printf

Overview ¶

Package printf defines an Analyzer that checks consistency of Printf format strings and arguments.

Analyzer printf ¶

printf: check consistency of Printf format strings and arguments

The check applies to calls of the formatting functions such as fmt.Printf and fmt.Sprintf, as well as any detected wrappers of those functions.

In this example, the %d format operator requires an integer operand:

fmt.Printf("%d", "hello") // fmt.Printf format %d has arg "hello" of wrong type string

See the documentation of the fmt package for the complete set of format operators and their operand types.

To enable printf checking on a function that is not found by this analyzer's heuristics (for example, because control is obscured by dynamic method calls), insert a bogus call:

func MyPrintf(format string, args ...any) {
	if false {
		_ = fmt.Sprintf(format, args...) // enable printf checker
	}
	...
}

The -funcs flag specifies a comma-separated list of names of additional known formatting functions or methods. If the name contains a period, it must denote a specific function using one of the following forms:

dir/pkg.Function
dir/pkg.Type.Method
(*dir/pkg.Type).Method

Otherwise the name is interpreted as a case-insensitive unqualified identifier such as "errorf". Either way, if a listed name ends in f, the function is assumed to be Printf-like, taking a format string before the argument list. Otherwise it is assumed to be Print-like, taking a list of arguments with no format string.