gotools/gopls/internal/golang/completion/printf.go

// printfArgKind returns the expected objKind when completing a
// printf-like operand. call is the printf-like function call, and
// argIdx is the index of call.Args being completed.
func printfArgKind(info *types.Info, call *ast.CallExpr, argIdx int) objKind { … }

// formatOperandKind returns the objKind corresponding to format's
// operandIdx'th operand.
func formatOperandKind(format string, operandIdx int) objKind { … }

type formatOperand …

// parsePrintfVerb parses the leading printf verb in f. The opening
// "%" must already be trimmed from f. prevIdx is the previous
// operand's index, or zero if this is the first verb. The format
// string is returned with the leading verb removed. Multiple operands
// can be returned in the case of dynamic widths such as "%*.*f".
func parsePrintfVerb(f string, prevIdx int) (string, []formatOperand) { … }