindBool = 1 #56345
pkg log/slog, const KindBool Kind #56345
pkg log/slog, const KindDuration = 2 #56345
pkg log/slog, const KindDuration Kind #56345
pkg log/slog, const KindFloat64 = 3 #56345
pkg log/slog, const KindFloat64 Kind #56345
pkg log/slog, const KindGroup = 8 #56345
pkg log/slog, const KindGroup Kind #56345
pkg log/slog, const KindInt64 = 4 #56345

pkg regexp/syntax, const ErrNestingDepth = "expression nests too deeply" #51684
pkg regexp/syntax, const ErrNestingDepth ErrorCode #51684
pkg runtime/debug, func SetMemoryLimit(int64) int64 #48409
pkg sort, func Find(int, func(int) int) (int, bool) #50340
pkg sync/atomic, method (*Bool) CompareAndSwap(bool, bool) bool #50860
pkg sync/atomic, method (*Bool) Load() bool #50860
pkg sync/atomic, method (*Bool) Store(bool) #50860